Fatima Mohammed Munwar Khalifa.pdf

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بسم اهلل الرمحن الرحيم

Assessment of Chemical, Physical Properties and Antibiotic

Residues in Fresh Cow Milk, Gezira State, Sudan

Fatima Mohammed Munwar Khalifa

B.Sc. Honors in Agricultural (Animal Production)

Alneelain University (2013)

A Dissertation

Submitted to the University of Gezira in Partial Fulfillment of the

Requirements for the Award of the Degree of Master of Science

Animal Production (Dairy Production)

Department of Animal Science

Faculty of Agricultural Sciences

Auguts, 2018

Supervision Committee

Name Position Signature

Prof. Hyder Osman Abdalla Osman Main Supervisor ……………….

Prof. Greeb Alla Hassan Elobeid Co. supervisor ……………….

Date: August, 2018

Examination Committee:

Name Position Signature

Prof. Hyder Osman Abdalla Osman Chair Person ……………………

Dr. Mahassin Abd Elrazig Mohammed External Examiner ……………………

Dr. Fawgia Sir Elkhatim Siddig Internal Examiner ……………………

Date of Examination: 02/08/2018

DEDICATION`

To the Middle of the Contract

Father and Mother

To the Three Pearl Beads

My brothers

To whom I am Old to Be

And to all of my Friends

ACKNOWLEDGEMENT

All praise being to Allah, the almighty for his uncounted support and for giving

me health, patience, power and helping me to accomplish this work.

I would like to show my deep gratitude and sincere appreciation to my

supervisorProf. Hyder Osman Abd Allah to whom I feel quite indebted for his

close and kind supervision, continuous follow up, cooperation and his valuable

guidance, advices, comment. and his continuous support in every part of this

study.

A lot of my thank and gratitude are extended to Prof. Greeballa Hassan Elobeid

my co-supervisor for his endless help given throughout this work,keen interests,

guidance from conception to conclusion of this work.

I am profoundly grateful to the working group of the Kafi Dairy Collection Center

Mr. Musaab Mohamed, Motwakel Ahmed Mohammed, Hamza Ahmed Ismail and

Mohamed Abdalla Yousif. My thanks and appreciation extended to the working

Group of Al Rahma Dairy Products Factory, for analyzing the samples.

I sincerely appreciate the efforts of Dr. Siddig Eisa Idris who helped in statistical

data analysis. Lastly, great thanks go to my M.Sc. classmates of academic for their

encouragement.

Assessment of Chemical, Physical Properties and Antibiotic Residues in Fresh Cow Milk,

Gezira State, Sudan

ABSTRACT

Milk is an essential food for humans, nevertheless it may be subjected to a lot of adulteration and

contamination that affect its quality. The objective of the study was to assess the chemical and

physical properties, antibiotic residues and milk handling practices in Wad Medani area. The

physical properties of milk were determined by using Milkana® Express Plus apparatus which is

a sort of milk analyzer. Moreover antibiotic detection was performed using TwinSensor

incubator. A total of 135 milk samples were collected from different sources ( 45 from dairy

farms, 45 from Kafi dairy collection center and 45 from groceries). The samples were subjected

to chemical analysis (fat, protein, SNF, and lactose) and physical analysis (density, added water,

freezing point and presence of antibiotic residues). On the other hand a survey was conducted to

collect information about production conditions, and milk handling practices. A total of 50

participants from milk vendors, milk retailers, smallholder dairy farmers, onecollection center and

20 groceries were interviewed. The survey includes: barn type, cleaning practices, hygienic

conditions of the cow and theirmillers, source of water, milking containers, milk quality test and

marketing system. The chemical and physical analysis showed no significant differences (P>0.05)

in fat % and density among the different sources, while there was a significant difference

(P≤0.01) in protein, SNF, lactose content, freezing point and added water. The fat, protein, SNF,

and lactose content were higher in the groceries milk samples (3.82%, 3.22%, 8.38% and 4.45%)

respectively, while they were lower in Kafi collection center samples (3.03%, 2.8%, 7.8% and

4.08%) respectively. No antibiotic residues were detected in farms milk samples, while there was

15% of the collection center samples had detectable antibiotic residues and only 4.4% of the

groceries samples had detectable antibiotic residues. The survey indicated that all farms

practicing hand milking and none of them used to cool milk prior to marketing, no milking barns

were available in all farms. 45% of the farms use aluminum milk containers, 18% use plastic milk

containers, the main source of water was artesian wells. Therefore, it is recommended that more

strict rules and severe penalties should be applied against the use of antibiotic residues and the

use of plastic milk containers. For longer and good preservation, milk should be cooled before

marketing.

الطازج بقارألا لبن في الحيوية المضادات وبقايا والفيزيائية الكيميائية الخصائص تقييم السودان ،الجزيرة والية

خليفة منور محمد فاطمة

ملخص الدراسة

. جودته علي يؤثر قد الذي والتلوث الغش من للكثير يتعرض قد ذلك ومع, لإلنسان ضروري غذاء اللبن علي والتعرف الحيوية المضادات وبقايا والفيزيائية الكيمائية الخصائص تقييم هو الدراسة هذه من الهدف ®Milkaجهاز باستخدام للحليب الفيزيائية الخواص تحديد تم. مدني ود منطقة في الحليب مع التعامل طرق

Express Plus باستخدام الحيوية المضادات عن الكشف تم بينما. للحليب محلل جهاز عن عبارة وهو من عينة 45) مختلفة مصادر من الحليب من عينة 135 جمع تم. Twin Siensor incubatorجهاز الكيميائي للتحليل العينات أخضعت(. البقاالت من 45و األلبان لتجميع كافي مركز من 45 ،األلبان مزارع

التجمد نقطة المضاف، الماء الكثافة،) الفيزيائي والتحليل( الالكتوز الصلبة، الكلية المواد البروتين، الدهن،) وكيفية ،اإلنتاج ظروف حول معلومات لجمع مسح إجراء تم ،أخري ناحية من(. الحيوية المضادات وبقايا

تجميع ومركز المزارع وأصحاب الحليب، باعة من مشاركا 50 مع مقابالت أجريت. الحليب مع التعامل مصدر وحليبها، لألبقار الصحية الحالة التنظيف، طرق الحظيرة، نوع: علي المسح اشتمل. بقالة 20و واحد

وجود عدم والفيزيائي الكيميائي التحليل اظهر. التسويق ونظام الحليب، جودة اختبار الحلب، أواني الماء، فرق وجد حين في. المختلفة المصادر في اللبن وكثافة الدهون نسبة في (P>0.05)معنوي فرق

والماء التجمد نقطة الالكتوز، محتوي الدهنية، غير الصلبة المواد البروتين، في (P≤0.01)معنوي لبن عينات في اعلي الالكتوز ومحتوي الدهنية، غير الصلبة والمواد والبروتين الدهن نسبة كانت. المضاف كافي تجميع مركز في اقل كانت بينما التوالي، علي( %4.45 ,%3.38 ,%3.22 ,%3.82) البقاالت

في الحيوية للمضادات بقايا أي علي العثور يتم لم. التوالي علي( 4.08% ,7.8% ,2.8% ,3.03%) وفي التجميع مركز عينات من %15في حيوية مضادات بقايا علي عثر بينما المزارع من اللبن عينات نظام يستخدم لم كما اليدوي الحليب تمارس المزارع جميع نأ ليإ المسح أشار. البقاالت عينات من 4.4% %45نأ ليإ المسح أشار. المزارع جميع في للحليب غرفه توجد لم كما التسويق، قبل منها أي في التبريد

الرئيسي المصدر نأ وجد. بالستيكية وانيأ تستخدم منها %18 بينما المونيوم، وانيأ تستخدم المزارع من استعمال ضد المشددة والعقوبات اللوائح بتطبيق الدراسة توصي. االرتوازية اآلبار هو المزارع في للمياه

قبل الحليب تبريد يجب ،أطول لمدة الجيد للحفظ. البالستيكية األواني استعمال وضد الحيوية، المضادات .التسويق

LIST OF CONTENTS Page

Dedication ………………………………………………………………………...…. iv

Acknowledgement …………………………………………………………………... v

Abstract ……………………………………………………………………………… vi

Arabic Abstract ……………………………………………………………………… vii

Table of Contents ……………………………………………………………………. viii

List of Tables ………………………………………………………………………... x

List of Abbreviations and Acronyms………………………………………………... xi

CHAPTER ONE: ………………………..………………………………………..……... 1

1. INTRODUCTION………………..……………………………………………….…. 1

CHAPTER TWO…………………………..………………………………………..…… 4 2. LITERATURE REVIEW…………………………………………………………... 4 2.1. Milk production systems in Sudan……………………………………………….. 4

2.1.1. Intensive production system……………………………………………... 5

2.1.2. The specialized private dairy farms……………………………………... 5

2.1.3. The production of milk in irrigated schemes……………………………. 6

2.1.4. Public sector dairy farms………………………………………………… 6

2.1.5. Traditional forms of dairy farms………………………………………… 7

2.2. Milk composition………………………………………………………………… 7

Milk adulteration………………………………………………………………….

Butter fat content…………………………………………………………………

2.5. Antibiotics and antibiotics residues in milk……………………………………… 9

2.6. Quality control of raw milk……………………………………………………… 10

2.6.1. Assessment of milk quality……………………………………………… 12

2.6.1.1. Alcohol test ………………………………………………….. 12

2.6.1.2. Boiling test…………………………………………………… 12

2.6.1.3. Lactometer test ………………………………………………. 13

2.6.1.4. Laboratory tests ……………………………………………… 13

2.6.1.5. Determination of freezing point……………………………… 13

2.7. Physical properties of milk………………………………………………………. 14

2.7.1. Milk color……………………………………………………………….. 14

2.7.2. Smell of milk ……………………………………………………………. 14

2.7.3. Specific gravity………………………………………………………….. 15

2.7.4. Foreign bodies in milk…………………………………………………... 16

2.7.5. Milk pH………………………………………………………………….. 16

2.7.6. Milk clotting…………………………………………………………….. 17

2.8. Milk spoilage…………………………………………………………………….. 18

2.8.1. Causes of milk spoilage…………………………………………………. 19

2.8.1.1. Environmental factors……………………………………….. 19

2.8.1.2. Milk handling personnel……………………………………... 20

2.8.1.3. Milk handling equipment……………………………………. 20

2.8.1.4. Animal factors……………………………………………….. 21

2.8.1.5. Milking practices…………………………………………….. 21

2.8.2. Control of milk spoilage…………………………………………………. 22

CHAPTAR THREE……………………………………………………………………… 24

3. MATERIAL AND METHODS………………………………………………….… 24

3.1 Study area……………………………………………………………………….. 24

3.2. Study design……………………………………………………………………… 24

3.3. Target population………………………………………………………………… 24

3.4. Assessment of dairy management practices……………………………………... 24

3.4.1. Farm hygiene…………………………………………………………….. 24

3.5. Sources of milk and sampling……………………………………………………. 25

3.6. Laboratory analysis of milk samples…………………………………………….. 25

3.6.1. Physical analysis of milk samples………………………………………. 25

3.6.1.1. The procedure………………………………………………… 25

3.6.2. Detection of antibiotic residues in milk…………………………………. 25

3.6.2.1. The procedure…………………………………………………. 26

3.7. Data analysis…………………………………………………………………….. 26

CHAPTER FOUR………………………………………………………………............... 27

4. RESULT AND DISCUSION……………...……………………………………….. 27

4.1. Chemical properties of raw milk samples collected from dairy farms, Kafi dairy

collection center and groceries…………………………………………………...

4.2. Physical properties of raw milk collected from different sources……………….. 28

4.3. Antibiotic residues in the milk samples collected from different sources……….. 29

4.4. Demographic characteristics of the study smallholder…………………………... 30

4.4.1. Dairy cattle breed………………………………………………………... 31

4.4.2. The cow milk handling practices by producers………………………….. 32

4.4.3. Type of housing and hygienic practices…………………………………. 33

4.4.4. Hygienic practices……………………………………………………….. 35

4.4.5. Raw milk marketing system ……………………………………………. 36

4.4.6. Milk quality test in a collection center …………………………………. 38

CHAPTER FIVE…………………………………………………………………………. 41

5. CONCLUSIONS AND RECOMMENDATIONS …………………………… 41

5.1. Conclusions……………………….……………………………………… 41

5.2 Recommendations……………………...………………………………... 41

REFERENCES ………………………………………………………………….……… 42

APPENDIX ……..……………………………………………………………….……… 52

LIST OF TABLE

Table Page 1. Chemical composition of raw milk samples from different sources…………. 28

2. Physiochemical properties of raw milk collected from different sources……. 29

3. Antibiotic residues in raw milk samples obtained from different sources…… 30

4. Gender, location and educational level of respondents in the study area……. 31

5. Breeds, milk yield and productive cows in the dairy farms ………………….. 32

6. General practices and milking process in some dairy farms………………… 33

7. Types of housing and barn cleaning frequency………………………………. 34

8. General hygiene and milking practices and water supply…………………… 37

9. Milk handling at the groceries……………………………………………….. 39

10. Milk quality tests……………………………………………………………. 40

LIST OF ABBREVIATIONS AND ACRONYMS

MAAPA: Ministry of Agriculture, Animal Production Administration

SNF: Sold Not Fat

TS: Total Solid

FDA: Food and Drug Administration

SSMO: Sudanese Standers and Metrology Organization

SCC: Somatic Cell Count

pH: Hydrogen Potential

CHAPTER ONE

INTRODUCTION

Milk is considered the most nutritious human food and is consumed in all cultures across

the world(FAO, 1986, McGee and Harold, 2004). Over 60% of global milk production

is in Europe, followed by the Americas at about 26% and Africa especially the Sub

Saharan countries produce the least (2%) milk (FAO, 1986). The Sudan occupy an area

estimated to be 1.881.000 km with a great variation in climatic conditions and

vegetation. The country is also endowed with diverse agricultural environments which

are determined by climate, animal resources and human population density. Sudan has a

human population of about 33.419.625 million people and more than 80% of the work

force depend on agriculture. According to estimates recorded by the Ministry of Animal

Resources in year 2008, the number of animal population were about 40 millions head

of cattle, 50 millions head of sheep, 43 million head of goats and 4 million head of

camels. More than 90% of the livestock in the country is owned by nomadic and semi-

nomadic tribes, with a regular system of seasonal migration mostly from North to South

and vice versa. Among cattle population in the Sudan there are two important types,

Kenana and Butana which show a considerable milk producing potential, but they are

relatively few in numbers (2.3 and 5 million heads of Butana and Kenana respectively)

as compared to other cattle types in the Sudan (Hamza 2011). Fresh milk produced in

the Sudan is about 7.1 tons. Most of the yield (95%) is produced by nomads and 5% in

urban areas. The producing cross bred cows is about 500,000 head distributed in urban

areas and around the towns and cities of the country and produce 95% of the milk yield

produced in urban areas (FAO, 2006 and Khalid, 2006).Milk and dairy products are

generally very rich in nutrients and thus provide an ideal growth environment for many

microorganisms. These includes spoilage organisms in milk, some strains of which can

survive pasteurization and grow at refrigeration temperatures. In addition, milk can be a

potentially significant source of food-borne pathogens, the presence of which is

determined by the health of the dairy herd, quality of the raw milk, milking and pre-

storage conditions, available storage facilities and technologies, and hygiene of the

animals, environment and workers. Milk and dairy products can also contain chemical

hazards and contaminants – mainly introduced through the environment, animal

feedstuffs, animal husbandry and industry practices (Ellen, 2013). The driving force

behind any adulteration is to maximise revenues by either using a cheap ingredient to

(partially) substitute a more expensive one, or to (partially) remove the valued

components in the hope that the altered product passes undetected by the final user or

consumer. Watering of milk or skimming off cream are good examples to illustrate the

point, and these fraudulent operations have been practised for a long time (Gerrit,

2003).The keeping quality of milk is a function of on-farm hygiene and the milk

handling practices. Milk produced by the farmers often goes bad since husbandry

practices are at household level and milk quality is always compromised. With the

increased cost of production, subsistence dairy farmers face enormous costs

maintaining their low-output cows and the high losses from discarded milk due to

spoilage. Despite the losses, the on-farm factors leading to milk spoilage at production

level have not been studied. This study, therefore, was conducted to identify the major

on- farm factors affecting the milk quality in Wad Madani city.

Objective of the study General objectives:-

To evaluate out the main factors that lead to milk spoilage since the milking of the cow

untill it reached the consumer, and accordingly proposed a directive for the farmers

involve the proper procedure of milk handling.

Specific objectives are to:

1. Visit some farms and study the situation under which they produce the milk.

2. Assess chemical and physical quality properties of the milk since it produced,

untill it reached the consumer .

3. Determine the factors lead to milk spoilage and the proper way of handling milk

to reduce spoilage.

4. Determine the level of antibiotic drugs residues in raw milk and physical quality

of milk from cattle in the study area.

CHAPTER TWO

LITERATURE REVIEW

2.1 Milk production systems in the Sudan

Sudan cattle's belong to the species Bosindicus which include humped cattle (zebu) of

Asia and Africa. Sudanese cattle are broadly classified into two breeds, Nilotic cattle,

and North Sudan zebu cattle. There are six main indigenous zebu cattle among which

Kenana and Butana are known for their high productivity. The milking potential of other

breeds, namely Baggara, Nilotic, Umbararo and Nuba is low. The profitability of a dairy

enterprise is mainly related to obtaining as much milk as possible within the prevalent

nutritional environment, relative to the maintenance cost of the animals. Figures for the

milk yield of cattle under traditional management were not available. Among the cattle

population, Kenana and Butana are promising indigenous milk breeds, which under

improved feeding and management in research stations yield more than 1500 kg milk

per lactation relative to international standard (Saeed et al., 1987, El Habeeb, 1991 and

Musa et al., 2005). Through experience, many herds men have come to understand that

the best results are obtained by crossing the best local cattle (usually Kenana and

Butana) with exotic breeds (usually Friesian) (Musa et al., 2005). This process of fast

upgrading aims at increasing local milk production in response to the rising demand in

urban areas (Hussein, 2008).

In Sudan, urban milk supply largely comes from village herds and its marketing is by

milk venders who distribute raw milk to households as the organized dairy

establishments are limited (Elmagli and El Zubeir, 2006). Milk production system in

Khartoum State, depend largely on the traditional sector, which produces about 80% of

the milk consumed in the state. Other systems include dairy co-operative societies,

private sector farms and modern dairy farms (Babiker, 2007). The environment (season),

location of the farm with regards to marketing points and the availability of means of

transportation are the important factors that influenced milk supply and marketing in

Sudan (Ahmed and El Zubeir 2013).

The classification of different production patterns is based mainly on the size of

producing unit, technologies and practices adopted by animal breeders and the method

of milk marketing and distribution, plus the mode and production relations

(Mubarak1986).Milk production within this sub-system is organized in various forms,

these include small and large-scale, private producers, parastatal, organization and co-

operatives. Generally, there are three broad cattle production sub-systems both in Gezira

and Khartoum states depending on social structures under which the animals are kept;

cultural/ human settlement-habits, animal type/ breed and availability of feed and

support services (FAO, 2002). These sub-systems are:

2.1.1 Intensive production system

Farmers follow modern dairy management practices to raise pure bred or crossbred dairy

animals or high yielding local cattle. The animals are raised under improved

environmental conditions (housing), given the appropriate nutrition and receive the

required veterinary services as and when necessary. This sub-system is confined to

urban centers and big regional towns and production is totally market oriented. The

cattle are kept under-zero grazing and complete dependence on cultivated forage and

concentrates (Mohammed, 1994). Many milk producers grown their own fodder but

some buy or supplement their own fodder supplies by buying from other farmers. Herd

size vary from several cattle to hundred animals in few instances. This system is

estimated to account for 10% of milk production. This sub-system is characterized by

the existence of small-scale production units owned by private producers as well as

large-scale governmental institutions (Hussein, 2008).

Milk production within this subsystem is organized into different forms, which include

private specialized dairy farms, irrigated schemes and state owned dairy farms:

2.1.2 The specialized private dairy farms

These are owned by private producers. Milk production is for market purposes. Farms

are located in the vicinity of urban centers in the Khartoum and Gezira states. Estimates

of the total number of these farms, the number of animals kept in them and the milk

output produced within this sub-system in the different areas of the Sudan are not

available. Recent estimates of the state Ministry of Agriculture, Animal Production

Administration. (MAAPA, 2004) put the total number of cattle in the Khartoum state at

about 234,501 heads, in about 2058 farms. These units include large scale private

modern dairy farms, parastatal or state owned farms e.g. Capo and Kenana Dairy Farms

which possess modern milk processing plants.

2.1.3 The production of milk in irrigated schemes

This subsystem is confined to Gezira, Rahad and Kuku irrigated schemes. Farmers

within this subsystem keep local breeds, and few of them keep crossbred animals. The

animals are fed on cultivated forage, crop residues and concentrates in addition to the

available natural pasture. In Gezira area there is some degree of integration between

crop and cattle husbandry. Here cattle are kept to produce milk for village community,

are allowed to graze on daily basis near the village and do not migrate as long as feed is

available. Feeding management includes grazing on canal banks, fallow and refuses

grazing. In addition crop residues are fed and the surplus is stored for use at times of

feed scarcity. Sometimes green fodders are also fed if included in crop rotation(Hussein,

2008).

2.1.4 Public sector dairy farms

These farms are mainly research station’s farms which are established to improve

characteristics and potentialities of the local cattle breeds and for provision of training

and services, and to act as pilot schemes for the development of the dairy industry in the

country. Local and exotic breeds are kept in these farms under relatively high standards

of management. Milk productivity per cow within this subsystem is higher than

elsewhere. Recently, these farms, due to the lack of regular funding from the

government and nongovernmental research organization ran out of work and/or failed in

the provision of the required services concerning the promotion of dairy industry

countrywide.

2.1.5 Traditional forms of dairy farms

These forms of dairy systems in the urban centers of Khartoum and Gezira states are

characterized by large numbers of small scale farms. The production pattern is based on

relatively small herds of cattle, goats and sheep. This system is characterized by low

level of production, technology and management practices. Producers depend on

purchased food stuff, therefore, their milk production cost is likely to be relatively high.

They either wholesale their milk or retail it directly to the consumer at homes (Mustafa,

1994).

2.2 Milk composition

Normal cow's milk contains approximately 87.4% water and 12.6% total milk solids

(FAO, 1986, Goff, 2010). The solids consists of 3.9% fat, 3.2% protein, 4.6% lactose

and 0.9% others like minerals, vitamins and nitrogen which affect milk quality (FAO,

1986). However milk composition varies slightly but within normal ranges, within the

same and different breeds as it was reported by (Matthewman, 1993) milk

composition(g/kg) was 54,32 and 46 fat, protein and lactose in BosIndicus species.

while it was 44, 38 and 4 in Bos Taurus species for the same component. Milk is often

described as a colloidal suspension, containing emulsified globules of fat, a

heterogeneous family of major and minor proteins, the carbohydrate lactose, minerals,

vitamins and enzymes. While the classes of constituents are similar for milk from most

species, there are considerable inter-species differences, both qualitatively (i.e. the exact

nature of constituents) and quantitatively (i.e. the amount of each constituent per litre).

The composition and properties of fresh cow’s milk shows considerable variability. The

main factors from which such variability arises are: (a) genetic factors (e.g. breed and

individual), (b) stage of lactation, (c) health status of the cow and (d) environmental

factors (e.g. feed, climate or method of milking) (Adnan, 2009). Under normal

circumstances, cow's milk has a known appearance, color, smell and acidity (PH 6.7) for

which it is known, all being a result of normal composition (Marshall, 1992; Bodyfeltet

al, 1984). It is the deviations from the normal ranges for the components in milk that

will lead to changes manifested either in color, taste, appearance or biochemical levels if

and when determined (Marshall, 1992).

2.3 Butter fat content

Butterfat or milk fat is the fatty portion of milk. Milk and cream are often sold according

to the amount of butterfat they contain. Butterfat is a triglyceride (fat) derived from fatty

acids such as myristic, palmitic, and oleic acids (Goff, 2010). Saturated fatty acids;

palmitic acid 31%, myristic acid 12% and stearic acid 11%, pentadecanoic acid and

heptadecanoic acid are trace fatty acids in milk (Goff, 2010). Unsaturated fatty acids are

oleic acid 24%, palmitoleic acid 4%, linoleic acid 3% and linolenic acid 1% (McGee and

Harold, 2004).

Initially milk fat is secreted in the form of a fat globule surrounded by a membrane (Fox,

1995). Each fat globule is composed almost entirely of triacylglycerols and is

surrounded by a membrane consisting of complex lipids such as phospholipids, along

with proteins. These act as emulsifiers which keep the individual globules from

coalescing and protect the contents of these globules from various enzymes in the fluid

portion of the milk (Fox, 1995).

Although 98% of lipids are triacylglycerols, small amounts of diacylglycerols and

monoacylglycerols, free cholesterol and cholesterol esters, free fatty acids, and

phospholipids are also present (Goff, 2010). Unlike protein and carbohydrates, fat

composition in milk varies widely due to genetic, locational, and nutritional factor

difference between different species (Goff, 2010).

Psychrotrophic bacteria can produce large amounts of extracellular hydrolytic enzymes

that deteriorate proteins and lipids of fluid milk products affecting their shelf life

(Marshall, 1992 and Goff, 1989). This is manifested by the presence of a wide variety of

metabolic by-products, causing off-odors and flavors, in addition to visible changes in

color or texture. Pseudomonads can reduce the diacetyl content of buttermilk and sour

cream leading to a “green” or yogurt-like flavor that affects milk quality (Marshall,

1992).

2.4 Milk adulteration

Food is essential for sustenance of life. Adulteration of food can pose serious risk to

human health. Major food adulteration occurs with milk and milk products. Milk in its

natural form has a high food value, since it is comprised of a wide variety of nutrients

which are essential for proper growth and maintenance of the human body

(Bhamare,2016). Adulterants of milk may be defined as addition of any material to the

milk or removal of any constituent of milk. Adulteration in milk is considered to reduce

the quality and to increase the quantity of milk. Adulterants are mainly added to increase

the shelf life of milk (Siuli Das et al, 2016).

Adulteration of milk can cause the deterioration of dairy products, therefore milk quality

requires the necessity and greater emphasis on regulatory aspects with advanced

methods of analysis and monitoring milk production and processing (Fox and

McSweeney, 1995).

Typically, milk is adulterated either for financial gain or due to unhygienic conditions of

processing, storage, transportation, marketing etc. Milk adulteration has been widely

reported in developing countries such as India, Pakistan, Brazil and China etc.

(Bhamare, 2016).

In Khartoum State, milk is distributed through irregular marketing channels such as

venders on donkeys or by cars in addition to collection centers and some consumers buy

milk directly from the farms. These informal channels make milk uncontrollable and

could influence the nutritional value of milk in case of adulteration (Nahlaet al, 2015).

The common adulteration of milk is addition of water, removal of fat, addition of

starch/cereal flour, skim milk powder gelatin, urea, ammonium sulphate and glucose. By

water adulteration of milk constituents are diluted (Fat and SNF). The water adulterated

milk has less lactometer readings and less SNF content. To mask this other compounds

listed above are added so that milk shows required lactometer reading. The water

adulterated milk will be thin and nonviscous. To mask this also the various substances

are added, so that the adulterated (water) milk will have normal consistency(Siuli Das et

al, 2016).

2.5 Antibiotics and antibiotics residues in milk

The economic need for rationalization in the agricultural field has led to the increased

use of pesticides and active compounds for plants and animals. Contamination of milk

with undesirable residues may occur through the animal itself, the environment and also

during further processing. Sources of residues of different types are considered

toxicological problem when present in milk. These include antibiotics, pesticides,

radionuclides, mycotoxins, plant toxins and other chemical agents. Antibiotic residues in

milk are of concern because they may curtail proper lactic acid fermentation in cultured

products, resulting in spoilage and the ingestion of antibiotic-contaminated milk may

cause a reaction in humans already sensitized to the contaminant (Barbuddhe, 2008).

Defined the antibiotics as “ a natural compound produced mainly by microorganisms or

are compounds obtained by chemical or microbiological modification of natural

compounds. defined antibiotic as miracle drugs that are extensively used for the

treatment and prevention of infectious diseases in animals and humans. They concluded

that antibiotics have greatly enhanced humans and animal's life, reduced mortality and

improved quality of production (El-Hassan, 2006).

Mastitis in dairy cattle is the persistent, inflammatory reaction of the udder tissues. This

is a most common disease in dairy cattle. Milk of cows with sub-clinical mastitis enter

into food chain and can be dangerous to humans. Mastitis causes increased conductivity

in milk due to increased sodium and chloride ions, and is a well-known method to detect

mastitis in milk.El-Hassan(2006)have reported that the accuracy of electrical

conductivity detection of sub clinical mastitis is better than all other indirect methods.

Moreover, the adaptability of this measurement is more in both manual and automatic

cow-side mastitis detection systems. Antibiotics are used mainly to treat a variety of

diseases and 80% of dairy herds use antibiotics for treatment of mastitis disease. These

antibiotics in the form of antimicrobial residues are found in abundance in milk.

Sometimes these reagents are also added to increase the shelf life of milk. Common

antimicrobial drugs are sulfonamides, nitrofurans, tetracyclines sulfonamides

antimicrobial residue, beta-lactam antibiotics i.e., penicillin-G, ampicillin, amoxicillin,

cloxacillin, oxacillin, dicloxacillin, cefadroxyl, Presence of tetracycline, aromatic

amines, gentamicin residue after mastitis treatment, neomycin residues, sulfamethazine

residues,chlorampheni residues, aflatoxin M1 contamination etc. organisms but have

limited effects on drug residues.

The USA food and drug administration (FDA) have identified about eighty drug

residues in animal-derived human food. Maximum residue limit has been set for global

standardization. Presence of antimicrobial reagents in milk may cause potential risk to

the consumer. Residues of these drugs in milk poses serious health hazards such as

allergic reactions, increase in the number of antibiotic resistant, interference in intestinal

flora and some of them (such as sulfamethazine residues) may have carcinogenic

properties. It may also cause tissue damage. It interferes in the bacterial fermentation

process which produces important losses in fermented products. Very low amount of

penicillin residue is a potential cause of urticaria. (Siuli Daset al,2016).

In Egypt, El Sherbini and El sayed (1993) used the Delvotest–P test for the presence of

antibiotic residues in 51 raw milk samples they found that 7.8% of the examined

samples were positive. In Sudan, Barakat (1995) used the Delvotest–P test for the

presence of antibiotic residues in 80 milk samples and they found that 8.7% of the

examined samples were positive. Similarly, studied 250 raw milk samples and found

that 18.6 %, 14.1 % and 8.1 % from vendors, groceries and farms respectively, were

positive for antibiotic residues. Also, using Bacillus subtillis seeded in nutrient agar

plates examined a total of 110 milk samples from cows, which had received antibiotic

treatment through intramammary route and milked before the completion of the

withdrawal period. All the samples examined for inhibitory effect revealed that 76.6 of

the samples were positive (El-Hassan, 2006).

2.6 Quality control of raw milk

The best way to manufacture milk with good quality is to start with a good raw material.

Testing raw milk is thus essential to ensure safety and quality. Raw milk is analysed for

the presence of macroscopic abnormalities, addition of water, microbial quality,

presence of milk from mastatic cows, presence of residues, and composition. Microbial

contamination, since pathogens can compromise the safety and spoilage microorganisms

can limit the shelf life (Adnan, 2009). The contamination of raw milk at the farm can be

due to poor udder preparation or milking conditions, insufficient cleaning, failure in

milk cooling systems or the presence of milk from mastitis cows. Another safety issue is

the presence of residual veterinary drugs, plaguicides or mycotoxins. A very important

aspect of raw milk quality is its composition. The dry matter, fat and protein are

determined by farmers and processors for payment. Other milk components can be

analyzed by the industry for processing performance, labeling and improving quality

(Adnan, 2009). Milk Somatic Cell Count is a key component of national and

international regulation for milk quality and an indicator of udder health and of the

prevalence of clinical and subclinical mastitis in dairy herds. Milk quality can have a

significant impact on milk processing efficiency and product quality. Additionally, milk

quality parameters have to be within certain thresholds as outlined in national laws

(Bernaette et al, 2009). Milk quality can also refer to the properties of milk based on one

or a combination of butterfat content, bacterial counts (microbial quality) and physical

appearance of milk relating to color, smell and presence of foreign or dirt particles (Lore

et al, 2006). Milk that is received at collecting centers or processing plants is graded

based on its quality. This grading helps in deciding whether to accept or reject the milk.

Broadly speaking milk quality also refers to the good and bad attributes of a milk sample

(Lore et al, 2006).

Cow milk has been found to possess qualities that vary with the fat content and this is

also related to the plane of nutrition of the milking cows (Barret and Larkin, 1979). Milk

yield, composition and quality is affected by breed, quantity of milk produced, stage of

lactation, milking interval, season of the year, plane of nutrition and disease status of the

cow and or the udder (Athertone et al, 1977). Milk produced at 37°C should be cooled

immediately to a temperature not exceeding 10°C in order to control bacterial growth.

Bacteria in any milk stored at a standard temperature of 4°C for 15 hours do not multiply

appreciably (Harding, 1995). It is possible to store milk for 7 days at 1.5-2ᵒC provided

the initial quality is good. In good practice, milk produced under proper hygienic

conditions can be stored for 2-3 days (Harding, 1995). Where milk is transported to

collecting centers, farmers should milk their animals towards the time of milk collection

and under no circumstances should evening milk be mixed with morning milk in one

can/container (Barret and Larkin, 1979). It is therefore necessary to examine milk as a

way of establishing the different component levels in it and aspects that lead to

assessment of milk quality:

2.6.1 Assessment of milk quality

Milk quality control is an essential component of any milk processing industry whether

small, medium or large scale. Milk being made up of 87% water, makes it prone to

adulteration by unscrupulous middlemen and unfaithful farm workers. The high nutritive

value of milk makes it an ideal medium for the rapid multiplication of bacteria,

particularly under unhygienic storage conditions and at ambient temperatures. A milk

processor will only be assured of the quality of raw milk if certain basic quality tests are

carried out at various stages of the milk value chain (Marshall, 1992). There is no single

test done at the processing plant, which can determine the hygienic quality of milk

(McKenzie, 2009). It is therefore necessary to examine milk as a way of establishing the

different component levels in it and aspects that lead to assessment of milk quality using

various tests as:

2.6.1.1Alcohol test

The alcohol test determines the pH of milk (FAO, 1986). It is based on instability of the

proteins when the levels of acid and/or rennet are increased and acted upon by the

alcohol. Also increased levels of albumen (colostrum milk) and salt concentrates

(mastitis) results in a positive test (Marshall, 1992). The test is quick, simple and more

sensitive test applied on the platform before milk is accepted, weighed, recorded by all

pooling centers, collecting centers or processing plant. It is a test that detects milk which

is highly acidic (pH<5.3) and medium-acidity milk (pH <6.4).

2.6.1.2 Boiling test

Clot on boiling, is a quick and simple test for determining highly acidic milk (pH<5.8)

or abnormal milk (e.g. colostral or mastitis milk) (FAO, 1986). Such milk cannot stand

the heat treatment in milk processing and must therefore be rejected (Marshall, 1992).

The procedure involves boiling a small amount of milk on a spoon or in a test tube or

other suitable container. If there is clotting, coagulation or precipitation, the milk has

failed the test. However, heavily contaminated fresh milk cannot be detected, even when

the acidity is below 0.20-0.26%. Milk that gives positive clot on boiling has generally

acidity above 0.17% and is not suitable for processing (FAO, 1986) .

2.6.1.3 Lactometer test

Lactometer test is for detecting the change in density of milk. Pure milk has a density

(specific gravity) of 1.026 to 1.032 grams per milliliter (ml). It enables the milk

processor to calculate the milk total solids (% TS) and solids not fat (SNF) (Harding,

1995). Addition of water to milk can be a big problem where there are unfaithful farm

workers, milk transporters and greedy milk hawkers. In normal milk SNF should not be

below 8.5%.

2.6.1.4 Laboratory tests

Apart from the platform tests there are a number of laboratory tests that are used to

assess the quality of milk and milk products before and after processing (McKenzie,

2009). The pH test determination is mainly used for detection of mastitis milk which is

over 7.0 and may be determined by rapidly using the indicator strips or disc (FAO,

1986), or a mixture of milk and Phenolphthalein which is titrated with 0.1 N Sodium

hydroxide. Both titratable acidity and pH are used to measure milk acidity. Most

microorganisms have approximately a neutral pH (6-7.5). Milk has a pH of 6.6 which is

ideal for the growth of many microorganisms and this reduces by the development of

acidity (Marshall,1992).

2.6.1.5 Determination of freezing point

Determination of freezing point is regarded as one of the most accurate tests for

detecting adulteration by added water and estimating the amount of water added (Goff,

1989). Addition of milk solids, salts and sugars will lower the freezing point

significantly. In cows with mastitis, the lactose level is depressed and chlorine salts

increase in milk hence lowering the freezing point, while addition of water lowers the

freezing point of milk to below -0.5°C (FAO, 1986). Pure water freezes at 0.0ºC; the

average freezing point for normal raw milk has been accepted to be -0.52ºC. The

freezing point of milk is normally between -0.512ᵒC and -0.550°C (Goff, 1989).

2.7 Physical properties of milk

2.7.1 Milk color

Quality milk has fat globules and smaller casein micelles both of which are just large

enough to reflect light, contribute to the opaque white color of milk . The fat globules

contain some yellow-orange carotene, enough in some breeds (such as Guernsey and

Jersey cattle) to impart a golden or "creamy" hue to a glass of milk (McGee and Harold,

2004). The riboflavin in the whey portion of milk has a greenish color, which sometimes

can be discerned in skimmed milk or whey products (Marshall, 1992).

2.7.2 Flavour of milk

Good quality milk should have a pleasantly sweet and clean flavor with no distinct

aftertaste (Bodyfelt et al., 1984). Because of the perishability of milk and the nature of

milk production and handling procedures, the development of off-flavors/odors is not

uncommon. To prevent flavor/odor defects in milk, proper milk handling procedures

from the farm to the consumer are essential (Bodyfelt et al, 1984). These defects of milk

smell may be classified according to; absorbed/transmitted, bacterial/microbial and

chemical/enzymatic processes (Marshall, 1992). Absorbed flavors are characterized as

feedy, barny, cowy, weedy, unclean, lacks freshness, stale and refrigerator/cooler odors.

Raw or pasteurized milk products can absorb flavors during production, storage and

distribution. On the farm, off-flavors can be absorbed, or more correctly transmitted,

through the bloodstream of the cow from the lungs and/or rumen into the milk in the

udder (e.g., onion/garlic, feedy, barny and cowy) (Bodyfelt, 1988).

Bacterial activity on milk can cause the smell to be acid, bitter, malty, lacks freshness,

unclean, fruity/fermented, putrid and rancid (Bodyfelt et al, 1984). Bacterial and other

microbial (i.e., yeast or molds) off-flavors result from the growth of microorganisms that

are present in milk due to poor sanitation and/or milk handling practices (Marshall,

1992). Bacteria that are able to grow at refrigeration temperatures (≤45°F/7.2°C), or

psychrotrophic bacteria, are most often responsible for spoiling refrigerated milks (Goff,

1989).

Chemical processes on milk cause cowy (ketosis), salty, rancid, bitter, oxidized,

medicinal, flat and cooked milk flavors. Chemical and enzymatic defects can occur in

both raw and pasteurized milk. The cows may be suffering from ketosis (rare) or

mastitis, which can affect milk flavor (Bodyfelt, 1988). Abusive handling of raw milk

may result in a rancid flavor from the action ofthe naturally occurring lipase enzyme,

which breaks down butterfat to free fatty acids (i.e., butyric acid is perceived as

“rancid”). Chemical or foreign off-flavors can also occur due to contamination with

cleaning chemicals, sanitizers, medicines, or other substances during production or

processing (Bodyfeltet al, 1984).

2.7.3 Specific gravity

Pure milk has a density (specific gravity) of 1.026 to 1.032 grams per ml and this can be

detected by a lactometer . It enables the milk processor to calculate the milk total solids

(% TS) and solids not fat (SNF) (Harding, 1995). Addition of water to milk can be a big

problem where there are unfaithful farm workers, milk transporters and milk hawkers.

According to SSMO (2016) normal milk SNF should not be below 8.5%. Any buyer of

milk should therefore assure himself/herself that the milk he/she purchases is

wholesome and has not been adulterated.

The lactometer test was designed to detect the change in density of such adulterated

milk. Samples of milk from individual cows often have lactometer reading outside the

range of pooled milk, while samples of milk from herds should have readings near the

pooled milk reading, but wrong feeding, may result in low readings (Harding, 1995).

2.7.4 Foreign bodies in milk

Foreign bodies access milk from many sources like the environment, handling

equipment, farm personnel and cow's body (Mbabazi, 2005). Dairy farmers in Sudan do

not have well-constructed and maintained milking parlors, the practice in most parts of

the country is milking in open places. In poorly constructed milking shades, wind blows

with dust particles, pieces of straw and feed materials that may land in milk as foreign

particles (Kurwijila, 1989). Defecation and urination of cows at the time of milking may

introduce foreign matter in good quality milk predisposing it to deterioration (Kurwijila,

1989). In addition, dirty milking places tend to breed flies which may fall in the milk as

foreign materials causing contamination and spoilage (Mbabazi, 2005). Soil serves as

primary source of foreign matter in milk introducing microorganisms and spores in

resting stages which receive nutrients for growth and multiply to increase in numbers to

cause milk spoilage (Mbabazi, 2005). The cow's body is a potential source of foreign

particles that cause milk contamination leading to spoilage (Barret and Larkin, 1979).

Sometimes the teats are smeared with cow dung after milking as a means of preventing

calves from suckling the dam while grazing (Bekele, 1989). On the next milking, the

cow is given its calf to suckle and milking follows without cleaning the teats which

introduces dung particles into the milk.

2.7.5 Milk pH

Milk has a pH of around 6.5 to 6.7, which makes it slightly acidic. Some sources cite

milk as being neutral since it is so close to the neutral pH of 7.0. Milk contains lactic

acid, which is a hydrogen donor or proton donor (Fox, 1995). In its purest form, cow

milk is slightly acidic with a pH of 6.7. Since cow's milk is the mostly consumed milk

type in the world, knowing pH of cow's milk is very important. Homogenized milk is

most acidic while raw milk is medium acidic (Goff, 2010). As milk begins to sour, its

pH levels fall sharply making it even more acidic. Lactobacilli bacteria convert the

sugars in milk into acids, thereby reducing the pH of milk. Completely sour milk has a

pH of about 4.4 (Goff, 2010).

Almost all the milk products have a pH below 7, making them acidic. Buttermilk,

cottage cheese are some of the low acidic milk products. Processed milk products

(cheese and ice-cream) have the highest acid content, hence lowest pH amongst all milk

products (Fox, 1995). Milk coagulates spontaneously at various pH zones, insoluble

casein salts being formed between pH 2.0 and 3.0, isoelectric casein at pH 4.7 and

calcium caseinate at about pH 6.5. At alkaline pH no clotting takes place (Fox, 1995).

2.7.6 Milk clotting

Heavily contaminated fresh milk cannot be detected, even when the acidity is below

0.20-0.26%. Milk that gives positive clot on boiling has generally acidity above 0.17%

and is not suitable for processing (FAO, 1986). Various animals, plants and microbial

proteases have been suggested as milk coagulants (Chwen-Jen Shieha et al., 2009).

However, attention has been focused on the production of milk-clotting enzymes

(MCEs) from microbial sources for use in milk coagulation (Reed and Nagodawithana,

1993). Bacillus subtilisis one of the most investigated microbial organism implicated in

milk clotting because it can produce varieties of clotting substances . It is known to

secrete several proteases during the fermentation of milk products. The capacity of its

strains to produce and secrete large quantities of extracellular enzymes has led it to be

among the most important industrial milk clotting enzyme producers (Reed and

Nagodawithana, 1993). Commercial cheese making utilizes the clotting factors produced

by microorganisms and milk clotting depends also on milk pH and temperature (Chwen-

Jen Shieha et al., 2009).

2.8 Milk spoilage

In order to establish a definition for milk spoilage, the causes of spoilage, milk pH and

microbial activity must be understood. It was discovered that free fatty acids contribute

to the sour taste of spoiled milk and lactic acid buildup contributes the most to the rise of

fatty acid levels in milk (Fromm and Boor, 2004). A lower pH indicates spoilage in milk

due to lactic acid produced by bacteria that break down nutrients and based on this,

spoilage pH is between 3.9 and 4.4 (Ostlie et al., 2003). When raw milk is left standing

for a while, it turns sour as a result of fermentation, where lactic acid bacteria ferment

the lactose in the milk into lactic acid which may render the milk unpleasant to consume

(McGee and Harold, 2004). The lactic acid accumulation denatures proteins and causes

the milk to undergo different transformations in appearance and texture, ranging from an

aggregate to smooth consistency (McGee and Harold, 2004). Therefore milk spoilage is

a term used to describe the deterioration of milk texture, color, odour or flavor to the

point where it is unappetizing or unsuitable for human consumption though it can still be

used in the manufacture of other milk products. Milk from a diseased mammary gland

has almost the same composition as the bovine blood serum. This is in regard to

albumin content increase, has alkaline PH of 6.8-6.9, increased somatic cells (> 500,000

cells/ml), increased chlorides and decreased lactose concentration (FAO, 1986).

Different types of bacteria naturally give different "off tastes" due to changes in milk

fats (FAO, 1986). Milk can absorb off flavors from the environment, which cause

changes in fat molecules. Milk of high quality contains a few hundreds of bacteria per

milliliter whereas bad milk contains millions of bacteria per milliliter (FAO, 1996).

2.8.1 Causes of milk spoilage

The milk secreted into an uninfected cow's udder is sterile. Invariably it becomes

contaminated during milking, cooling and storage, and milk is an excellent medium for

bacteria, yeasts and moulds that are the common contaminants leading to spoilage

(Younan et al., 2007). The common predisposing factors of milk contamination by

microorganisms are the contact surfaces of milking and cooling equipment, milking

personnel, milking cows, the cow's environment and water used on the farm (Mbabazi,

2005). Udder infection has also been implicated in milk contamination but however

aerial contamination of milk by bacteria has been found to be insignificant under normal

production conditions (Younan et al., 2007).

The microbial quality of raw milk is important for the production of dairy products and

it also influences their shelf life (Harding, 1995). Lafarge et al (2004), found that in

fresh milk samples, the dominant bacterial isolate was Lactobacillus lactis, a species of

bacteria used in starter cultures and if left in favorable temperatures leads to spoilage.

2.8.1.1Environmental factors

The common practice in most parts of the country is milking in open places using

buckets, plastic containers or milk gourds (Kurwijila, 1989). In poorly constructed

milking shades, when wind blows, it blows with it dust particles, pieces of straw and

feed materials which may land in milk as foreign particles and lead to milk

contamination (Kurwijila, 1989) report that This was the same situation for the herd

studied by (Ahmed, and El Zubeir, 2013), ideal building material was seldom used in

dairy farms in this only 10% of the studied farms used concrete floor, corrugated iron

roof is used by 6.67% of farms the a traditional housing system constructed from iron

bars, corrugated iron sheets and other local materials such as wood and hay is common.

They added that the houses are partially shaded to accommodate animals and to protect

lactating cows from excessive sun and rain, the building design helps to reduce

environmental stress and provides safe and hygienic conditions to raise the level of

production and to cover the additional cost. The common practice in most parts of the

country is milking in open places using buckets, plastic containers or milk gourds. In

addition, dirty milking places tend to breed flies which may fall in milk causing

contamination and thus spoilage may occur (Mbabazi, 2005). When a cow urinates or

defecates during the milking some of its urine or dung particles may drop into the milk.

Soil and water serve as primary sources of microorganisms contaminating milk. Many

microorganisms exist in resting stages as spores in soil and when they gain access into

milk, they receive nutrients for their growth, multiply and increase in numbers to cause

milk spoilage (Mbabazi, 2005). Using dirty water mainly from wells, to wash milk

utensils and milk adulteration by milk handlers and vendors is a source of

microorganisms especially coliform that lead to milk spoilage (Jay, 1992).

2.8.1.2 Milk handling personnel

Sterile milk from a normal cow's udder becomes contaminated during milking, cooling,

storage and processing (Younan et al., 2007). Milking and handling personnel should be

healthy and acknowledge the importance of cleanliness. Wet milking should be avoided

as organisms present on the milker's hands, cow's teats and udder are washed into the

milking utensil contaminating milk and leading to spoilage. Other sources of

microorganisms are nasal cavities, mouth, dirty hands, skin and the gastrointestinal tract

of both the milker and the animal (Mbabazi, 2005).

2.8.1.3 Milk handling equipment's

Poorly cleaned and sanitized milking utensils may be the source of many

microorganisms which transform high quality milk to an unacceptable product

(Banwart, 1989). The immediate source of thermoduric organisms in milk is milking

utensils used in milk handling. Utensils contain many crevices, cracks and corners that

cannot be easily cleaned, hence pockets that harbor spoilage microorganisms (Mbabazi,

2005; Kurwijila, 1989). The bacterial load of milk increases during transportation and if

the transportation equipment is not appropriate the bacterial counts increase causing

spoilage before milk reaches its destination (Grillet et al., 2007). Although milking

equipment is generally fabricated from stainless steel, which is readily cleaned and

sanitized, some parts made of rubber or other non-metallic materials are difficult to

sanitise, since only moderate use results in the formation of microscopic pores or cracks.

Bacteria attached to these parts are difficult to inactivate by chemical sanitisation. Milk-

handling equipment, utensils and storage tanks are major sources of the gram-negative

psychrotrophic spoilage bacteria.

2.8.1.4 Animal factors

The cow is a potential cause of milk contamination leading to spoilage (Barret and

Larkin, 1979). Sometimes grass contaminants fall from the animal body into the bucket

during milking. Udder infection has also been implicated in milk contamination and

spoilage (Mbabazi, 2005). Most of the spoilage microorganisms are also incriminated in

mastitis, some of which are found on the udder surface (Adams and Moss, 2000). Cows

with mastitis produce poor quality milk with a high bacteria load, mastitis is an

inflammatory disease of the udder caused by a number of microorganisms which include

the coagulase positive Staphylococci, coliforms and streptococci, which dominate the

milk isolates (Goff, 1989). It is believed that mastitis causing organisms gain entry into

the udder via teat orifice and then enters milk (Banwart, 1989). Reports on the

microbiological quality of milk have shown that fecal coliforms, especially E. coli is a

major contaminant of milk leading to spoilage, low shelf-life and poor quality.

High somatic cell count (SCC) raises the suspicion that the raw milk is produced under

poor standards of hygiene and from unhealthy cows; but SCC could increase due to heat

stress in an animal (Nassuna, 2001). Increased SCC is also associated with reduced

suitability of the raw milk for processing into milk products for human consumption.

Milk with high SCC is of poor quality after 14 days of storage, levels of free fatty acids

increased and casein hydrolysis is higher although bacterial load is low.

2.8.1.5 Milking practices

Udder washing before milking should be regarded as a means of removing dirt but not

eliminating bacteria from the cows skin (Barret and Larkin, 1979). According to

Mbabazi (2005), most farmers do not wash the udder of their cows before milking; they

assume allowing the calf to suckle before milking is sufficient to clean the teats.

Sometimes the teats are smeared with cow dung after milking as a means of preventing

calves from suckling the dam while grazing (Bekele, 1989). On the next milking, the

cow is given its calf to suckle and milking follows without cleaning the teats. Saliva

from the calf mouth and unwashed teats increase bacterial counts in the milk causing

spoilage (Kurwijila, 1989). Failure to thoroughly clean and dry the udder and teats is a

common source of coliforms in milk (Barret and Larkin, 1979).

2.8.2 Control of milk spoilage

Milk is a bulky product containing more than 80% water and is difficult to transport. It

has a short storage life and must be consumed immediately unless it is processed to

other products it deteriorates very fast (Matthewman, 1993). Previous researches have

indicated presence of coliforms in milk at farm level but these have been controlled by

chilling temperatures and totally destroyed at pasteurization temperatures (Grillet et al,

2007).

Milk quality across the value chain could be improved through; changing milking

practices to ensure better hygienic conditions, improvement of milk handling and

improvement of storage conditions maintaining the cold chain (Mbabazi, 2005). Milk

should therefore be cooled to 4Cᵒ and transported in insulated trucks for quality delivery

(Mbabazi, 2005). Planners should consider the relative efficiency of alternative milk

marketing systems in terms of costs and marketing margins, product hygiene and quality

range to avoid losses due to spoilage (Mbabazi, 2005).

For production of quality milk a good supply of clean cold water is essential (Younan et

al, 2007). Water used in washing and rinsing milk equipment's and containers for

handling milk must be of the same safety and purity as drinking water (Younan et al,

2007). If water is obtained from an open water supply, care should be taken to prevent

drainage that may contain human feces and other contaminants gaining entry into the

source (Jay, 1992).

Milk should be handled in containers which are made of stainless steel without cracks

where bacteria can lodge and multiply leading to spoilage and these containers should be

unaffected by milk or by chemicals used in cleansing (Younan et al, 2007). Poorly

cleaned and sanitized milking utensils may be the source of many microorganisms

which transform high quality milk to an unacceptable product; therefore thoroughly

cleaned utensils should be used to handle milk (Banwart, 1989).

Milking cows should be kept clean, groomed every day and the udders and teats

thoroughly washed before every milking as the coat and skin are always dirty as this

could act as a source of spoilage bacteria (Barret and Larkin, 1979). Dampening of the

milking parlor floor prior to milking is an effective method of preventing dust from

rising. This floor should be solid, well drained, kept clean and manure should be kept as

far as possible from the milking places as these could be sources of contaminants

causing milk spoilage (Younan et al, 2007).Personnel connected with the milking and

handling of milk should be healthy and should acknowledge the importance of

cleanliness by wearing clean overalls and wash hands with soap and clean water prior to

milking (Mbabazi, 2005). Wet milking should be avoided as organisms present on the

milker's hands, teats and udder of the cow are washed into milking utensil contaminating

the milk and leading to spoilage (Mbabazi, 2005). Before milking, excess water on the

udder should be cleaned with a clean cloth or udder towel and the first draw of milk

should be collected into a strip cup to exclude mastitis milk from mixing with normal

milk as this will limit spoilage (Lore et al, 2006). Milk should be transferred between

containers by pouring and not scooping since this may introduce spoilage bacteria into

the milk and delivery of milk to collecting centers and processing plants shall be within

three hours of milking to avoid deterioration (Lore et al., 2006). Excessive shaking of

milk should be avoided during transportation and this is achieved by minimizing the

head space when filling the containers and these containers should not be kept under

direct sunlight (Lore et al., 2006).

CHAPTER THREE

MATERIALS AND METHODS

3.1Study area

Milk samples used for the study were collected from different sources (Farms, groceries,

and Kafi dairy collection center). The assessment of the milk quality was carried out,

partly, at Alrahama Factory for milk products which is located at 10 km north Wad

Medani center and, partly, at Kafi Dairy Collection Center at Wad Medani City (Central

Market) about 5 km of Wad Medani center. The study was carried out during May to

October 2017.

3.2 Study design

The study was a cross-sectional survey comprising farm inspection or observation,

farmer interviews using structured questionnaires and assessment of physical quality of

raw milk and laboratory analysis.

3.3 Target population

The target population included ten traditional farms, one collection center and twenty

groceries in the study area.

3.4 Assessment of dairy management practices

Smallholder/farms in the target population were visited at milking time either in the

morning or evening between 07:00-8:00 am and 04:00-06:00pm respectively. During the

visits information on farm structures, their physical arrangement, milking and milk

handling practices, and cleanliness of farm premises was obtained by observation of the

farm and a questioner was designed for the farms involved 50 participants. Another

questioner was designed for groceries. Which involved 20 groceries.

3.4.1 Farm hygiene

During the farm visits the level of cleanliness of the milking area, cleanliness of the milk

handling utensils, personnel and cow preparation before milking was observed and

recorded. Also the type of the milking equipment's and cleanliness was checked and

recorded.

3.5 Sources of milk and sampling

The study involved milk samples from randomly selected dairy farms, groceries, and

Kafi dairy collection center. A total of 135 milk samples were collected (45 from dairy

farms, 45 from groceries and 45 from Kafi dairy collected center). The milk was

thoroughly mixed before taking the sample. The samples were collected in (50ml)

plastic containers and then transported in ice box to Alrahama milk Factory and Kafi

Dairy Collection Center for Laboratory analysis.

3.6Laboratory analysis of milk samples

3.6.1 Chemical and Physical analysis of milk samples

The milk chemical constituents (fat, protein, lactose, and SNF) and physical

characteristics (density, freezing point and added water) of the milk samples were

determined by using Milkana® Express Plus apparatus which is a milk analyzer

that analyzing fat, SNF, added water %, freezing point, lactose, conductivity and density

based upon ultra-sound technology in cow and sheep.

3.6.1.1 The procedure

Analyzer absorb 10 ml from milk samples from containers of (50ml) were taken andput

in the sample-holder one at a time with the analyzer in the recess position. Then when

the starting button was activated, the analyzer sucks the milk, makes the measurements,

and returns the milk in the sample-containers and the digital indicator shows the

specified results in a short time (45second).

3.6.2 Detection of antibiotic residues in milk

Antibiotic residues were determined using TwinSensor Milk BT MRL 96 tests -

KIT020,which is a rapid assay in dipstick format detecting the contamination of milk

samples by Betalactams, Tetracycline and Sulfonamides molecules.

3.6.2.1The procedure

Tow hundred µl of milk were added into microwells and mixed and then Incubate for 3

min at 40°C. One dipstick was dipped into each microwell and the incubator was

continued for 3 min at 40°C andread the color intensities.The test requires the use of two

components. The first component is a microwell containing predetermined amounts of

both receptors and antibodies linked to gold particles. The second is a dipstick made up

of a set of membranes with specific capture lines. For a valid test, the red control

line has to be visible after the second incubation. The either two are the specific test

lines placed on both sides of the control line. For example the line for B-lactams is

located below the "control" while the line related to tetracycline is located above it.

When the reagent from the microwell is re-suspended with a milk sample, both receptors

will bind the corresponding analyses if present during the first 3-minutes incubation at

40°C. Afterwards, when the dipstick is dipped into the milk, the liquid starts running

vertically on the dipstick and passes through capture zones.

3.7 Data analysis

Information obtained from the structured questionnaires, farm inspection and laboratory

milk analysis was collaborated during data analysis, questionnaires from respondents by

using SPSS (statistical package for social science, version 20), and laboratory analysis

was performed using (statist F, ver 8), for associations between a risk factor and milk

spoilage.

CHAPTER FOUER

RESULT AND DISCUSSION

4.1 Chemical properties of raw cow milk samples collected from dairy

farms, Kafi dairy collection center and groceries

Chemical composition of raw milk samplescollected from different sources were shown

in (Table1). The mean values of fat content in milk samples collected from the different

sources (farms, groceries, Kafi collection center) showed no significant difference

(P>0.05). Results in this study were lower than that reported by Ahmed (2012) who

reported a fat content of (4.09 and 3.82 %) in milk samples collected from farms in Wad

Medani area and also lower than that reported by Nahla et al. (2015) who reported a fat

content of (5.02±0.60% and 4.72±0.67%) in milk samples collected from Omdurman

and Khartoum North different marketing channels,and lower than that reported by

Lingathurai et al. (2009), but were similar to those of Mohamed and Elzubeir (2007)

who reported a mean fat content of (3.75±1.07 and 3.46±1.17% respectively) in

Omdurman and Khartoum North. The average fat content obtained from dairy farms was

similar to the findings of Francesconi (2006) for milk collected from cooperative

smallholders in Ethiopia. However, Differences infat content may be attributed to

environmental, feeding, management conditions and genetics.

While the Protein content of the same samples showed a highly significant differences

(P≤0.01);the milk samples collected from farms showed the mean values, while the

maximum value was (3.22±0.24) found in groceries sample and the minimum was

(2.8±0.19) found in the collection center sample. Milk is an important source of high

quality protein with a high biological value and digestibility, rich in essential amino-

acids. The protein content of milk from dairy farms was in agreement with that reported

by Enb et al. (2009) and Dehinenet et al. (2013) who obtained a protein content of

(3.20%) and (3.12%), respectively. However, it was lower than that reported by Bellal

and Sima (2013) who reported (3.96%) a value for raw milk samples collected from a

selected dairy plants in Bangladesh.

The mean SNF content of the same samples from different sources showed a significant

difference (P≤0.05),the average SNF content of milk samples obtained from groceries and

farm werehigher than that of milk obtained from collection center.Higher values of SNF

contents were reported by Dehinnet et al. (2013), Bellal and Sima (2013) and Fikrineh et

al. (2012) for raw cow milk samples obtained from dairy farms as compared to the

present study. The variation in SNF content may be due to forage quality, feeding

system, seasonal changes and lactation period (Suman et al., 1998). Lactose content had

a significant difference (P≤0.01) among the different sources, however those values

were higher than that reported by Nahla et al. (2015) and AbdElrahman et al. (2009).

Table 1: Chemical composition of raw milk samples from different sources:

Source

Parameter

Collection

center

Farms Groceries SE SL

Fat% 3.03±0.6 3.51±0.77 3.83±0.95 0.20 N.S

Protein% 2.8ᶜ±0.19 3.06ᵇ±.019 3.22ᵃ±0.24 0.07 **

SNF% 7.8ᶜ±0.9 8.18ᵇ±0.49 8.38ᵃ±0.59 0.2 *

Lactose% 4.08ᶜ±0.23 4.37ᵇ±0.29 4.54ᵃ±0.37 0.09 **

4.2 Physical properties of raw milk collected from different sources

Physiochemical properties of milk collected from different sources were shown in

(Table2). The mean values of milk density in samples from different sources were

(1.028±0.01, 1.024±0.01, and 1.028±0.01 respectively). The values had no significant

difference (P>0.05) among them. These results were similar to Alehegne (2004) who

reported values of specific gravity ranging from 1.025 to 1.029 and Zelalem (2010) who

reported that majority of raw whole milk hadspecific gravity within the range between

1.028 and 1.032. The density of milk was commonly used for quality test mainly to

check for the addition of water to milk or removal of cream. Addition of water to milk

reduces milk density, while removal of cream increases it. There was a highly

significant difference (P≤0.05) in freezing point amongthe different sources of milk

samples collected from different farms, groceries and the collection center, their values

were 0.539±0.05,0.536±0.05 and 0.456±0.05 respectively (Table 2). These values were

higher than that reported by Ghulam and Muhammad(2014) who reported values of

(0.431±0.180C, 0.444±0.2220C and 0.414±0.0180C).The highest mean value of added

water was found in samples collected from the collection center(13.34±3.59%), followed

by milk collected from differentfarms and differentgroceries (7.94±4.26%, 7.83±4.89%

respectively). Values of added water showed a highly significant difference (P≤0.01)

among the different sources. Similar results were reported by Tasci (2011) and Nahla et

al. (2015) who stated that addition of water and ice affected the physical and chemical

quality of milk by altering the proportions of different constituents; addition of water to

milk may also reduces the nutritional and processing quality, palatability and marketing

value of the milk which may lead to condemnation.

Table 2: Physical properties of raw milk collected from different sources:

Source

Parameter

Collection

center

Farms Groceries SE SL

Density% 1.024±0.01 1.028±0.01 1.028±0.01 0.001 N.S

Freezing

point Cᵒ

-0.456ᵇ±0.05 -0.536ᵃ±0.05 -0.539ᵃ±0.05 0.02 *

water%

13.34ᵃ±3.59 7.94ᵇ±4.26 7.83ᵇ±4.89 1.36 **

4.3 Antibiotic residues in the milk samples collected from different

sources

The raw milk samples collected from the different farmsshowed that all milk samples

analyzed were negative for antibiotic test indicating that the milk samples were free

from the detectable concentrations of antibiotic residues; This was an encouraging

finding which suggests that farmers were following the withdrawal periods of different

antibiotics. (Table 3). This result disagreed with EL- Hassan (2006) who found that a

positive results of antibiotic detection in raw milk samples from farms in Khartoum

State. On the other hand (4.4%) and (15%) of the milk samples collected fromgroceries

and collection center respectively had a positive test for antibiotic residues (Table3). The

present results are lower than that of El- Hassan (2006) who found (38.9%) of the milk

samples were positive for antibiotic residues and Barakat (1995) who found that (8.7%)

of the milk samples from Khartoum State were contaminated by antibiotic; this might be

due to the use of antibiotics as preservative method to increase the shelf life of the raw

milk. Similar studies (Karimuribo et al. (2005), Kivaria et al.(2006), Mdegela et al.

(2009), (Kaya and Flazi 2010), Addo et al., (2011) reported low level of antibiotic

residues. However, Kurwijila et al. (2006) reported high prevalence of antibiotic

residues in a study conducted in Mwanza and Dar Essalaam, Tanzania; similar result

were reported by Shitandi, (2004) and Khaskheli et al. (2008). In Kenya, the problem of

high concentration of antibiotic residues in milk seems to be a threat to the health of

milk consumers (Shitandi, 2004; Kang’ethe et al. 2005; Omore et al. 2005).

Table 3:Antibiotic residues in raw milk samples obtained from different sources:

+vesample Number of sample Source of sample

0.00% 45 Farms

15.0% 45 Collection Center

4.4% 45 Groceries

4.4 Demographic characteristics of the study smallholder

This study aims at detecting the effect of society on milk quality included a survey using

questionnaires involved 50 participants from each category of milk vendors, milk

retailers and smallholder dairy farmers, the respondents composed of (100%)

males(Table 4), this result dis agree with Haile (2015) and Bukuku (2013), where

majority of the milk distributors were from villages (74.0%) and only (26.0%) were

from Wad Medani City (Table 4), the current results weresimilar to these of Bukuku

(2013).The respondents were of different educational levels. The Illiterates and

university educates each represents one third of the respondents while both primary and

secondary school formed the rest of respondents (about one third) as showed in (Table

4). The present study was in agreement with Ahmed and El Zubeir (2013), and El Zubeir

and Mahala (2011), who reported that higher illiteracy level (36%) was observed among

dairy farms owners' in the dairy camps in Khartoum State and that (22%) of them had

informal education. Bashir and El Zubeir (2013) reported that illiteracy among the cattle

herders in Kordofan State was found to be high (25%), while herders of the cattle with

primary and secondary school level certificates were reported to be (35.0%) and(

27.5%), respectively. However Hossain et al. (2006) reported that the majority of farm

owner's (60%) in Bangladish received higher secondary education level and the average

number of animal per farm was (13.01).

Table 4: Gender, location and educational level of respondents in the study area

Item Frequency Percent %

Female

Location

Village

Educational level

Illiterates

Primary level

Secondary level

Graduates

4.4.1 Dairy cattle breed

Crossbred cows of this studyrepresent the highest percent (68%) among the breeds in

the farms around Wad Medani city, this indicated that crossbred cows were best

adapted and predominated in the farms of Wad Medani and this result disagreed with

Ahmed and ElZubeir (2013), while the local type Butana and Kenana (20%,12%,

respectively). The overall range of milk produced by the different cows was between

(5-20 liters),(Table 5). This result is supported by Tibin et al. (1990) who found in

astudy of herd in Kuku dairy project farms that. 67.2% of the herd were up graded

cattle, 27.8% were local type and 4.9% constituted other types. The same finding

was also reported by Garciaet al.(2008) in parts of Uganda. Also Table 5 shows the

size of the dairy cattle herds ranged between 5 and 20 cows, however about 70% of

the dairy farms have between 5 to 20 cows and 32% of the farms have more than 20

Table 5: Breeds, milk yield and productive cows in the dairy farms

Type of breed

Crossbred

Butana

Kenana

Milk yield/cow

5 Liters(local)

5-10 L(few local)

11-20 L(crosses)

More than20 L(crosses)

Productive cows

5-10 cows

11-20 cows

More than 20 cows

Herd size

More than 30

4.4.1The cow milk handling practices by producers

As shown in (Table 6) all the smallholder dairy farms producers used to hand milk their

cows. Most of the producers milked their cows twice a day (46%) while 28% of the

respondents milked their cows in the morning and 26% milked their cows in the evening

(Table 6); this was because farmers wanted to harvest maximum milk from milking

herds and increase their income from sale of milk. This pattern of milking agree with the

findings of Byarugaba et al., (2003) and Twinamatsiko (2001). A similar finding was

also reported by Okwenye (1994) that dairy farmers in Uganda milked their herds twice

a day using hand milking. There was no cooling practices used for milk after milking,

the same findings were noticed by Ahmed and El Zubeir (2013). The main vehicles of

milk was car, which recorded 66% and cart which recorded (20%), while the other

means recoded only 8% (Table 6), this result is similar to the finding of Hussein(2008).

Table 6: General practices and milking process in some dairy farms:

Type of milking

Hand milking

Machinemilking

Cooling facilities

Time of milking

At morning

At evening

Twice a day

Transportation of milk

Other means

4.4.3Type of housing andhygienic practices

Ideal building materials was seldom used in dairy farms in the study area. All the

farmers in the study area used a traditional type of housing for their cows and the

milking is carried inside the pen; and some of dairy units are divided into fences for

different age groups of the cows. However, the traditional housing which consist of

fences of steel pipes and poses represent about (40%), above fence plus a shade

represent (22%), backyard housing represent (10%), while the pens which made of local

materials that consist of wood posts, sorghum stalks and thorn branches, represent about

(28%) (Table 7). Yousif and Fadl El-Moula (2006) reported that a traditional housing

system constructed from iron bars, corrugated iron sheets and other local materials such

as wood and hay is common, they added that the houses are partially shaded to

accommodate animals and to protect lactating cows from excessive sun and rain.

Similarly Mohamed (1995) reported that the building design should helps to reduce

environmental stress and provides safe and hygienic conditions to raise the level of

production to cover the additional cost. The manure removing is done routinely at

different intervals, which may be daily(12%), weakly (44%), monthly (22%), every 3

month(4%); while those removed the manure at other intervals represent(18%) as shown

in Table 7Abebeet al. (2012) and Haile(2015) also reported similar results.

Table 7: Types of housing and barn cleaning frequency

Pens Design

Shaded fence

Back yard

Others

Cleaning of the pens

Weekly

Monthly

Every three months

More than 3 months

4.4.4 Hygienic practices

The milker-man can be an important source of milk contamination; all of the

interviewed dairy producers (100%) washed their hands before milking; this result dis

agree with Bukuku (2013). Cleaning of cow's udder before milking is one of the most

important hygienic practices required to ensure clean milk production, however as

observed in this study (72%) do not wash the udder and simply allowed their calves to

suckle before milking (Table 8). Saliva from the calf mouth and unwashed teats may

increase the bacterial counts. Only 28% of the milkers used to wash the udder, as shown

in (Table 8), this agreed withHaile (2015) who reported a similar result. The current

result was lower than that reported by Haile et al. (2012) who reported that (82.5%) of

the small size farm in Hawassa city practice pre milking udder washing. Contrary to this

result Abebe et al.,(2012) who reported that all respondents did not use udder washing

before milking in Gurage Zone, Ezha district, Ethiopia.Containers used for milking and

for transporting the milk to collection centers and groceries mainly made of aluminum

(46%),Stainless steel(36%) and plastic (18%). Sources of water for washing utensils and

for udder cleaning is clean tap water from wells; (86%) of smallholder dairy producers

used to clean their milking utensil before and after usage, while (14%) of the producers

used to wash the milking utensils just before every use as shown in (Table 8). The

similar findings were noticed by Ahmed and El Zubeir (2013) and Haile (2015).About

(98%) of the producers used water and detergents to wash the milk handling equipment's

while (2%) of them use water alone, the current finding contradicts that of Haile et al.

(2012) who reported that about (85.6%) of the producers used warm water together with

detergents to wash milk handling equipment's. Therefore, it is important that producers

should at least filter the milk before marketing. Most of the grocers(86%) used to filter

the milk , while (14%) did not use to filter. 80% of the groceries used to filter the milk

with normal plastic filters at receiving milk from the farmers and before selling to

consumers, while (20%) of the farmers used cloth to filter the milk, (Table 8).All milkers

and farmers (100%) had knowledge about the causes of milk spoilage and knowledge

about mastitis. Farmers used different measures to control mastitis as shown in (Table

8). The present study found that all the respondents did not check for mastitis before

milking, but they can observed the abnormal milk constituents (blood clots, milk clots and

pus)As the result of lack of adequate on-farm treatments records the antibiotic

residues considered to be the highest factor followed by the lack of understanding

how to use antibiotics . In this study most of the farmers (70%) used to treat their sick

animals and only (30%) of the cases is handled by veterinarians as shown in (Table 8),

Similar study in Ethiopia (Syit, 2008) and Bukuku (2013) reported that the respondents

were aware of drug residue in milk following treatment of sick dairy animal.The main

sources of drinking water for dairy cows in Wad Medani area were artesian wells, canals

and Blue Nile river which represent (46%), (48%), (6%) respectively, (Table 8). Many

farms included in this study had no knowledge about water quality laws. Some of these

might be sources of contamination for milk with faecal organisms, the farm water supply

can be a source of microorganisms that can contamination for milk.

4.4.5 Raw milk marketing system

In the study area the milk sold to the consumers through different channels. Most of the

grocery stores (75%) receive the raw milk once a day while (25%) receive the milk

twice a day. About (85%) of the groceries filter the milk and (15%) do not filter (Table

9), the findings were in line with Kurwijila et al. (2006), and Bukuku (2013).Most of the

groceries (95%) boiled the milk before selling to consumers and (5%) did not, however;

in another studies by Kurwijila et al. (2006); Swai et al. (2010) and Kilango et al. (2012)

reported that boiling of milk prior to consumption is the best approach to prevent milk-

borne diseases especially in low income communities. Additionally (80%) used to cool

the milk before selling and (20%) do not cool the milk. Different cooling facilities were

used. (25%) used traditional means and ways, while (25%) used fans, and (30%) used

air conditioners, (10%) used refrigerators and (5%) use coolant. After milking proper

milk cooling method is essential to maintain the quality of milk. This result agreed

withHaile (2015).

Table 8: General hygiene and milking practices and water supply.

Washing Hand

Washing Udder

Milk Containers Aluminum

Stainless steel

Plastic

Cleaning of Milk

utensils Before and after milking

Only before milking

Cleaning with

detergents

Milk Filtration

Milk Filtration Tool

Knowledge about

mastitis

Mastitis Control

measures

Washing the udder with

cold water

Use of the udder ointment

Veterinary consultation

Others

Drugs usage

By farmer

By veterinarians

Water source

Canals

Rivers

The quality of milk as defined based on organoleptic characteristics (color, smell,

physical dirt and clotting). Results showed that most of the milk from smallholder dairy

farmers, had the normal yellowish white color. (55%) of the groceries used to accept the

milk always, while (45%) of the groceries used to reject the milk sometime. Reasons

behind the rejection of the milk are summarized in (Table 9), (50%) due to change in

color, (20%) due to change in aroma, (20%) due to addition of water, and (10%) due to

other reasons.Milk quality related constraints in the study areas can be summarized in

the followings: limited awareness on hygienic handling of milk, lack of cooling facility,

shortage of clean water, Lack of effective quality control system and absence of quality

based payment system.

4.4.6 Milk quality test in a collection center

The best way to manufacture milk with good quality is to start with a good raw material.

Testing raw milk is thus essential to ensure safety and quality. Raw milk is subjected to

analyses for alcohol test, addition of water, presence of antibiotics residues, and pH test

which are considered as major issue of milk quality criteria according to the milk which

can be accepted or rejected. Most (70%) of farmers had no knowledge about the tests of

the milk in a collection center, while 30%know as shown in (Table 10).

Table 9:Milk handling at the groceries.

Time of milk receiving

per day

Filtering of the milk

Boiling of the milk before

selling

Cooling of the milk before

selling

Cooling Facilities

Traditional cooling

Air condition

Refrigerators

Coolant

Milk Rejection

Reason for Rejection

Discoloration

Abnormal aroma

Watery milk

Others

Table 10: Milk quality tests conducted at Kafi collection center.

Test of the milk

Milk tests conducted

Acidity test

Antibiotic test

CHAPETRE FIVE

CONCLUSIONS AND RECOMMENDATIONS

5.1 Conclusion

Chemical and physical properties of the fresh milk varied slightly among the

different sources.

The traditional ways of milking and distribution of milk are still in used in the

Gezira state.

Some of the consumers received adulterated milk (addition of water).

Antibiotic residues were found in some of the distributed milk.

5.2 Recommendation

Awareness should be created through trainings of dairy cattle owners and

workers about the importance of hygienic practices of milking and milk

distribution.

Laws and rules and severe penalties and punishment should be applied

against those who adulterated milk through addition of water and antibiotic.

Incentives and higher prices should be given to hygienic production and high

quality milk.

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Appendix (1): The questionnaire used in Wad Medani for milker and

practiced in milk dairy farms and groceries.

بسم هللا الرحمن الرحيم

. معلومات عامه:1

................................................................................................................... :الرقم

.................................................................................................... المزارع اسم -1

أنثي -2 ذكر -1 :الجنس -2

قرية -2 مدينة -1 :الموقع -3

جامعي -4 ثانوي -3 أساس -2 أمي -1 التعليمي المستوي - 4

اللبن؟ توزيع مكان و ةالمزرع بين المسافة -5

دقيقة 90 من أكثر -4 دقيقة 90 - 60 -3 دقيقه 60 - 30 -2 دقيقه 30 - 15 -1

:التعامل مع الحلبكيفيه -6

يدوي -2 لي آ -1 :الحلب طريقة -1

صباح ومساء -3 مساء -2 صباح -1 :الحلب مواعيد -2

ال-2 نعم -1 ؟ مباشره الحلب بعد للبن تبريد يوجد هل -3

( حدد) خريأ -3 مبرد -2 ةثالج -1 التبريد؟ يتم كيف نعم اإلجابة كانت إذا

والقرية؟ المدينة داخل اللبن ترحيل وسيلة هي ما -4

عربيه -4 األقدام علي -3 الحمير علي -2 كارو -1

الحليب؟ اللبن إليها يوزع التي الجهة -5

أفراد -4 تجميع مركز -3 بقاالت -2 المتجولين الباعة -1

ال-2 نعم -1 التجميع؟ مركز في الحليب علي تجري اختبارات توجد هل -6

الكثافة اختبار -PH 2 ال اختبار -1 االختبارات؟ طبيعة هي ما بنعم اإلجابة كانت إذا -3

الحيوية المضادات جودة اختبار -3

للبقرة؟ اليومي الحليب إنتاج معدل -7

رطل 25 من أكثر -4 رطل 25 - 20 -3 رطل 20 - 10 -2 رطل 10 - 5 -1

بقرة 20 من أكثر -3 بقرة 20 - 15 -2 بقرة 10 - 5 -1 المنتجة؟ األبقارعدد -8

30 من أكثر -3 30 - 20 -2 20 - 10 -1 حجم القطيع بالمزرعة؟ -9

هجين -3 بطانة -2 كنانة -1 ؟األبقار نوع -10

خريأ -4

ترع -2 آبار -1 الشرب لألبقار؟ مصدر مياه -11

: نظافتها وكيفية الحظائر نوع -12

الحظيرة؟ نوع -1

أخري -4 المنزل داخل حوش -3 السياج داخل مظلة وجود -2 سياج -1

نظافة الحظيرة؟ -2

من شهر أكثر -4 مرة في الشهر -3 األسبوعمره في -2 يومي -1

الممارسات الصحية: -3

ال -2 نعم -1 ؟الحالبة قبل األيدي غسيل يتم هل -1

ال- 2 نعم - 1 الحالبة؟ قبل الضرع غسيل يتم هل -2

ال -2 نعم -1 الغسيل؟ بعد الضرع تجفيف يتم هل - 3

مناديل -2 قماش -1 تستخدم؟ ماذا بنعم اإلجابة كانت إذا

ترع -2 آبار -1 الحليب؟ وأواني الضرع لغسيل الماء مصدر -4

استيل -3 ألمونيوم -2 بالستيك -1 الحلب؟ في المستخدمة األواني نوع -5

وبعد قبل -3 الحالبة بعد -2 الحالبة قبل -1 الحليب؟ أواني غسيل يتم متى -6

فقط ماء -2 وماء صابون -1 ؟األواني غسيل كيفية -7

ال -2 نعم -1 مباشرة؟ الحلب بعد اللبن تصفية يتم هل -8

خريأ -3 قماش -2 مصفاة -1 : باستعمال التصفية تتم

؟ البن وفساد تلف سبابأ هي ما -9

( حدد) خريأ -3 األواني نظافة عدم -2 المباشر والتسخين التبريد عدم -1

ال –2 نعم -1 الضرع؟ بالتهاب خاصة مشاكل لديك هل -10

مرهم استخدام -2 الضرع غسيل -1 معالجته؟ كيفية هي ما -11

( حدد) خريأ -4 البيطري الطبيب استشارة -3

البيطري الطبيب بواسطة -2 المزارع بواسطة -1 : األدوية استخدام كيفية هي ما -12

ال -2 نعم -1 ؟األدوية استخدام في الصيدلي أو البيطري الطبيب بإرشادات تعمل هل -13

:العليقة تركيب -14

وموالص مبازأردة و -2 مباز أردة و -1 هي مكونات العليقة المركزة : ما -15

خري أ -4 ودريش مبازأردة و -3

الحالبة وقت -3 المساء -2 الصباح في -1 :العليقة تقدم متى -16

المستعمل في المزرعة:ما هو نوع العلف الخشن -17

1- 2- 3-

: التجميع ومركز البقاالت -18

مرتين -2 واحدة مرة -1 اللبن؟ تستلم اليوم في مرة كم -1

ال -2 نعم -1 االستالم؟ بعد مباشرة اللبن تصفية تتم هل -2

ال -2 نعم -1 االستالم؟ بعد مباشرة اللبن تسخين يتم هل-3

ال -2 نعم-1 البيع؟ قبل للبن مباشر تبريد يتم هل-4

خريأ -4 ثالجات -3 مكيفات -2 مراوح-1 اللبن؟ تبريد كيفيه هي ما

ال-2 نعم -1 ؟األحيان بعض في اللبن رفض يتم هل-5

طبيعية غير رائحة-2 طبيعي غير اللون -1 اللبن؟ رفض سبابأ هي ما

خريأ -4 مائي اللبن -3

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