Post on 05-Dec-2014
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Sheep Nutrition for ReproductionPart I: Nutrition as a Major Environmental Factor Affecting
the Reproductive Axis
J. Wamatu
EIAR-DBARC-ICARDA-ILRI (LIVES)-FAO Training on Reproduction in Sheep and Goat, Debre Berhan, Ethiopia, 13-15 October 2014
Jane Wamatu
Outline
Factors that influence feeding of an ewe Feeding regimes/stagesTypical nutritional disorders
Ewe Nutritional Needs are not Static
The objective of feeding the ewe is to produce lambs, whether these are for breeding, for fattening or for slaughter
Feeding an ewe depends on many factorso Ageo Weighto Body conditiono Stage and level of productiono Environmental factors and level of exercise
Ewe Nutritional Needs are not Static
The standard of nutrition for ewes can be classified into 3 main stages:
o Pre-breeding to breedingo Early gestation to mid gestationo Late gestation and early lactation
Pre-Breeding → BreedingThe level of nutrition in the weeks before mating and during the mating period is important in determining the number of lambs conceived
Aim Replenish body reserves lost after last pregnancy Minimize number of ewes which fail to show oestrus To ensure that a sufficient number of eggs are shed at ovulation and subsequently fertilized To maximize number of fertilized eggs which are implanted and develop into viable embryos and foetuses
Pre-Breeding → BreedingHow to achieve the aim Ewes are in appropriate body condition
at the beginning of the mating period The good body condition is maintained
for the first weeks of pregnancy when risk of embryonic mortality is greatest
Body condition scoring: Score 0 (emaciated) to Score 5 (very fat)
Pre-Breeding → BreedingHow to achieve the aim The better the body condition at mating, the higher is the ovulation
rate and the higher is the lambing percentage The number of eggs shed by ewes with a particular condition score
at mating depends largely on the breed Ewe lambs should be atleast 60 % of their expected mature
liveweight Ewes that are already in good body condition (3.5) do not generally
respond to flushing (current nutrition).
NB: In some breeds, ovulation does not respond to body condition
Pre-Breeding → Breeding The length of time required to prepare ewes for mating depends on
their initial condition and the quality of feed available (4 - >6 weeks) Attention should be paid to energy and protein intake Suggested quantities of energy are generally related to maintenance
of liveweight and specific rates of liveweight gain, rather than to changes in condition score
Approx. 1kg change in weight is equal to approx. 0.1 units in body condition
Pre-Breeding → BreedingSummary Ewes should be in proper body condition
by mating time – BCS 3.5 Lean ewes should be managed
separately for at least 6 weeks to ensure uniformity of flock condition at mating
Loss of weight or condition should be avoided during the mating period
Early → mid-gestationNutrition during pregnancy determines the number of lambs subsequently born alive with a birth weight which will ensure that they survive and are capable of growing well Placental development occurs first 30 to 90
days of pregnancy Placental size or weight affects nutrient
transfer between the ewe and her fetuses
Early → mid-gestationUnderdeveloped placentas result in low birth weights,
regardless of late gestation nutrition.21 days of severe underfeeding or 80 days of moderate
underfeeding can affect placental development.Do not overfeed or underfeed; aim for a body condition
score of 3 to 3.5
Nutrient requirements are only slightly above maintenance
Early → mid-gestation15-30% of eggs shed at ovulation fail to result in the birth of
the lambThe main reason is failure of embryos to implant in the first
month after matingSevere undernourishment or high levels of post-mating
nutrition may result in impaired embryo survivalEwes should maintain a constant weight during the month
following matingAvoid abrupt change in the level of nutrition
Early → mid-gestation It is important to maintain their weights over this period.
Prevent losses exceeding the equivalent of 0.75 units in condition score.
Protein requirements for growth are low, but should not fall below 10g CP per MJ of ME to ensure
Only small losses inbody condition should be allowed during this period
Even short periods of severe undernutrition must be avoided
Late gestation → early lactationNutrition after lambing has a major effect on milk production and hence on lamb growth rate
Proper feeding and management during late gestation are crucial to a successful lambing
During the last 4 to 6 weeks of gestation, 70 percent of fetal growth is occurring
Late gestation → early lactation The mammary system is developing. High output of protein in milk and colostrum production Additional undegraded dietary protein is required Protein sources relatively resistant to degradation in the rumen
are recommended The recommended rate of inclusion is influenced by their
degradability, potential production (milk) of the ewe and her ME intake
Late gestation → early lactation High output of protein in milk (colostrum production The ewe’s rumen capacity is decreasing. Nutrient requirement increase rapidly towards the end of
pregnancy and nutrient supply must be increased Lean ewes should be given preferential feeding For economy of feed use, ewes should be grouped according to
nutrient requirement e.g lambing date and age
Nutritional disordersHypomagnesaemia This refers to magnesium deficiency Occurs in the first 4-6 weeks of lactation at the peak of milk
production when there is a large demand of the very limited reserves of magnesium in the body
First sign of an outbreak is a dead ewe which appeared normal only a few hours earlier
An adequate intake of magnesium is ensured by including 6g of magnesium oxide evenly distributed in the daily ration of concentrate offered in early lactation
Nutritional disordersHypocalcaemia Also referred to as lambing sickness Occurs just before, during or just after lambing Ewes show uncoordinated movements, muscular tremors and
rapid breathing Ewes fall with the head and hind legs extended, rapidly develop
paralysis and go into a coma Treatment with calcium borogluconate solution generally results
in a rapid recovery
Nutritional disordersMuscular dystrophy Also known as white muscle disease Arises from deficiency in Vitamin E/selenium in the diet Symptoms are stiffness in young, rapidly growing lambs around
3-4 weeks Symptoms can also occur immediately after weaning at 4-6
weeks of age Main factors influencing amounts of vitamin E/selenium occurring
naturally in feeds are the type of soil on which the crop is grown, weather conditions during growing season and storage (high moisture storage leads to deterioration in their vitamin E status)
Nutritional disorders
HypomagnesaemiaFirst 4-6 weeks of lactation at the
peak of milk productionHypocalcaemiaLambing sicknessUncoordinated movementsMuscular dystrophyWhite muscle diseaseDeficiency in Vitamin E/seleniunStiffness in young, rapidly growing
lambs around 3-4 weeks.