A B S T R A C T S O F P A P E R S P R E ' S E N T E D A T T H E A N N U A L SOUTHEI%N D I V I S I O N A L M E E T I N G O F T H E

A M E R I C A N D A I R Y S C I E N C E A S S O C I A T I O N

Memphis , Tennessee

F e b r u a r y 4-6, 1963

F o r c e d convec t ion heat t ransfer coeff icients for five da i ry products. M. L. PEEPLES, Texas Technological College, Lubbock.

Experimental da ta were used to determine specific values for the forced convection heat t ransfer coefficients (h in b tu/hr , f t ~, F ) of five dai ry products during heating and cool- ing. The values at Reynolds Numbers of 10,000 and 100,000 are tabulated for 100 and 160 F. The relat ionships between the loga- r i thm of heat t ransfe r coefficient (h) and logari thm of Reynolds Number are linear, so tha t if one desires h values at Reynolds Num- bers other than 10,000 and 100,000, they can be determined by plot t ing data for each given temperature. Fur thermore , h values at tem- peratures between 100 and 160 1~ are propor- t ional to the difference between h at 100 F and h at 160 F.

The h values at Re = 10,000 and 100,000, respectively are :

Product h (heat) h (cool) Skimmilk (8.8% SNF)

100 F 750, 2,600 580, 2,200 160 F 490, 1,700 370, 1,400

Whole milk (3.8% F ) 100 F 680, 2,500 390, 1,700 160 F 440, 1,700 260, 1,100

10% milk (10% F) 100 F 590, 2,800 330, 1,400 160 F 380, 1,800 230, 890

25% cream (25% F) 100 F 550, 3,400 490, 1,800 160 F 390, 2,500 350, 1,300

40% cream (40% F ) 100 F 750, 5,500 160 F 530, 3,900

Comparison of methods of est imating re- gressions for the Orange-G method of milk prote in determination. C. P. BREIDENSTEI1% A. J. GUIDRY, AND J. E. JOHNSTON, Louisiana Agr icul tura l Exper iment Station, Baton Rouge.

Twenty-two monthly predict ion equations were obtained by regressing Kje ldahl protein equivalents of 336 fresh nfilk samples on eolorimeter readings of Orange:G determina- tions on the same samples. The regression coefficients obtained ranged from --.0058782 to --.018898. An a t tempt to combine the re- gression equations into a common predict ion

* Denotes author who presented the paper.

equation disclosed a highly significant (P < .01) difference among the monthly regression coefficients. A predict ion equation (~) = 8.3505 - - .019868X) was also obtained by regressing the Kje ldahl protein equivalent of powdered milk solutions containing 6, 5, 4, 3, 2, 1, and 0% protein on their respective Orange-G colorimeter readings. Significant month-to- month var ia t ion indicates the need for cau- tion in using a single set of determinations for the establishment of a s tandard curve for milk prote in evaluation, using the Orange-G dye-binding method.

Oxalic acid buffer for dye-milk protein de- t erminat ions . R. G. SEALS, * Tennessee A and I Sta te Universi ty, Nashville.

The effect of 0.05 M technical grade oxalic acid on the dye-binding capacity of individual cow's milk using both Orange G and Amido Black 10B dyes was studied. Reagent grade citric acid at concentration of 0.1 M was used as a reference buffer. Milk from twenty-one individual cows result ing in 84 samples ana- lyzed were used in the study with Orange G. Thirteen individual cows result ing in 52 sam- ples analyzed were used in the s tudy with Amido Black. The Orange G samples showed a significant difference between the mean dye- binding capacities (oxalate and ci t ra te) at the 10% level of probabil i ty . The Amido Black samples showed a significant difference at the 1% level of probabil i ty .

¥a lues of p i t between 1.5 and 2.0 appar- ently do not have an adverse effect on the dye-milk protein reaction. The lower p H seems to enhance dye-binding capacity.

Observations of the Orange G fil trates for several weeks indicated tha t oxalic acid is a good inhibi tor of mold growth. Since i t re- quires about s~ less oxalic acid than citric acid per unit volume of dye, oxalic acid is considered more economical, since the rea- gents do not differ grea t ly in price.

In ter re la t ionship b e t w e e n the major milk consti tuents of individual farm del iver ies . W. K. S~ONE, M. C. CONNER, A~D N. R. T~O~P- SON, Virginia Polytechnic Inst i tute , Blacks- burg.

Deliveries of bulk milk to ten different p lants from 600 individual farms were ana- lyzed during summer and winter for total solids (T.S.), protein, and fat . Determinations of f a t were by Babcock in each plant ' s lab-

359

360 J O U R N A L OF D A I R Y S C I E N C E

oratory. At ¥.P.I. , T.S. were determined by drying in a forced-air oven; total protein was by direct steam disti l lation of the alkaline milk sample. Solids-not-fat (SNF) was T.S. minus fat, and lactose-mineral (L.M.) was SNF minus protein.

The SNF, protein, and fat averaged, re- spectively, 0.07, 0.17, and 0.20% higher in winter, but the relationships between SNF and fat and between protein and fat were not affected by season. For the combined summer and winter results (1,200 samples), correlations between SNF and fat and be- tween protein and fat were, respectively, 0.60 and 0.72. The fat varied from 2.9 to 5.9, average 3.9%; SNF from 7.7 to 9.7, average 8.66%; protein from 2.8 to 4.2, average 3.29%; and L.M. from 4.7 to 5.9, average 5.4%. For each 1% increase in fat the SNF and protein increased, respectively, 0.42 and 0.35%. The L.M. did not increase with increases in either fat or protein.

Persistence of cooked flavor in milk pas- teurized at 194 F. B. J. DE~o~z, University of Tennessee, Knoxville.

Milk from the regenerator section of a HTST pasteurizer at 130 F was exposed to a vacuum of 20" Hg, passed through the heater section, through a flow-diversion valve set to divert at 194 F, then into a vacuum chamber, where the milk was cooled immediately to 160 F. The holding time between the outlet of the heater to the flow-diversion valve was 5.5 sec. After homogenizing and cooling, the milk was stored at 4 0 F unti l just before tasting. Four experienced milk judges scored blind samples each day for nine days. A total of 302 flavor evaluations was made on 82 samples. The data indicate that the cooked flavor of milk on the fifth day after pasteuri- zation was less pronounced, and on the n in th day after pasteurization was more pronounced, than on the same day of pasteurization. The nitroprusside values were two for the first five days and one on milk stored longer than five days after pasteurization.

Relationship of phospholipid content and fatty acid composition to milk fat hydrolysis. J. H. GHOLSON* AND W. R. WALLACE, Louisi- ana Agricultural Experiment Station, Baton Rouge.

To provide maximum variation in the study of these relationships, this experiment was divided into two periods, the first in April and May, the second in August and September. The design of the study included the random selection of eight Holstein and eight Jersey cows for each period. Samples of the whole evening milking were collected at biweekly intervals from the milker pM1. One was im- mediately pasteurized for determination of spontaneous acid degree values (ADV) and one was cooled to 4 C and held for 48 hr for

developed ADV. Phosphatide content and fat ty acid composition determinations were made on each sample by the methods of Green- bank and Pallansch (J. Dairy Sci., 44: 1597. 1961.) and Smith (J. Dairy Sci., 44:607. 1961), respectively. Data pertaining to breed, age, lactation number, production, and ration were collected.

For all samples the ADV increase ranged from 0.025 to 9.43, with a mean of 1.17 and a standard deviation of 1.275. Phosphatides ranged from 0.178 to 1.365 g/100 g fat, with a mean of 0.643 g/100 g fat and a standard deviation of 0.350 g/100 g fat. The mean ADV increase for Holsteins was 1.362 and for Jerseys 1.007. For Period One, the mean ADV increase was 1.266 and for Period Two, 1.074. Phosphatide content in both periods for Holsteins was 0.6851 g/100 g fat and for Jerseys, 0.589 g/100 g fat.

Relationship of milk pipeline height to in- creases in acid degree values. W . R . WALLACE ~ AND J. H. GttOLSON, Louisiana Agricultural Experiment Station, Baton Rouge.

Agitation of milk during milking has been related to increases in acid degree values (ADV) of milk fat.

To determine the effect of pipeline height, a simulated udder comprised of four calf nipples attached to the flat bottom of a 14-qt milk pail was used in the experiment. Milk was t ransferred by plastic tubing from the milker claw to a standard pyrex milk pipe- line 6 f t in length. A 5-gal milker pail was attached to the end of the pipeline to serve as a milk receiver and a point for sampling. The simulated udder was milked with and without milker pails. The pipeline heights were adjusted in 2-ft increments from --2 f t below the udder to 6 f t above. Warm, un- cooled, pooled milk from three Holstein and three Jersey cows milked with bucket milkers located approximately on a level with the udder was used for the experiment. For each pipeline height 5 lb of milk was pumped through the system. Samples were taken from the receiver pail, one immediately pasteurized for determination of spontaneous ADV and one cooled to 4C and held 48 hr for devel- oped ADV. The experiment was repeated without milker pails, using four Holstein cows in a Latin-square design over four days through four pipeline heights of --2 ft below the udder to 4 f t above in 2-ft increments.

In the simulated system with milker pails, the following 48-hr increases in ADV over spontaneous values were noted: 0.33 for --2 ft, 0.27 for 0 ft, 0.190 for + 2 ft, 0.198 for + 4 ft, and 0.22 for + 6 ft. Results on the system without pails were: 0.24 for --2 ft, 0.19 for 0 ft, 0.16 for + 2 ft, 0.14 for + 4 ft, and 0.21 for + 6 ft. Differences in heights

ASSOCIATION AFFAIRS 361

were statistically significant ( P < .01), as well as differences between systems (P < .05).

Results of the experiment with cows gave the following increases in 48 hr over spon- taneous values: 0.70 for --2 ft, 0.43 for 0 ft, 0.62 for + 2 ft, and 0.42 for + 4 f t . Differ- ences in heights were statistically significant P < .011).

Natural variation in the freezing l~oint of milk from one herd. R. W. HENNINGSON, Clem- son College, Clemson, South Carolina.

The freezing point value of the milk from the South Carolina Agricultural Experiment Station herd of 225 cows was investigated for two years, util izing daily samples of well- mixed Ps~-~ milk from a holding tank. Pre- cautions were taken to minimize residual moisture in equipment before milking and to prevent rinse water from entering the tank.

Freezing point values were determined for 579 daily milk samples by the Hortvet method. The unweighted average freezing point value was --0.537 C for the 2-yr period. Annual unweighted average freezing point values were --0.540 and --0.533 C. The freezing point value range over the 2-yr period was 0.032 C (--0.519-0.551C). At present, the unweighted average freezing point value of milk from this herd is --0.530 C. No seasonal differences were observed. Annual turnover of animals within the herd was approximately 33% during the 2-yr period.

Statistical analysis of the data, utilizing analysis of variance and calculated F value techniques, indicates significant differences, at the 1% level, between days, weeks (-days), months (-days and weeks), and years (-days, weeks, and months).

Enumeration of citrate-fermenting bacteria in commercial lactic cultures. W. W. OVER- CAST AI"~D J. D. SKEAN, University of Tennes- see, Knoxville.

The medium of Galesloot et al. for isolating and enumerating the armna bacteria of starters was altered by substi tuting tomato juice agar (TJA) for the whey agar and the casamino- acids. The calcium lactate to inhibit the streptococci and the colloidal calcium citrate for an indicator of the citrate-fermenting bac- teria were retained and used in the TJA. This medium, in addition to M-PH and TJA, was used to enumerate the lactic acid and the citrate-fermenting bacteria in 72 cultures. The 72 cultures were obtained from 41 dairies, where they were used for Cottage cheese, buttermilk, sour cream, and Cheddar cheese making. Colony counts on the TJA were higher than on the M-PH agar. Colony counts of citrate-fermenting bacteria per milliliter, expressed as per cent of each corresponding count in TJA, ranged from ~ 0.0076 to 730%. The median per cent of citrate-fermenting bacteria in the cultures was 12.6%.

Influence of milk fractions on activity of lactic cultures. It. C. 0LSON AND S. E. GILLI- LAND, ~ Oklahoma State University, Stillwater.

Whole milk, skimmilk, cream, butter, milk fat, buttermilk, and separator slime from sev- eral lots of milk were studied for their in- fluences on the rates of acid production by lactic cultures. These were used alone and in combinations with skimmilk or reconsti- tuted nonfat dry milk. Portions of the milk media were heated to 160, 180, and 200 F for 30 rain before inoculation, to determine the influence of these materials on the damaging effect of heat on the milk.

Unhomogenized and homogenized whole milks supported more active lactic production than skimmilk after heating to 160 or 180, with no difference in the lots heated to 200 F. Cream depressed acid production, whereas butter and milk fat appeared slightly to favor it. Buttermilk was inferior to skimmilk, but when these two were combined acid produc- tion was accelerated. "Buttermilk" from washed cream was also stimulatory when added to skimmilk, although the solids con- tent was very low. Separator sediment re- constituted to the same solids content as skimmilk appeared to be very stimulatory when mixed with skimmilk. The apparent st inmlatory effect of the fractions of milk may be due in par t to a lessening of the dam- aging effect of heat on skimmilk.

The effect of refreezing techniques on ac- t iv i ty of frozen lactic cultures. JoE T. CARD- WELL, Mississippi State University, State Col- lege.

Frozen ripened intermediate cultures have been used successfully in the Mississippi State Universi ty dairy plant for 10 years. Success has been experienced with both the fast and slow freezing methods used. Higher solids milk has offered protective action to the cul- tures under the conditions of extended stor- age (more than 30 days). I t has been ob- served that for best results frozen cultures must be thawed in fresh culture medium with a minimum concentration of metabolic bi- products. Results indicate that frozen cul- tures cannot withstand heat shock of tempera- tures near melting point of culture. Also, certain first generation cultures may be re- peatedly frozen at periodic intervals without adverse effect on activity or coagulating prop- erties. However, repeated freezing failed to eliminate contaminants from certain cultures when commercial conditions were sfinulated. Contaminants present in the culture persisted after 15 repeated freezings under these con- ditions. Whether or not repeated freezing of cultures held at lower temperatures will elim- inate contaminants is being investigated.

362 JOURNAL OF DAIRY SCIENCE

Selective plating technique for detecting contamination in pasteurized milk. H. C. OL- soN, Oklahoma State University, Stillwater.

A selective plating technique was developed for detecting contamination subsequent to pasteurization. I t involves adding 1 ppm crystal violet to Standard Plate Count agar before sterilization and 50 ppm 2, 3, 5-tri- phenyltetrazolium chloride to the agar just before pouring the plates. The plates are incubated at 90 F for two days before count- ing. With low dilutions (0.5 ml per plate) the relatively large amount of milk partially neutralizes the effect of the crystal violet. This is overcome by diluting 9 ml of milk with 9 ml of sterile water containing 10 ppm of crystal violet. One milliliter of this mixture is added to each of two plates and the total count on the two plates represents the con- tamination per milliliter.

Contaminating colonies are distinctly red. Very few organisms surviving pasteurization occur on the plates and they are generally very small and uncolored or lightly colored.

The test has been applied to several hun- dred samples of milk at various stages of processing and the results compared with the standard plate, coliform, and psychrophilic counts as well as shelf-life. The technique, designated CVT Count, appeared to be more reliable than the other methods for detecting contamination and for predicting shelf-life.

Spoilage of milk by thermoduric psychro- philes. H. C. OLso~, Oklahoma State Univer- sity, Stillwater.

Several bacterial cultures which survive ordinary pasteurization (161°-16 sec) have been isolated from samples of milk held at 45 F for determination of shelf-life. After purification, the cultures were tested for sur- vival at 161°-16 see and for their effect on the flavor of milk stored at 45 F. I t appeared that at least four types of thermoduric organ- isms can cause spoilage at 45F. The most common defects produced were fruity, un- clean, bitter, and sweet curdling, followed by bitterness. The organism encountered most frequently caused a pronounced f rui ty odor and flavor. Fur ther research is in progress to identify the organisms.

While the thermoduric psychrophiles can cause spoilage of pasteurized milk, it ap- peared that they are not numerous in milk supplies and are generally encountered only in milk having long shelf-life due to the ab- sence of post-pasteurization contamination with the organisms usually responsible for spoilage.

Effect of inorganic nitrogen sources on the growth of various pseudomonads. C. YANDER- ZANT A/~rD A. E. BARDIN, Texas Agricultural Experiment Station, College Station.

Ten inorganic N sources were tested for their ability to serve as sole source of N (0.15 mg N per milliliter medium) in a glucose-salt medium for six strains of Pseudomonas fluo- reseens, 12 strains of Pseudomonas fragi, and ten strains of Pseudomonas putre/aciens. In- organic N substrates were more readily utilized by P. fluorescens than by P. fragi. The ma- jority of the strains of P. putrefaciens did not grow with inorganic N sources as sole source of N.

Taxonomic studies on lipolytic aerobic spore- forming bacteria from milk. M. A. HOL~AR ~ AND EARL R. GARRISON, University of Arkan- sas, Fayetteville.

Milk delivered to dairy plants was heated to 85 C for 15 min, then plated on Nile Blue sulfate fat emulsion agar to isolate the lipo- !ytic spore-forming organisms. Two hundred thirty-nine aerobic motile rod cultures with varying gram reactions were purified and studied.

No culture grew at 55 C, all grew at 40 C, and only two grew below 10 C. All hydrolyzed casein and gelatin, and produced tt~S.

Fermentat ion studies using 1% concentra- tions of 25 carbohydrates were made in two media. Nutr ient broth (0.4% yeast extract, 0.6% trypticase, bromeresol pm-ple) was incu- bated under aerobic conditions, and semisolid agar (0.2% peptone, bromthymol blue) was incubated under aerobic and anaerobic condi- tions. The 0.2% peptone, bromthymol blue medium was more sensitive to acid production. Anaerobic incubation facilitated separation of fermentative and oxidative acid production.

The following factors were also used in differentiation: (1) nitrate reduction; (2) maximum salt concentration permitt ing growth; (3) maximum and minimum growth temperatures; (4) action in litmus milk; (5) gelatin liquification rate; (6) pH produced in glucose broth under anaerobic conditions; (7) growth in Koser Citrate medium; (8) tysis of red blood cells; (9) extent of fat hydrolysis in both sweet and lactic culture inoculated cream.

The cultures were divided into four d~stinct groups. One group was tentatively identified as B. cereus (31 cultures) and one as B. eir- culans (five cultures); 203 cultures were in- completely identified.

Relationship between soluble nitrogen and bitter flavor in Cottage cheese. D. M. NA~F AND W. I~. STONE, Virginia Polytechnic In- stitute, Blacksburg.

For ty Cottage cheese products from 20 dif- ferent brands in Virginia markets during the summer of 1962 were evaluated for flavor and analyzed for soluble nitrogen. Flavor was scored by the A.D.S.A. Guide. Total nitrogen was determined by the Kjeldahl method and

ASSOCIATION AFFAIRS 363

soluble nitrogen by the procedure described in the J. Dairy Sei., 45:286. 1962.

The predominant flavor of each product, and per cent of products having each flavor, were: sl ightly bit ter , 25.0%; definitely bi t ter , 20.0%; foreign, 15.0%; fermented, 12.5%; acid, 10.0%; and excellent (score of 39 4 ) , 17.5%. The average soluble nitrogen expressed as per cent of totM nitrogen for each flavor was: 5.97, 6.40, 4.65, 4.66, 5.81, and 4.70%, respectively.

The products having a b i t ter flavor were higher in soluble nitrogen than the nonbitter . The presence of other flavors interfered in some instances with detection of bitterness. Fo r all of the b i t te r products, the average soluble nitrogen was 6.17%; for all nonbit ter , 4.88%.

Mechanical salting of Blue cheese curd at hooping. J. J. JANZEN, South Carolina Agri- cultural Exper iment Station, Clemson.

During the continuous hooping operat ion for Blue cheese the curd and whey mixture is pumped into the upper end of a sl ightly in- dined, rotat ing, perforated, cylindrical drum. The whey drains off freely, the curd is pro- pelled forward and deposited on to a sloping chute. As the curd moves down this chute, a specially designed auger agi tates the curd while a salt-mold mixture is metered on to this curd stream. While the salt acts as a distender for the mold powder, it is possible to step up the salt addit ion to such an extent as to retain approximate ly 1% within the hooped curd.

The meter ing device was described in the J. Dairy Sci., 45:649. 1962. This system has worked remarkably well for mold dis- pensing and offers an ideal opportuni ty for pa r t i a l ly sal t ing the curd. Data will be pre- sented showing the extent of sal t addit ion possible at this stage and the amount re- tained in the hooped curd. Salt incox2ooration at the hooping stage reduces the amount of subsequent salting, thus saving on labor.

Taste panel studies of a low-fat spread. J. B. MICKLF,, ~ MARY E. LEIDIGH~ ~/[ARY V. MALKUS, n. D. MORRISON, HAZEL D. BAKER, AND R. L. ~ON GUI~TEIW, Oklahoma State Uni- versity, Stil lwater.

Milk fa t f rom 92-score but ter was solidified into but ter l ike spreads containing 60-80% fat , 2% NaC1, It:O, and no emulsifier. But ter- like products containing 30-60% fat , 2% NaC1. and H..O also were produced with the aid of water- in-fat type emulsifiers. These products were evaluated by a taste panel of eight women. Low-fat samples (containing 40, 50, or 60% milk fa t ) were compared to control samples (but ter containing 80% untrea ted milk fa t ) and to two brands of margarine. Samples containing 80% rearranged milk fa t and 80% untrea ted milk fa t plus emulsifier

also were evaluated by the panel. A paired- comparison type design was used and four samples were evaluated at each tas t ing period.

No difference was detected between the taste of control samples and those containing 80% rearranged milk fat. About half the time the panel could not dist inguish the low- fa t samples from the controls. When prefer- ences were expressed, they were in the order of : controls > low-fat samples > margar- ines.

Solidification temperatures of various fat- water mixtures cooled at different rates. J . B . MICKLE, ~:~ M. H. BEAUFORD, AND L. C. TRV~, Oklahoma State University, Sti l lwater.

Inflections in curves of cooling rates vs. times for t r i laur in-water mixtures and fluid milk products, relat ive to similar curves for water, indicated solidification temperatures of the fat. The t r i laur in data are shown below:

Solidification temperatures of t r i laur in C

% T r i l a u r i n Cooling ra te C/min

in water 0.1 1.2 2.4

39 44 43 41 4 41 38 35

F lu id milk products containing 39, 20, and 4% fat , plus 20% NaC1 in the water portion, were cooled and the da ta were evaluated in a manner similar to that used for tr i laurin. The average solidification ranges for milk fa t in these products were: Average solidification temperature ranges of

milk fa t C

Cooling ra te

C/min % Milk fa t

39 20 4 1.2 ] 7 t o 3 16 to - -3 10 to - -5 2.5 15 to - -4 14 to - -6 6 to - -2

Consumer preferences for sugar levels in ice cream and frozen desserts. IV. Corn syrup solids replacement levels in chocolate ice cream. J. J. SHEURING AND E. J. FINNE- GAN/' Universi ty of Georgia, Athens.

A household consumer panel of 977 indi- viduals was conducted in February , 1961, to measure preferences for varying 42 D.E. corn syrup solids replacement levels (0, 5, 10, 15, and 20%) in chocolate ice cream with 18% sweetness.

Samples of the chocolate ice cream samples were dispensed as they would have been in a supermarket . Panel is ts were asked to fill out a questionnaire for flavor and texture prefer- ences for pa i red samples.

Result ing preferences, excluding no-prefer- ence responses, were analyzed s ta t is t ical ly with the method of rank analysis of incom-

364 JOURNAL OF DAIRY SCIENCE

plete block designs. Unequal repet i t ions on pMrs indicated that the consumers' flavor pref- erences (5% level) were for the two lowest 42 D.E. corn syrup replacement levels (0 and 5%) over the three higher replacement levels (10, 15, and 20%). The 10% replacement level was prefer red over the 15 and 20% re- placement levels. Texture preferences showed that the 5% level of 42 D.E. corn syrup solids was prefer red over 10 and 15% levels.

Consumer preferences for corn syrup solids replacement levels in vanil la ice cream. J. J. SHEURING AND E. J. F I N ~ E G A ~ , ~'~ Universi ty of Georgia, Athens.

To determine the react ion of consumers to varying 42 D.E. corn syrup solids replacement levels (0, 5, 10, 15, and 20%) in vanil la ice cream, a household consumer panel, with 992 individuals, was conducted in January , 1961.

Samples of the vanil la ice creams (18% sweetness) were dispensed as they would have been in a supel~larket. Panelists were asked to fill out a questionnaire for flavor and tex- ture preferences for paired samples.

Result ing preferences, excluding no-prefer- ence responses, were analyzed s t a t i s t i c a l l y with the method of rank analysis of incom- plete block designs. Unequal repet i t ions on pai rs indicated that the consumers' flavor preferences (5% level) were for the three lowest 42 D.E. replacement levels (0, 5, and 10%) over the two highest replacement levels (15 and 20%). The 10% replacement level was prefer red over the 15% replacement level. Texture preferences showed that the four lower replacement levels were prefer red (5% level) over the 20% corn syrup solids replace- ment level.

Nutritional evaluation of permanent pas- tures during the summer months with lactat- ing cows. A. S. ACHACOSO, L. L. RUSOFF, CECIL BRANTON, B. R. FARTHING-, AND J. L. FLETCtIEU, Louisiana Agricul tura l Experiment Station,~ Baton Rouge.

The lignin, crude protein, and gross energy contents and digest ibi l i ty of herbage, pasture quant i ty and quali ty scores, and milk produc- tion were used to evaluate permanent pas- tures from Apr i l through September.

Cows received permanent pasture as the sole source of forage, plus a concentrate al- lowance based on individual production. One group o$ cows fed an optimum diet of good- quality a l fa l fa hay and grain served as the control.

The average crude protein content of pas- ture herbage decreased significantly (P < .01) from 21.64% in Apr i l to 13.38% in August, with the greatest decline between Apr i l and June ; lignin increased significantly (P < .01) from 4.36% in Apr i l to 7.96% in July, fol- lowed by a significant decline in August to

6.40%. The gross energy values ranged from 4,331 to 4,440 calories per gram and remained fa i r ly constant throughout the period.

The digest ibi l i ty of pasture herbage was higher during the ear ly par t of the growing season (Apri l to May) , followed by a sig- nificant decline (P < .01) during mid-summer (June to Ju ly) , then a slight increase in the la ter par t of August. Similar trends were obtained in the average pasture quali ty score and the average dry mat te r intake by cows. I I ighly significant correlation coefficients were obtained between these measures.

Highly significant positive correlations were obtained between quali ty score and crude protein, quali ty score and gross energy, and between crude protein and gross energy; whereas, those between quali ty score and mean daily temperature, and quali ty score and lig- nin, were negative at P < .01. These variables were also found to be highly correlated with herbage digestibili ty.

Alfa l fa grazing and its contribution to pas- ture mixtures for dairy cows. W. R. MURLE¥, H. D. GROSS, AND R. M. SHAW, North Carolina Agricul tura l Exper iment Station, Raleigh, AND C. W. WALKER, Piedmont Research Station, Salisbury.

Twenty-four acres were grazed for four years by lactat ing cows and dairy heifers to measure the product iv i ty of various pasture mixtures and systems of grazing. The follow- ing species of forages replicated three times were seeded in 1958 and grazed during the next four summers: 1. Ladino clover-orchard grass (two acres) ; 2. Ladino e love~orchard grass (one acre) and a l fa l fa (one acre) ; 3. Ladino clover-orchard grass (one acre) and a l fa l fa -o rchard grass (one acre) ; 4. orchard grass (two acres). Treatments 1 and 4 were grazed continuously, whereas 2 and 3 were grazed in a system whereby the a l fa l fa and a l fa l fa -orchard grass, respectively, were strip- grazed froru four- to seven-day periods and then the Ladino clover-orchard grass plots were grazed continuously until the a l fa l fa had recovered. Reserve pastures of either Ladino clover-orchard grass or orchard grass alone were used when the cows were not on the plots. Concentrates were fed at the rate of 1:6 daily for 4% FC3~. Results for 1959 were reported in proceedings of A.S.A.W., page 113, 1960. The t reatments yielded during the subsequent 3-yr per iod an average of 2,207, 2,342, 2,327, and 2,264 lb TDN per acre, re- spectively, and the cows averaged 43.9, 42.5, 42.8, and 39.7 lb I~C3/[ per day during the graz- ing period. The TDN harvested for milk as a per cent of the total TDN were 63.4, 65.2, 68.5, and 60.7%, respectively. No stat is t ical sig- nificance was exhibited in any of the meas- urements.

ASSOCIATION AFFAIaS 365

Influence of feed additives on the uti l ization of Coastal Bermuda and oat hays by dairy heifers. W. A. KIN~, ~ C. C. BRANN01% AI~D I-I. J. WEBB, South Carolina Agricul tura l Ex- per iment Station, Clemson.

The influence of cottonseed meal, a l fa l fa meal, and molasses on ut i l izat ion of Coastal Bermuda hay and oat hay cut in bloom, milk, and early dough stages was studied by di- gestion and balance tr ials with bred dairy heifers. On a dry mat ter basis the Coastal hay contained almost twice as much protein and less crude fiber than the oat hays. Be- cause of the lower protein content of oat hay, cottonseed meal was fed as a par t of the basal ra t ion With these hays. The Coastal and dough-stage oat hays were mere pala table than the other two.

The Coastal hay supplemented with cotton- seed meal was significantly higher in digesti- bi l i ty of dry matter , protein, fiber, and N F E and TDN over hay alone. Molasses additive increased digest ibi l i ty of dry mat te r and NFE and TDN with both Coastal and dough oat hays. Al fa l fa meal-dough oat hay rat ion was higher in digest ibi l i ty of dry matter , protein, fiber, and NFE and TDN than the basal. An increase of digest ibi l i ty of protein, fiber, and TDN was found for a l fa l fa addit ive over molasses. No differences between the bloom- and milk-stage oat hay rations were found. Good retention of nitrogen, calcimn, and phos- phorus was found in all trials.

Effects of age at catting and weathering on Coastal Bermudagrass hay. J. C. JOHNSOn, JR., ÷:~ D. ~V. BEARDSLEY, G. %V. BURTON, F. E. KNOX, AND B. L. SOUTHWELL, Georgia Coastal Pla in Experiment Station, Tifton.

Three Coastal Bermudagrass hays obtained from similarly t rea ted sods were: (1) har- vested a f te r a growth inte~wal of 32 days and baled af ter lying in swath for two days with- out rain, (2) harvested af te r a growth inter- val of 32 days and baled af te r lying in swath for seven days and 0.77 in. of rainfal l , (3) harvested af te r a growth interval of 56 days and cured in wagons with heated air. When fed, hays (1), (2), and (3) contained 75, 64, and 55 % leaf material , respectively. Chemical analyses indicated that weathering resulted in loss of total available carbohydrates and dry matter , pr incipal ly in the leaves. Increas- ing the growth interval decreased crude pro- tein, ether extract and increased crude fiber, cellulose, and lignin content of the hay.

F i f t een lactat ing cows were fed the three hays for a comparison period of 41 days. In- take of (1) was 7.6 and 22.1% greater , re- spectively, than that for (2) and (3). Al- though intakes varied considerably, only that of (1) and (3) differed significantly. Cows fed (1) produced 12.1 and 8.6% more milk, respectively, than those fed (2) and (3).

These were highly significant differences. Milk production from (2) and (3) was not different.

The data show that var ia t ion in age of grass when cut and method of curing have impor tant effects on the ut i l izat ion of Coastal Bermuda hay by lacta t ing da i ry cows.

Lactation response of cows to rotational and alternate day and night grazing of Coastal Bermudagrass and mil let pastures. G. H. ROLLI¢,~s AND CARL S. HOVELAND, Auburn Uni- vers i ty Agricul tura l Exper iment Station, Au- burn, Alabama.

Lactat ion of cows grazing Coastal Bermuda- grass and Gahi-1 millet a l te rnate ly on a day and night basis was studied in a randomized block design repl icated six times. Average dai ly FCM per cow during the s tandardiza- tion period was 37 lb in 1959 and 42 lb in 1960. Experimental period for 1959 was June 26-September 17, and for 1960 was May 31- September 5. Rate of concentrat e feeding was

"approximately 1 lb per 4 lb of FCM. Three subpaddocks were grazed rotat ional ly, 1 wk of a 3-wk cycle, cl ipped immediately with a ro ta ry mower, and 50 lb per acre of nitrogen applied. Height of cl ipping Bermuda was 8 in. in 1959 and 4 in. in 1960, and of millet I 12-14 in. Supplemental i r r igat ion was applied.

Milk production of cows confined to millet and that of the a l te rna te ly grazed cows was similar both years, declining at approximate ly 6% per 4-wk per iod; production of cows con- fined to Bermuda declined 12% during 1959, as compared with 6% during 1960. Forage disappearance measures revealed that al ter- nat ing cows consmned large quanti t ies of both forages. Digest ibi l i ty of the forages for 1960 (determined by chromogen-chromic oxide method using nine heifers, four collection periods) was 65, 71, and 68% for Bermuda, millet, and Bermuda-millet , respectively.

Nutrient losses and chemical changes of Coastal Bermudagrass when ensiled at two stages of maturity. W. J. MILLER, ~ C. M. CLIFTON, AND ~. W. CAD£ERON, Universi ty of Georgia, Athens.

In a study of the effects of physiological stage on its ensiling characteristics, two rep- lications of Coastal Bermudagrass in the a) pre-head and b) ful l-head stages were rapidly ensiled in 8 by 24 f t tower silos. One hundred lb of ground corn gra in was added per ton of forage. The younger forage contained more protein, but fiber and dry mat te r levels were not affected appreciably by stage at "harvest. Silages from the pre-head and full-head Coastal had the following, respect ively: p H 5.2, 5.3; ammoniacal N (as % of crude pro- tein) 27, 29; dry mat te r 30.8, 31.7; crude fiber 30.9, 30.7; and crude protein 12.9, 10.5. Organic acid levels were low in all silages with averages on a dry basis for pre-head and full-head materials of; butyr ic 0.7, 1.0; acetic

366 JOURNAL OF DAIRY SCIENCE

1.0, 1.2; lactic 1.9, and 1.1; and total 4.2, 4.1. Higher fermentat ion and spoilage losses were observed with older material. Calculated as percentages of forage nutr ients ensiled, recov- eries from the pre-head and full-head silages were: dry mat ter 87.4, 73.6; crude protein 79.2, 68.6; and NFE 79.9, 67.6. Temperatures during ensiling were not greatly different, with peak values of about 104F.

Influence of stage of maturity on the nu- tritive value of Sudan grass. 0. T. STALLCUP, ~ AND G. V. DAVIS, Arkansas Agricul tura l Ex- perinlent Station, Fayet tevi l le .

P iper Sudan grass was harvested and fed ad lib. to three Holstein steers at three stages of growth: 18-24 in. high (June 30-July 8) ; 36-48 in. high (July 14-25) ; and boot to early- head stage (Ju ly 26-August 5). Approximate analyses (per cent) for the three stages of growth in the order listed above were: crude protein, 16.8, 12.8, and 9.7; crude fiber, 24.1, 31.1, and 34.7; ether extract, 3.8, 3.2, and 2.9; ash, 11.1, 7.0, and 6.3; N.F.E., 44.3, 44.8, and 46.6; cellulose, 26.8, 33.1, and 34.9. The coeffi- cients of digestion of nutr ients (per cent) for the three stages of growth in the order l isted above were: D.M., 70.9, 71.6, and 67.7; crude protein, 76.4, 71.3, and 58.0; crude fiber, 85.0, 75.7, and 73.6; ether extract, 76.7, 80.6, and 78.8; N.F.E., 82.5, 71.5, and 67.5; cellulose, 86.6, 79.9, and 74.8; energy, 78.5, 70.1, and 65.7. The TDN for each of the three stages in the order l isted above was: 76.4, 71.5, and 67.7.

Dwarf corn for silage. DEt~O S. Ra~[sEY, Mississippi State University, State College.

Six heifers, averaging 750 lb in weight, were fed in a 3 × 3 Latin-square design t r ia l three silages, A. Sudax (sorghum and Sudan cross), B. dwarf corn, and C. Dixie 55 corn. Consumption per 100 lb of body weight, di- gest ibi l i ty of d ry matter , and digest ibi l i ty of protein for A, B, and C, respectively, were 1.00, 1.50, 1.42 lb; 52, 60, 63%; 28, 56, 52%. Differences between normal and dwarf corn were not significant. Dry mat te r losses for A and B in 6- by 20-ft concrete silos by the buried bag technique were 10 and 8%, respec- tively. Silage C was made in a large upr ight silo. Yields in tons per acre were A--11, B- - 19 (26,000 p lan t s /ac re ) , and C--19 (13,000 p lan t s /ac re ) .

Relationships existing among the level of net-energy intake, grain to forage ratio, and level of milk production for cows in North Carolina Dairy Herd Improvement Associa- tion herds. F. N. KNOT~, North Carolina State College, Raleigh.

Feed and production data for the first four months of lactat ion for 4,424 selected cows of three breeds were analyzed. Al l cows had calving dates during the six consecutive months

from September through Februa ry and each lactat ion was at least 240 days.

The level of energy intake affected produc- tion in a l inear fashion within the range o£ these data. Each addit ional therm per day resulted in an average production increase of 1.6 lb of F.C.M. per day. Product ion response tended to diminish at the higher intake levels.

These data indicate that 41% of the cows were fed less than Morrison's s tandards for net energy during the first four months of lactation. Twenty-nine per cent was fed 10% or more above these standards. F i f ty-e ight per cent of the cows producing 45 lb or more of F.C.M. daily were underfed.

The data fur ther indicate that grain feed- ing' should be adjusted upward for high-pro- ducing cows and downward for low producers a t the reported level of energy intake from forages.

Changes in feed calculations in the machine- computed Dairy Herd Improvement Associa- tion program. M. E. SENGER, North Carolina State College, Raleigh.

There are indications that the present feed- ing standards used in the program for machine- calculating of D H I A records are too low, especially for high-producing cows. I t is also observed that the net-energy value (74%) used for concentrate mixtures is too higb for the average grain mixture in the southern states. Because of these factors the com- puted pounds of grain indicated to feed each cow on the monthly D H I A repor t is too low to maintain maximum production. This is especially true in the early par t of the lacta- tion.

G. E. Hawkins and R. Sam Jones, Jr., Au- buru University, have developed a formula that increases the energy requirements to produce a pound of milk as milk production increases. The increase in energy is reflected in the amount of grain indicated to feed on the computed D H I A report.

Studies made of 416 commercial dairy feeds and 241 grain samples in North Carolina showed the average est imated net energy to be sl ightly less than 70%, based on crude fiber determination and an assumed 86% dry mat- ter.

Zinc content of some feed ingredients and materials. W. J. MILLER AND J. K. MILLER, Universi ty of Georgia, Athens.

In conducting zinc research with cattle, the scarci ty of reliable data on the zinc content of various feed ingredients and related mate- r ia ls is a serious handicap. The average zinc contents in par t s per million as deterufined by a dithizone procedure of several materials were: [nmnber of samples given in ( ) when more than one] : whole fresh milk, 3.9 (range 2.8-4.8) (14); dried beet pulp, 8.9 (range 7.4-11.0) (7); Coastal Bermudagrass hay,

ASSOCiATiON AFFAIRS 307

grown in Piedmont, 27 (range 23-32) (4) ; coastal hay, grown in Coastal Plain, 16 (range 12-22) (19); dried citrus pulp, 8.9 (4) ; soy- bean meal, 62 (2) ; yellow corn grain, 24 (2) ; soybran flakes, 67; urea (42% feed mixture) , 6.2; isolated soybean protein, 39 (2) ; glucose monohydrate, 1.0 (2) ; egg albumen, 2.5; lard, 1.1; nonfat dry milk, 41; defluorinated rock phosphate, 38; marble dust, (Tare, Georgia) 3.5; pine shavings, 6.8 (2) ; water, tap, galva- nized pipe, 0.65; water, tap, no galvanized pipe, 0.04 (3) ; water, galvanized pipe, singly distilled, 0.10 (2) ; concrete, 5.5; anhydrous sodium sulfate, 0; sesame oil meal, 104; lac- talbumin, edible, 13; casein, food and pharma- ceutical grade, 26; calcium easeinate, food grade, 57; and dicalcium phosphate, food grade, anhydrous, 1.8.

Effect of grain feeding on rate of passage of food through the digestive tract of the cow. O. H. HORTON ¢~ AND J. W. BELL, Universi ty of Arkansas, Fayet tevi l le .

Ten lacta t ing cows were used in a two- t reatment Latin-square change-over design in which digestion tr ials were conducted. During one of these t r ials 30 g of dyed hay was fed at the beginning of the collection period. The dietary regime for Treatment A was concen- t ra tes fed free-choice and a l fa l fa hay fed at a ra te of 0.8 lb per 100 lb of body weight ; for Treatment B, 1 ]b of concentrate per 2 Ib of milk with a l fa l fa hay free-choice.

F i r s t appearance of stained hay in the feces was not sooner than 13 hr, but within 17.5 hr a f te r feeding for all cows. The mean time when stained part icles was first observed was 13 hr for the cows on Treatment B as com- pared to 15 hr for Treatment A. However, the peak excretion rate was higher and 2 hr sooner for cows on the Treatment A. The cows on Treatment A reached a peak excre- tion rate at 22 hr, and those on B at 24.1 hr af ter feeding. Excretion of stained par t ic les varied considerably in both groups up to approximately 68 hr, at which time the num- ber observed leveled off. Low concentrations continued for 140 hr when counts were dis- continued. Heavy grain feeding increases the rate of passage of foodstuff.

Effect of supplemental feeding of cows on pasture on milk production and composition. J. T. HUBER, G. C. GRAF, AND R. W. ENGEL, Virginia Agr icul tura l Experiment Station, Blacksburg.

Four groups of lactat ing Holstein cows (six per group) on permanent bluegrass pas ture were fed an experimental ra t ion for 2 hr be- fore each milking. The rat ions were: I. Ground-shelled corn; II . Ground-shelled corn plus corn silage (28.0% dry ma t t e r ) ; I I I . Ground-shelled corn (1 lb per 6 lb milk) plus corn silage; and IV. Corn silage. Unless otherwise specified, feeds were offered ad

libitum. Addit ional ly, all cows were fed 2 lb soybean oil meal per day. Treatments were for 86 days and included a 2-wk period of adjus tment a t the beginning of the experiment. Milk was sampled every ten days and ana- lyzed for composition.

Average daily intakes of ground-shelled corn for Groups I to I I I , respectively, were: 24.0, 22.8, and 6.9 lb; whereas, corn silage consumed by Groups I I to IV, respectively, amounted to 24.1, 46.1, and 54.1 lb. Pounds of milk produced per day for the respective groups were: 36.6, 39.5, 38.0, and 35.0. F a t content of milk for the respective t reatments was: 2.5, 3.2, 3.5, and 3.6%. Solids-not-fat for the t reatments were: 9.2; 8.9; 8.7; and 8.4%, respectively. Per cent protein for the respective groups was: 3.45, 3.31, 3.19, and 2.97. Lactose-mineral was sl ightly higher for animals fed l iberal amounts of grain.

Effects on milk production of supplementary bulky concentrate feeding. J. M. WING AND C. J. WILCOx, F lo r ida Agr icul tura l Experi- ment Station, Gainesville.

During 1959-60 and 1960-61, 90 lactat ions of 200-day durat ion were completed by Hol- stein, Jersey, and Guernsey cows assigned to one of three t reatment groups: (A) concen- t ra tes fed individual ly according to recom- mended s tandards ; (B) Treatment A plus in- dividually fed bulky concentrates; and (C) Treatment A plus group-fed bulky concen- trates. The bulky concentrate mixture con- sisted of 50.0% ground snapped corn, 33.3% citrus pulp, and 16.7% brewers grains, being rela t ively inexpensive, high in energy, low in digestible protein, and very palatable. Al l animals received the same good to excellent qual i ty forage ad libitum. Dai ly consumption rates for concentrates averaged: (A) 8.44 and 0 lb, (B) 8.51 and 4.91 lb, and (C) 7.96 and 4.91 lb. Forage intake was not measured. Average changes in body weight during" the comparison period were +6 , +22, and + 1 4 lb, respectively. There were no significant differ- ences among groups in average daily produc- tion of 4% FCM, or % SNF, protein, chlo- ride, or t i t ra table acidity. Averages were, (A) 33.3 lb, 9.48, 3.41, 0.140, and 0.145%, (B) 34.2 lb, 9.41, 3.42, 0.140, and 0.145%, and (C) 32.8 lb, 9.49, 3.48, 0.138, and 0.141%.

Simple vs. complex grain mixtures for lac- tating cows. W. R. MURLE:r., Agricul tura l Ex- per iment Station, North Carolina State Col- lege, Raleigh.

A long-time t r ia l comparing a simple three- ingredient grain mixture with one containing nine ingredients was conducted with high-pro- ducing dai ry cows. For ty-e ight animals were pai red and randomly assigned to these sep- arate grain rations, beginning at 6 wk before calving and fed through the lactat ion and subsequent dry period to next calving. All

368 J O U R N A L OF D A I R Y S C I E N C E

cows received regular herd roughage feeding and care. The roughage consisted of heavy feeding of corn silage, l ight feeding of al- fa l fa-grass hay, and limited pasture during pas ture season. No stat is t ical differences were shown between average milk production (305- day, ME, FCM) of 11911 and 12084 for the simple and complex rat ion groups, respec- tively, nor for body weight changes of H-9 and --125 lb. Grain intake during the 305-day lactat ion averaged 11.4 lb per day for both groups. The conception rates (times bred be- fore conception) were 2.1 and 3.0, with three and six cows fai l ing to conceive before the end of the 305-day lactat ion for the simple and conlplex groups, respectively. No ab- normali t ies at calving were noted and result- ing offspring were apparent ly normal.

Effect of feeding thyroxine on secretion 1131 in milk. J. K. MILLER, ~ E. W. SWANSON, AND R. G. CRAGLE z UT-AEC Agricultural Re- search Laboratory, Oak Ridge, and Universi ty of Tennessee, Knoxville.

Eight comparisons were made of lactat ing cows fed L-thyroxine, pai red ei ther with their identical twins or with their own performance in adjacent periods when no thyroxine was fed. L-thyroxine was fed at 80 mg per cow daily from 2 wk before dosing with 2 me N a F l through a seven-day collection period. An 11.1% increase in milk production over p re t rea tment yield was observed during col- lection periods. In comparing thyroxine fed vs. control cows, average values were: milk production, 17.3 vs. 14.9 lb; biological half- time of I TM, 41 vs. 63 hr ; excretion of dose via milk, 5.6 vs. 4.0%; urine, 57.5 vs. 38.8%; and feces, 30.7 vs. 23.7%. The differences between thyroxine and control values were significant (P < .01). Concentration of I ~"~ in the milk was not affected by treatment, and near ly all of the increased excretion in milk was related to greater production. Eighty per cent of the radioact iv i ty in plasms from control cows was protein-bound by the seventh day af te r dos- ing, compared with 17% from those fed thy- roxine. Thyroxine blocked uptake of I TM by the ttlyroid, leaving more available for excre- tion in urine and feces.

Effect of heat stress on growth, feed con- sumption, and digestibil ity in Holstein calves from birth to 90 days of age. P. F. RANDEL ANI) L. L. Rvsoi~i~, Louisiana Agricul tura l Ex- per iment Station, Baton Rouge.

Two groups of newborn Holstein calves, each consisting of five females and four niales, were maintained either under controlled con- ditions of a i r temperature cycling from 75 to 95 F and constant vapor pressure at 20 mm Hg (experimental group) or under ambient winter climatic conditions (control group). Feeding and nianagement practices were the same for both groups. The calves received

whole milk until 3 wk of age, then skimmilk until 8 wk of age. High-qual i ty a l fa l fa hay and a grain mixture were fed ad libitum. The results were analyzed as three separate experimental periods, i.e., bir th to 30 days, 31 days to 60 days, and 61 days to 90 days. Individual digest ibi l i ty tr ials with five-day feces collection periods were conducted on the 14 oldest calves during Period I I I . The data from Period I I I are complete on only ten of the 18 calves, since the psychrometric chamber was not available to enable completions of Period I I I for the last eight calves.

The average daily body weight gains nmde by the experimental-group and by the control- group calves in Periods I through I I I were: 0.56 and 0.74, 0.74 and 1.19, and 0.56 and 1.50 lb, respectively. These differences between groups were nonsignificant in Period I, but highly significant (P < 0.01) in Periods I I and I I I . The corresponding daily grain dry mat ter consumption figures for the three periods were: 0.19 and 0.48, 0.43 and 1.30, and 1.70 and 3.36 lb, respectively. These dif- ferences were significant (P < 0.05) in Per iod I and highly significant (P < 0.01) in Periods I I and I I I . The corresponding figures for daily hay dry mat ter consumption for the periods were: 0.03 and 0.07, 0.24 and 0.54, and 0.73 and 1.18 lb, respectively. The difference be- tween groups was significant (P < 0.05) only in Per iod II . The average apparent digesti- bi l i ty coefficients determined in experimental- group and in control-group calves were: 66.1 and 69.4 for dry matter , 68.7 and 72.1 for crude protein, 63.0 and 67.5 for gross energy, and 66.6 and 70.4 for total nutrients (TDN system), respectively. None of the differences between groups in digest ibi l i ty coefficients was significant.

Effect of certain management practices on milk production in Georgia. H. W. ~cKINNEY AND O. T. FOSGATE, Universi ty of Georgia, Athens.

Dairy Herd Improvement Association (DHIA) production records from 305 herds total l ing 19,636 cows were converted to 4% FCI-VI for analysis. Data on herd size and management practices were collected from D H I A herd books, supervisors, and monthly visits to the farms. Discrete variables studied were management of breeding program; con- eentrate feeding program; type milking facil- i t ies; and effect of pipeline niilking. Par t i a l regressions were computed for per cent man- agement by fani i ly; per cent of cows sired art if icially; months enrolled on DHIA; num- ber of milking machines used; herd size; total men in milking operat ion; and average total milking time.

A multiple correlat ion coefficient (R ~) of 30.7 was computed for the variables studied. Yearly increases per cow of 1,150 Ib FCIK

ASSOCIATION AFFAIRS 369

were obtained when the breeding program was controlled by the owner vs. leaving to hired help; 902 lb FCM increase for measur- ing concentrates vs. est imating or not feeding according to production; 548 lb FCM increase for milking in a parlor vs. stanchion barn, and the part ial regression of 7.5 lb FCM per increase in per cent of cows sired artificially were all highly significant (P ~ .01). Re- gressipn of number of machines used on milk production was significant (P < .05). Differ- ences in variation of the other variables stud- ied were not significant.

Crossbred dairy cattle compared with their purebred contemporaries for milk and fat pro- duction. G. W. BRANDT, * AI~D C. C. BRANI~ON, South Carolina Agricultural Experiment Sta- tion, Clemson; ~ D W. R. HARVEY, Biomet- rical Services, A~D R. E'. McDowELL, Dairy Cattle Research Branch, USDA, Beltsville, Maryland.

First- lactat ion records were used in com- paring 15 crossbred groups of different com- binations of the Guernsey, Holstein, and Brown Swiss breeds to their purebred con- temporaries for milk, fat, per cent fat, and FCM. Six groups were Guernsey-Holstein crosses with up to 75% of either of the two breeds. Nine groups had up to 50% Brown Swiss inheritance in addition to Holstein or Guernsey, or both breeds. Deviations of a crossbred's record from averages of contempo- raries were weighted for number of contem- poraries and per cent inheritance from each breed. Deviations were analyzed by the least- squares method and tests of significance made by analysis of variance and co-variance. None of the trai ts differed significantly among the 15 crossbred groups. Yariabil i ty was con- siderable in both crossbred and purebred rec- ords, and much of it was associated with length of record, as variances within sire for milk, fat, and FCM were greatly reduced by adjusting for length of record, and age of the crossbred at calving. Sire differences were significant for milk On adjusted records. The average deviation for each trai t within each group was tested for positive or negative heterosis. Only four of the 60 tests indicated any real difference.

Rumen parakeratosis in dairy cattle. L. J. Bus]I, B. HARRIS, JR., J. D. FRIElqD, AlqD S. D. MUSGRaVE, ~ Oklahoma State University, Still- water.

Three trials involving 12-14 calves each were conducted to determine the effect of different rations on the incidence of ruminal parakeratosis and on certain biochemical con- ditions in the rumen. All calves were raised on a limited milk-calf starter program and started on experiment at three months of age. volat i le fa t ty acid and pH dete~mlinations were made on the rumen fluid taken at 4- and

8-hr intervals after feeding during the eighth week on experiment. In Trial I, the calves were housed in pens with expanded metal floors with no bedding. A ration having a 1:1 ratio of concentrates to roughage was fed consist- ing of baled, wafered, and pelleted hay for the three respective treatment groups. Ex- tensive ruminal parakeratosis was observed in calves fed pelleted hay, whereas calves fed wafered or long hay had only slight to mod- erate degrees of parakeratosis. In Trial II , involving two groups of seven calves each, wood shavings were used for bedding and a 4:1 (concentrate to roughage) ration was fed, with the hay being baled and pelleted for the two respective groups. No ruminal para- keratosis was observed in either of these two groups. In both Trials I and II , the pH of the rmnen fluid was lower in calves fed pel- leted hay than in those fed hay in other forms. Trial I I I was similar to Trial I I , except that the calves were maintained under dry-lot feed- ing conditions with no bedding.

Relationships between udder and teat meas- urements and milk flow. J. M. RAKES AND G. L. FORD, e University of Arkansas, Fayette- ville.

Rate of milk flow was recorded A~ and P~ on 119 Holstein, 80 Jersey, 16 Brown Swiss, and 22 GueI~sey cows. Milk flow rate was determined by recording pounds of milk ejected each 15 sec. Udder area between teats was calculated before and after milking to meas- ure expansion of the udder. Width and length of teats were measured before and after milk- ing. Teats were also classified as to type of orifice.

Correlations were calculated between udder measurements and milk flow characteristics. Highest correlations were obtained between pounds milk produced vs. : maximum and aver- age rate of milk flow per minute, 0.49 and 0.40, respectively. Expansion coefficients, cal- culated as the per cent of decrease in udder area, were variable, being at tr ibuted to indi- vidual cow variation. A correlation of 0.25 was found between expansion coefficient and pounds of milk produced. Correlation between expanded udder area and daily milk produc- tion was 0.39.

Data classified on the basis of 19 sire groups indicated that type of teat orifice might be influenced by sire. Daughter-dam comparisons were too limited to form any conclusions on the heritabili ty of this characteristic.

Gonadotropic complex in repeat breeder dairy cattle based on clinical treatment with Gonadogen. N. PATI, The Agricultural and Technical College of North Carolina, Greens- boro.

Fif teen repeat breeder Holstein cows were treated with Gonadogen. They were bred at least ten times before the treatment. The

370 J O U R N A L OF D A I R Y SCIENCE

animals were free from the infections. All t rea ted animals conceived when they were bred the second time af te r a single dose of Gonadogen. This indicates tha t the t rea tment of repeat breeders depends to a large extent on the level of fol l icular s t imulat ing and leutinizing hormone of the anterior p i t u i t a ry before the estrus. I f the repeat breeding con- dit ion is due to the unbalance of gonadotropic hormone with high F .S . t t . and low L.H., then the animals should respond to the Gonadogen treatment , provided they do not have any secondary infections or other complication. Therefore, i t is logical to assume tha t fa i lure of the repeat breeders to respond against t rea tment with gonadotrophie hormone could be due to the selection and use of ei ther a gonatotrophin which has high F.S.I t . and low L.H. or a gonadotrophin which has low F.S . t t . and high L.tI. value.

Livabfl i ty of bovine spermatozoa when di- luted with different semen extenders. 0. T. FOSGATE hlqD I. M. KHAn, Univers i ty of Georgia, Athens.

Fol lowing a 4-wk pre l iminary adjus tment period, six weekly semen ejaculates were col- lected from each of three bulls. Ejacula tes were spli t into six fract ions and extended to 20 millions of spermatozoa per milli l i ter. Ex- tended semen samples were then spli t and stored at 5 C and at 25 C. Basic extenders used were egg yolk-c i t ra te (EYC); reconsti- tuted but termilk (RB) ; Arkansas no. 2; I l l i - nois Variable Temperature (IVT); and Cor- nell Universi ty extenders CUE and CU-16. Extenders were adjusted to p t I 6.5 by passing CO.. gas through them.

Sanlples were assessed for mot i l i ty and l ivabi l i ty microscopically, with the slides warmed to 38 C, using a stage incubator. IVT and Arkansas no. 2 extenders were signifi- cant ly bet ter at maintaining l ivabi l i ty and moti l i ty as compared to the other four (P <

.01), but were not significantly different from each other. EYC and RB were not signifi- cantly different from each other, but were significantly bet ter at maintaining l ivabi l i ty than the CUE or CU-16 extenders (P < .05). Interact ions between bull and extender and extender and storage temperature were ~]eg- ligible. Decline in percentage of motile cells showed a l inear relat ionship with storage time for all extenders. None of the extenders main- tained a high degree of l ivabil i ty ( > 50% motile cells) for more than four days of stor- age.

Forage test ing programs. RICHARD E. BURLE- SO~, U. S. Department of Agriculture, Wash- ington 25, D. C.

A national survey, with 45 states repol¢- ing, revealed that 22 states were conducting a forage testing program involving chemical analysis. Several other states were using other methods of evaluation, such as date of cutting and visual estimation. Southern states repor t ing organized programs were Alabama, Arkansas , Georgia, Kentucky, North Caro- lina, Oklahoma, South Carolina, and Virginia.

All of the Southern states with programs were offering chemical analysis for hay and silage, and North Carolina also includes gra in samples. Par t ic ipa t ion as a whole has been rather low. Three of the Southern states are using commercial laboratories, three use the State Depar tment of Agricul ture laboratories, and two states are using the laboratories a t the University. Charges per sample varies from no charge to a high of $7.50. Most of the state programs assist farmers in using the information through a feeding program service or feeding guides.

Some of the problems listed were low par- t icipation, obtaining representat ive samples, variations, feeding recommendations and eval- uation of program.