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Staphylococcal enterotoxin C (SEC), a superantigen, is the most frequently expressed enterotoxin by bovine strains of Staphylococcus aureus causing mastitis. To examine the possible impact of SEC on the immune response of the bovine mammary gland, we monitored changes in lymphocyte subpopulations in mammary glands of four lactating cows after intramammary instillation of S. aureus strain Rn4220 transformed with a plasmid containing a gene coding for SEC1. Four other lactating cows received the same strain transformed with the plasmid without the SEC1 gene (positive control), and four cows were untreated (negative control). Mammary quarter milk samples for somatic cell count (SCC) analysis and determination of N-acetyl-beta-D-glucosimindase (NAGase) activity levels were collected daily for 21 d postinstillation. Flow cytometry utilizing three-color analysis was used to phenotype lymphocyte subpopulations isolated from milk samples collected on d 0, 4, 7, 11, 14, 18, and 21 postinstillation from all the cows. Milk from mammary gland halves (positive control and experimental) or all mammary quarters (negative control) was collected for flow cytometric analysis. Increased NAGase activity, SCC, and isolated S. aureus demonstrated that infection was established in mammary quarters intrammarily instilled with bacteria. There were no significant differences (P0.05) in the proportions of BoCD4 helper T lymphocytes or BoCD8 cytotoxic T lymphocytes between the two infected treatment groups. There was a significant day x treatment difference of the proportion of a gammadelta T cell subpopulation that did not express BoCD2, but did express the ACT2 activation molecule and a significant treatment difference of a gammadelta T cell subpopulation that expressed BoCD2, but not the ACT2 activation molecule (P0.05). Results do not support the hypothesis that the presence of the gene for SEC1 alters the mammary BoCD4 or BoCD8 T lymphocyte response to infection.

Televideoconferences utilize satellite broadcast technology and telephone lines to present interactive educational programs. Washington State University, in cooperation with University of Idaho, Utah State University, and Oregon State University, has produced a series of televised interactive dairy programs since fall 1988. Advantages of satellite programs over traditional efforts include the ability to reach remote clientele and to present a single program to an audience dispersed over a broad geographical area. Telephones provide direct access to speakers, thereby exposing large audiences to expertise that may not usually be available. A valuable by-product is a videotape record of the program, which further increases availability of educational programs through secondary viewing. Finally, cost of producing the program is substantially reduced on a per registrant basis over a live conference. Disadvantages include diminished and limited audience-speaker interaction, limited availability of satellite transmission receiving facilities, increased planning and program preparation efforts compared with traditional programs by increased use of high level technology, and multiple locations of remote viewing audiences. Moreover, although cost per participant is reduced, costs are substantial, and funding is difficult to raise through user fees. Motivating individuals to view teleconference programs live is a major challenge. Based on registration numbers from 1988 to 1990 in Washington, viewership declines once the novelty wears off, Potential for this program presentation method is great, and further experience is necessary to refine productions to benefit clientele further and to make maximal use of the technology.

Household food consumption survey data was used in an analysis of the significance and level of milk component values perceived by consumers at the retail level. The research was based on the new approach based on hedonic assessment of product characteristics for demand analysis. Dairy products analyzed included beverage milk products and three types of cheeses. The estimated nonlinear regression function explaining dairy product retail prices indicated that the protein, fat, and calcium components of raw milk were perceived by consumers as having significant value in the marketplace. Regarding relative value, on average, the protein component was perceived to be 28% more valuable than the fat component per point. Decomposing the $9.45 per hundredweight price of raw milk given average milk component levels existing during the time the survey data was collected, $3.76 was attributable to the protein component, $3.29 represented fat value, and $2.40 was assigned as calcium value.

This trial was to determine the effect of dietary rapeseed screenings on milk production, milk composition, and feed intake of lactating dairy cows. Pelleted rapeseed screenings were fed at 0, 7, and 14% of diet DM. Assignment of 36 multiparous Holstein cows was based upon parity and previous lactation performance. The experimental period was from parturition through wk 16 of lactation. The control ration had 3.1% ether extract, whereas the ration with 14% rapeseed screenings had 5.4% ether extract. The rapeseed screenings contained 52.2% of C18:1 and 24.2% of C18:2 as percentage of total fatty acids. There were no significant effects of dietary treatment on milk yield or feed intake. There were significant increases in milk fatty acids C18:1 and C18:2 for cows consuming the diets with rapeseed screenings. Treatment did not significantly affect milk protein percentage as measured by Kjeldahl N or by the infrared method. Increased unsaturated fatty acids in the milk of cows fed rapeseed screenings had no apparent effect on infrared fat analysis. There was no interaction of treatment and milk fat analysis method (infrared versus Babcock). Dietary treatment did not affect blood serum nonesterified fatty acid concentrations over the 16-wk period. In conclusion, rapeseed screenings, fed at levels up to 14% of the diet, did not affect milk yield, milk protein, or milk fat percentage but did change milk fatty acid composition.

A split-plot design with repeated measures was used to test the relationship between visual teat skin condition score, the degree of transepidermal water loss from the skin, and the colonization by Staphylococcus aureus on experimentally chapped and inoculated teats of 20 lactating Holstein cows. Visual teat skin chapping score and the number of S. aureus colonies obtained from a teat skin swab were correlated (r = 0.53). Transepidermal water loss and S. aureus count were not correlated (r = 0.02). Results indicated that visual teat skin evaluation is superior to measurements of transepidermal water loss in the prediction of the susceptibility of teat skin to colonization by S. aureus.

An incomplete block split-plot design with repeated measures was used to test the effects of eight combinations of premilking and postmilking teat disinfectants on teat skin and teat end condition over a 6-wk period. These combinations included iodine, sodium chlorite, lactic acid, and orthophosphoric acid. Visual assessments of teat skin and teat ends were made on the teats of 101 cows. Teat skin thickness, teat end thickness, and transepidermal water loss were assessed for the teats of 50 cows. The interaction of predip and postdip had no effect on teat condition. Postdip had a significant effect on transepidermal water loss, visual teat skin condition, and visual teat end condition. The 1% iodine postdip was associated with the poorest teat skin condition.

Effects of genetic merit on energy intake, milk yield, fat and protein percentages, BW, BW change, plasma concentration of bST, and plasma concentration of urea N were determined for 139 heifers. Heifers, daughters of bulls of high genetic merit (average +408 kg of PTA for milk) or of average genetic merit (average -153 kg of PTA for milk), were allotted to either a high or low energy diet. Heifers of high genetic merit yielded 8.1% more milk and had 7.7% higher bST concentration than did heifers of average genetic merit, which were 3% heavier than heifers of high genetic merit. There was no significant effect of genetic merit group on energy intake, plasma concentration of urea N, or percentages of fat and protein. Heifers fed the high energy diet consumed 35.1% more energy, yielded 11.8% more milk with a lower fat percentage, and weighed 3% more than did heifers fed the low energy diet. The high energy diet depressed bST concentration by 13.3% and plasma concentration of urea N by 14.2% compared with concentrations for heifers fed the low energy diet. Correlations among bST, BW, and energy intake were negative and significant. Correlations of bST concentration with milk yield, fat percentage, and protein percentage were not significant. Body weight, BW change, milk yield, and energy intake were negatively correlated with plasma concentration of urea N.

The objective of the study was to establish and compare equations that would estimate the body fat content of lactating dairy cows from different indirect techniques. The techniques used were body condition scoring, dilution of D 2 O in body water, and determination of mean fat cell size diameter of the subcutaneous, abdominal, and perirenal depots. Each technique was validated against direct determination of body fat content of the same lactating cows. To apply equations to high producing, lactating dairy cows, cows were from a herd producing more than 9500kg of FCM/305 d, were lactating, and were in less than average body condition. Eight days prior to slaughter, a single injection of D 2 O was injected into the jugular vein, and body dilution was followed for 4 d. Cows were scored for body condition on the day of injection and weighed daily for the 4 d prior to slaughter. Samples of subcutaneous, perirenal, and omental adipose depots were taken, and adipocyte size and number were determined. Body fat was not predicted well by D 2 O space alone, but inclusion of BW did improve the prediction of body fat from this variable. The best equations were derived from use of BW with body condition score or subcutaneous fat cell diameter: observed body fat=−122.1 + .21 × BW + 36.0 × body condition score, and −195.6 + .290 × BW + .927 × subcutaneous fat cell diameter; standard errors of the estimate were 4.6 and 5.5kg, respectively. Equations using diameters of abdominal and perirenal fat cells gave similar relationships. Equations using all four predictors (live BW, fat cell diameter, condition score, and D 2 O space) were only slightly improved over these equations. Thus, use of body condition score, adipocyte diameter, and BW in laboratory and field conditions may help in the study and management of the use of body fat in lactating dairy cows.

Practical relationships were determined between milk production, health, and reproduction with the amount and use of body fat in high producing lactating Holstein dairy cattle. Approximately 350 cows and heifers > 15 mo of age in a high producing herd were assigned body condition scores at monthly intervals for 24 mo. Production of 305-d FCM averaged 9541 kg (range 8826 to 10,818 kg). Body condition score at each of four calvings at 30, 60, 90, 120, and 305 DIM in each parity and loss in score in each lactation were summarized. Multiple regression related scores to milk and milk fat production, reproduction, and disease variables within and among lactations. No difference in score occurred at calving or at dry-off among parities. The range of body condition scores was less than is commonly reported; however, loss of condition increased with increasing parity from .3 in first lactation to .9 body condition score units in lactations > or = 4. The body condition score varied quadratically with DIM but, at a given DIM, was not related to the daily milk production on that DIM. Parity had a stronger relationship with milk and milk fat production than did body condition score. However, within lactation, body condition score at calving and the loss of score were related quadratically to milk production. No significant relationships of body condition score to the incidences of pyometra, metritis, retained placenta, cystic ovarian disease, AI per conception, days to first AI, or dystocia existed in this herd.

Forty Holstein cows were assigned among four dietary treatments that resulted in dietary calcium and phosphorus: 1) 1.0%, .31%; 2) 1.0%, .54%; 3) 1.8%, .30%; and 4) 1.7%, .54%. Calcium was supplemented as ground limestone and phosphorus as sodium tripolyphosphate. Treatment diets were fed from parturition until 10 mo postpartum. Cows fed diets low in phosphorus had lower milk yields, feed intakes, and poorer efficiencies of milk production. Inorganic phosphorus in blood plasma was reduced by low phosphorus intake. Overall, calcium of the diet did not affect milk production. However, there was a significant calcium-phosphorus interaction with increased milk production and greater feed intake when calcium was added to low phosphorus diets but not to diets containing excess phosphorus. Added calcium did not affect inorganic phosphorus, calcium, or magnesium of blood plasma. Fecal pH was increased and percent starch in the feces decreased with added dietary limestone. Efficiency of milk production was not improved by added limestone. Maximum milk yields and performance cannot be obtained with .3% dietary phosphorus.

Diurnal changes in percents of inorganic phosphorus in plasma were measured in three Holstein cows fitted with indwelling jugular catheters. Blood was sampled 34 times over 48 h. Changes of inorganic phosphorus of blood plasma appeared to be related to patterns of feed consumption. In a second experiment, effects of diet, season of calving, stage of lactation, lactation number, and milk yield on inorganic phosphorus of plasma and milk were measured with 40 Holstein cows. Dietary treatments were 1.0% calcium, .31% phosphorus; 1.0% and .54%; 1.8% and .30%; 1.7% and .54%. Blood and milk samples were taken at wk 6 postpartum and every 5th wk thereafter. Inorganic phosphorus in plasma and milk was higher for cows in first lactation than multiparous cows. Cows which calved in November to December had the highest inorganic phosphorus in plasma but the lowest in milk. Month of year affected inorganic phosphorus in milk but not in plasma. Inorganic phosphorus in plasma increased as milk yields decreased and as inorganic phosphorus in milk decreased. Dietary phosphorus affected inorganic phosphorus in plasma but not in milk. The correlation between inorganic phosphorus in milk and plasma was -.15. These data indicate the limitations of using inorganic phosphorus in plasma or milk as sole or primary means of determining nutritional phosphorus status of lactating cows.

Factors affecting the amount of milk sold and its fat and protein content were evaluated. Data in the analysis were monthly milk sold and its average fat and protein content from 359 producers for 1975, 1976, and 1977 in the Midwest. Monthly fluctuations in protein content were similar but less pronounced and consistent than fluctuations in fat content. The regression of monthly herd average protein content on fat content was about .4. The effect of three pricing systems on the average price received by producers for their milk was evaluated. The pricing systems included the present system with only a fat differential, a system with both a fat and protein differential (fat-protein system), and a system with a fat differential and protein differential utilizing an expected protein content estimated from the fat content (Froker-Hardin system). Total payout was the same for the three pricing systems. For each of the assumed protein differentials, the present pricing system overcompensated producers of low fat milk and undercompensated producers of high fat milk. The fat-protein and the Froker-Hardin system resulted in about the same average price for milk of different fat levels. However, significant differences in payment occurred between the Froker-Hardin and fat-protein system for milk from different producers containing the same fat content because of differences in protein content.

Systems analysis was used to study costs and returns of breeding dairy cows artificially or naturally. In the analysis were costs of semen, detection of estrus for artificial insemination, days open, and maintaining bulls. Also included were genetic abilities of sires, discount rates on expected returns, and probability of a female offspring reaching lactation. Transmission of genetic superiority of sires used artificially over sires used naturally to both daughter and grand-daughter was considered. Daughters of sires used artificially were superior to daughters of natural service sires by 227, 454, or 682kg (mature equivalent) milk. Breeding was started 60 days into lactation and continued for 15 cycles (21 days each) or until 90% of the cows would be expected to have conceived. Conception rate from artificial service was decreased by 5% of its rate for each subsequent breeding. For comparing artificial insemination and natural service, an initial conception rate for artificial insemination of 50%, cost of keeping a bull of $15 per cow per yr, semen cost of $8 per unit, costs for detection of estrus of $10 per cow per yr, discount rate of 10%, a 40% chance of obtaining a lactating heifer replacement per conception, a cost of an additional day open of $1.50, and income over feed costs of $.099 per kg were applied. Calving interval was 365 days for breeding by natural service. Each increase in genetic superiority of bulls used artificially over natural service bulls of 227 kg meant that the calving interval from artificial insemination could be 10 days longer with the same expected returns. Other factors in the analysis had less effect on the comparison of artificial insemination with natural service than the genetic abilities of sires. Investment in herd health (reproductive) programs to increase breeding efficiency appeared economically sound.

The objective was to determine the relationship between thawing time and post-thaw temperature when the final temperature of the semen was brought to 40 C. One ejaculate from each of 12 dairy bulls was packaged in .5-ml French straws. Semen in five straws from each ejaculate was thawed in a 35 c water bath for 12 s or 1 min. The straws were then immediately placed in water baths at 0, 10 or 20 C for 1 min and then transferred to a water bath at 40 C for 1 min. Control treatments were thawed at (1) 35 C for 1 min, plunged into a 35 C water bath for 1 min and transferred to a final water bath at 40 C for 1 min, and (2) thawed at 40 C for 1 min, plunged into 40 C water bath for 1 min and transferred to a final water bath at 40 C for 1 min. Semen was incubated at 40 C and evaluated at 0, 4 and 8 h of incubation for percentage of motile spermatozoa (%MOT) and percentage of spermatozoa with intact acrosomes (PIA). Semen thawed at 35 C for 12 s and held at 0 C before being warmed to 40 C sustained immediate acrosomal damage (P less than .05) due to a delay in complete thawing of the semen. Semen thawed at 35 C for 1 min, held at 0 C and then warmed to 40 C also sustained immediate acrosomal damage which was due to cold shock. Cold shock damage was greater than damage due to a delay in complete thawing, therefore, precautions should be taken to prevent post-thawing cold shock. The 10 C post-thaw treatment resulted in spermatozoal damage with both thawing times, however, the effects were latent since damage was not observed until the 4- and 8-h evaluations. The 20 C post-thaw treatment did not decrease (P greater than .05) % MOT or PIA with either thawing time.

The economic value of solids components of milk should be a function of net returns from products in which the milk solids are used. An empirical procedure is illustrated to estimate the value of fat and protein in milk used to manufacture selected dairy products. Manufacturing costs were evaluated and divided into those that remain constant for a volume of milk regardless of solids content and those costs that change with the solids content of milk. Values of a .1% increase in the protein content in 100 kg of milk used to manufacture hard cheese, nonfat dry milk, and cottage cheese were $.300, $.140, and $.446. Values of .1% increase in fat in 100 kg of milk used to manufacture hard cheese and butter were $.364 and $.240. Values derived in this manner can be incorporated into multiple-component pricing plans by weighting each value by the proportion of the milk supply used for that product.

Relationships between calf birth weight and the dam's subsequent 200- and 305-day yields of milk, fat, and total solids were investigated in a total of 1471 calvings from two experimental stations and 28 yr. Independent variables included in least-squares analyses were year of calving, sex of calf, and linear and quadratic effects of age of cow and calf birth weight. Sex of calf had no significant effect on any yield variable. Effects of age of cow and year of calving were significant and positive on all measures of yield. The relationship between calf birth weight and each yield measure was linear and positive for calf birth weights between 23 and 50 kg. Expected differences in 200-day yields of milk, fat, and solids were 15.2, 11.0, and 18.8% higher for 50 kg calf birth weight as compared to 30 kg calf birth weight. Corresponding differences in 305-day milk, fat, and solids were 9.4, 4.5, and 11.8%. Thus, yields of milk, fat, and solids in Holsteins increase with increasing calf birth weight.

Considerable forethought must be given to breeding programs in dairy cattle because of the long generation interval. Protein content of milk is of increasing importance because of shifts of consumption patterns and changes of the relative cost of energy. Tools are available to alter genetically the composition of the milk from our dairy population. However, the current milk pricing system provides little economic incentive to breeders to increase the protein content of milk. Changing the milk pricing system to reflect the value of components other than fat should stimulate producers to evaluate the milk of more cows for protein content as part of the Dairy Herd Improvement program and to change milk composition to reflect milk utilization more accurately.

Blood and milk were sampled and quarter California Mastitis Test scores were taken during four 2-wk periods from 45 lactating cows. Vitamin A and beta-carotene in plasma and milk were analyzed within 48 h after collection. Total vitamin A equivalent (2 X amount of beta-carotene plus amount of vitamin A) also was calculated. Additionally, the total amount of vitamin A and beta-carotene excreted in milk was calculated from concentrations of vitamin A and beta-carotene in milk and milk weights recorded on sampling day. Independent effects of lactation number, period of collection, days in lactation, and California Mastitis Test Scores (the highest test score of four quarters used in the analysis) were examined by least-squares procedures using each blood and milk measure as the dependent variable. Results showed a highly significant independent effect of California Mastitis Test Scores for concentrations of plasma vitamin A, beta-carotene, and total vitamin A equivalent. Cows with lower plasma vitamin A, beta-carotene, and total vitamin A equivalent had higher test scores than cows with higher vitamin A and beta-carotene. Similar comparisons for amount of milk vitamin A, beta-carotene, and total vitamin A equivalent and total amount of each component excreted in milk showed no significant independent effects attributed to California Mastitis Test. Therefore, low concentrations of vitamin A and beta-carotene in plasma were associated with severity of mastitis in cows.

Various regression equations for estimating solids-not-fat in herd milk samples were calculated from 12,826 samples from 300 herds in one data source and 356 samples from 29 herds in another. Accuracy of estimating solids-not-fat is about the same when any two of the three independent variables (number of beads down, milk fat per cent, and per cent protein) are part of the regression equation. Little increase in accuracy was obtained when quadratic independent variables were included in the equations. Equations involving beads and protein per cent were slightly more accurate than equations involving beads and milk fat per cent. Fitting separate equations to different milk fat percentages appreciably improved the accuracy of estimating solids-not-fat only when the equation did not include the milk fat per cent as an independent variable. These results indicate the choice of the equation among those used in this study to estimate solids-not-fat in milk could be made by weighing the operational costs of the various equations rather than the predictive accuracy of the equation.

Seventeen milk pricing systems were applied to herd milk data to determine their effect on the price of milk received by producers. The systems included different values for fat, protein or solids-not-fat, and water. Each system was forced to distribute the same sum of money for the total pool of milk. The blend price equation of the Inland Empire Federal Milk Marketing Order, October 1969, was used to determine value of the pool. Maintaining the present fat differential (8.3 cents) and adding a value to either solids-not-fat or protein economically favored producers of milk with high fat test. Lowering the fat differential to either 6.5 cents or 4.5 cents and adding values for solids-not-fat economically favored producers of milk with low test. Placing a differential on protein and lowering the fat differential to 6.5 cents and in one system to 4.5 cents placed producers of milk with high fat test at an economic advantage. Systems with a fat differential of 4.5 cents and lower values for protein economically favored producers of milk with low fat test.

The economic effects of changing the milk producing characteristics of dairy cows were evaluated. Special emphasis was on milk composition. Energy requirements for formation of the different milk components were derived from theoretical energy efficiencies of the formation of fat, protein, and lactose of milk along with current National Research Council recommendations and the gross energy content of milk components. Metabolizable energy requirements for formation of 1g of fat, protein, and lactose were 16.3, 8.5, and 6.6kcal. Under the present milk pricing system and assumed feed costs, the approximate change in income over feed costs expected from a .1% increase in either fat, protein, or lactose content of milk for a lactation of 7272kg was +$12.78, −$2.51, and −$1.95. Such returns are indicative of the economic weights to put on milk solids in the development of selection indices under the present pricing system.

An on-campus intern program is used as an aid in teaching dairy cattle management. The program involves 12 students who operate and manage a herd of 30 cows. The program offers participating students the opportunity to acquire experience and skill in dairy husbandry and herd management, to accept and discharge responsibility, and to develop leadership and interpersonal relationship skills. The program has met with high success and is supported widely by students and industry.

Substituting the Golding plastic bead density of skimmilk for that of whole milk reduced the error of estimation from regression (SD) for the solids-not-fat in milk. However, the greatest reduction was when per cent protein in skimmilk, beads sinking in skimmilk, and per cent fat in the whole milk were used in the regression equation. Protein in skimmilk in the regression equation did not reduce the standard deviation as much in comparison with per cent protein in whole milk as comparing equations with beads sinking in skimmilk with beads sinking in whole milk. The standard deviation of all equations ranged from 0.096 to 0.139. For speed and accuracy the best method for large numbers of analyses should be based on regression coefficients for per cent fat and protein in whole milk. The choice of the regression equation, among those tested, would depend upon the laboratory and its sophistication.

Holstein calves were assigned to treatments of 1) pelleted prestarter (22% protein and 12% fat) and starter containing 10% alfalfa; 2) prestarter and starter containing 20% alfalfa; 3) no prestarter and starter containing 10% alfalfa; and 4) no prestarter and starter containing 20% alfalfa. Calves assigned to treatments 1 and 2 were fed 3.64 kg milk/d for 2 wk and calves assigned to treatments 3 and 4 were fed 3.64 kg milk/d for 3 wk and 1.82 kg milk/d for wk 4. Calves on treatments 2 and 3 were heavier at 10 wk but body weights and heights were similar by 6 mo. Rumen fluid and plasma measures were similar among treatments. Bull calves were assigned to treatments 1 and 3 and necropsied at 3 or 6 wk. Dry feed intakes to 3 wk and volatile fatty acid concentrations were greater for calves on treatment 1 than those on treatment 3. Wet weights of the empty reticulorumens were greater for calves on treatment 1 than those on treatment 3. Papillary development was not affected by weaning system. Calves weaned at 17 d and fed a prestarter have earlier rumen development than calves fed no prestarter and weaned later.

Effects of prepartum dietary crude protein on growth hormone, insulin in blood plasma, and subsequent reproduction and lactation were investigated in 30 Holsteins. Cows were fed either 80 or 100% of the crude protein recommended by National Research Council starting about 60 days precalving. Postcalving all animals were fed according to recommendations. Blood was sampled on days 220 (start of experiment), 250, 270, and 280 of gestation and on days 10 and 30 postpartum. Cows fed 80% crude protein prepartum showed decreased intake of dry matter and urea nitrogen in blood plasma prepartum, and yields of milk and total solids decreased by about 15%. Body weight changes through 30 days postpartum were not significantly different between treatments. There were no significant differences for growth hormone and insulin except growth hormone tended to be higher on day 270 of gestation for cows fed 80% crude protein. Insulin was negatively correlated with lactation number −.51 to −.56. Reproductive efficiency was similar between treatment groups. Lower crude protein intake during the dry period decreased dry matter intake and yields of milk and total solids.

The effect of four levels of progesterone on the occurrence and intensity of estrous behavior was determined in ovariectomized cows. Twelve Holsteins were bilaterally ovariectomized at least 2 mo before treatment. Progesterone (P4) was administered im two times/day for 5 d followed 72 h later with 2 mg estradiol (E2) im to induce estrous behavior. Treatments were control = oil, 100 mg P4/d, 300 mg P4/d and 500 mg P4/d. Each animal received all P4 treatments in a 4 X 4 Latin-square design. From d 2 through 6, with d 1 being the first day of P4 treatment, serum P4 concentrations averaged .3, 2.5, 6.1 and 12.3 ng/ml in treatments I to IV, respectively. Progesterone levels at the time of peak E2 (d9) were less than 1 ng/ml for treatments I, II and III and 1.8 ng/ml for treatment IV. Peak E2 levels for all groups averaged 23.9 pg/ml (12 h after E2 injection). Cows were observed continuously for 48 h after E2 injection to quantitate estrous behavior. Behavioral traits measured were: mounts initiated, mounts received, standing when mounted, chin rests initiated and chin rests received. Progesterone treatment caused a decrease in frequency of all five traits measured. As P4 levels increased, there was a linear (P less than .01) decrease in frequency of a behavioral trait. The percentage of the cows that showed each behavioral trait and mean time to first occurrence of each trait were not different after progesterone treatment, with the exception of standing behavior.(ABSTRACT TRUNCATED AT 250 WORDS)

Lipolytic adaptations of bovine adipose tissue during late pregnancy, lactation, and dry period were studied in Holsteins. Treatment groups consisted of first lactation daughters of high or low bulls based on Predicted Difference for milk. Heifers were fed either a 60% concentrate, 40% hay diet or a 40% concentrate, 60% hay diet from 0 to 140 d lactation. Feeding a low energy diet for the first 140 d of lactation did not affect adipose tissue lipolytic rates measured in vitro. Epinephrine and norepinephrine responsiveness of bovine adipose tissue increased prior to parturition, increased further in early lactation, then remained elevated during lactation and into the dry period. This responsiveness was unaffected by feeding low energy diets. Basal glycerol release in high genetic merit heifers was 64, 17, 40, 23, 20, and 42% greater than in low genetic merit heifers at -30, -15, 30, 60, 180, and 349 d about parturition. Response to norepinephrine was 15, 20, 18, and 15% greater in high genetic than low genetic merit heifers and response to epinephrine was 12, 20, 14, and 50% greater in high genetic than low genetic merit heifers at 30, 60, 180, and 349 d postpartum. The lack of a dietary energy restriction effect on lipolysis in early lactation suggested that these rates were near the physiological maximum for those animals. Rates of lipolysis were positively related with milk fat production. This study indicates a genetic component in adrenergic regulation of lipolysis in adipose tissue, independent of energy balance, in supporting lactation.

Effects of genetic selection for milk secretion and dietary energy restriction on adipose tissue lipid synthesis were tested in first lactation Holsteins. Daughters of bulls of 795 kg or 167 kg of Predicted Difference, base 1974, for milk had a 305 d first lactation of 8626 and 7038 kg of milk at 3.02 and 2.71% milk fat, respectively. Animals of each genetic group were allotted to treatments of a diet of 40% hay and 60% concentrate or of 60% hay, 40% concentrate ad libitum from 0 to 140 d of lactation. First lactation heifers fed the low energy diet ate 19% less net energy and produced 7% less milk of 28% more milk fat percent compared with heifers fed the high energy diet. Lipogenesis rates at 15, 30, 60, and 180 d postpartum in heifers fed low energy diets were 107, 66, 21, and 166% of those in heifers fed high energy diets. Rates of lipogenesis in adipose tissue of heifers of high genetic merit were 40, 10, 45, and 66% of those in low genetic merit heifers at 15, 30, 60, and 180 d postpartum. Lipogenesis in bovine adipose tissue homeostatically adapts to decreased energy intake and home orhetically adapts to genetically selected increase in milk fat secretion.

Semen from each of 10 Holstein bulls was extended to 15 X 10(6) total spermatozoa per dose in egg yolk-Tris and in egg yolk-Tris containing 20% (vol/vol) heat-treated heifer serum. Semen was used during 12 mo by 11 herdsmen-inseminators in four commercial dairy herds to inseminate 2820 Holstein cows on the first postpartum service. Percentage conception of cows free of clinical disorders at breeding was determined by rectal palpation at 30 to 60 days after insemination. Addition of serum to the extender did not influence percentage conception. A significant interaction of bull x seminal treatment was found. Least squares means of percentage conception to first service ranged from 45.3 to 59.9% among the 10 bulls. When bulls were classified as either high (greater than 55%), average (50 to 55%), or low conception (less than 50%), approximately 200 first services were required to classify correctly 80 to 90% of the bulls. Least squares means of conception rates ranged from 40.1 to 62.7% among the 11 herdsmen-inseminators. 1) Addition of heat-treated homologous heifer serum to the extender does not influence conception in a predictable fashion; 2) fertility inherent to the bull significantly influences conception; and 3) inseminator skill affects conception greatly.

Effects of management and environmental factors on reproductive performance were evaluated as part of a fertility experiment in four large commercial dairy herds. The herds were selected because they utilized routine herd health programs, kept complete reproduction records on all cows, were enrolled in Dairy Herd Improvement, and would follow the protocol of the experiment. Only data from first services following parturition were utilized, and conception was determined by rectal palpation. Information on over 2800 experimental breedings was collected during 13 mo. Percentage conception to first service was not affected by milk production during current or previous lactations. However, cows with higher production during current or previous lactations. However, cows with higher production during current or previous lactation had longer intervals to first service. Previous days dry did not affect conception or interval to first service significantly. Conception was less for cows with less than 50 days to first service (32%) than for cows with over 50 days to first service (49 to 57%). No differences were found among 10-day intervals to first service of over 50 days. Cows in third and later lactation had lower reproductive performance than cows in first or second lactation. Month of breeding did not affect conception significantly but did affect interval to first service. However, no seasonal trends were apparent. Differences among herds were significant for both conception and interval to first service.

We assessed the damage to frozen semen packaged in French straws stored for 2 yr in 60 on-the-farm semen tanks on 56 Washington dairy farms. Percentage of motilic spematozoa and percentage of spermatoza with intact acrosomes were not affected significantly by position of the semen on the rack (top or bottom goblet). The semen in 3 of the 60 tanks was lost to tank failure.

A method of combining predicted differences for milk and fat into an economic index for bull selection is explained. The relative emphasis to place on milk and fat will depend on the price of milk and on the fat differential of the payment schedule.

Immunoglobulin G1 concentration (IgG1) was measured in presuckle colostrum and calf serum obtained at 36 h and at weaning from inbred and straightbred Angus, Brangus, Hereford, Red Angus and Simmental cattle. Sources of variation considered as dam traits examined for IgG1 in colostrum and 36-h calf serum included line of sire, sire within line, age, and linear regression of IgG1 on inbreeding of dam. Only line of sire and inbreeding of dam were significant in the analysis of 36-h calf serum. Sources of variation considered as calf traits examined for IgG1 in calf serum at 36 h and at weaning included line of sire, sire within line, sex of calf, age of dam, and regressions of calf serum IgG1 on inbreeding of the calf and on dam's colostral IgG1. Only sire within line and the regression on dam's colostral IgG1 were significant for calf serum IgG1 at 36 h. Large differences existed in 36-h calf serum IgG1 between sires both within lines and when lines were ignored. Calves with 36-h serum IgG1 of less than 10 mg/ml were two to four times more likely to die before weaning than calves with higher IgG1 levels. The heritability estimates of IgG1 by paternal half-sib analysis were .41 +/- .30 for colostrum measured as a trait of the dam and .56 +/- .25 for 36-h. calf serum and .05 +/- .17 for calf serum at weaning considered as a trait of the calf. These estimates indicate that IgG1 in colostrum and 36-h calf serum could be increased by selection.(ABSTRACT TRUNCATED AT 250 WORDS)

Presuckle colostral samples and lamb serum samples taken 36 h postpartum were assayed for immunoglobulin G1 (IgG1) concentration (mg/ml) using single radial immunodiffusion. Breeds sampled included Polypay (P), Rambouillet (R), Targhee (T), Columbia (C), Finnish Landrace (F) and Finn crosses (Fx). Sources of variation examined in IgG1 concentration in colostrum (dam trait) included dam's sire breed, dam's sire, age of ewe and number of lambs born. All sources of variation were statistically significant. Least-squares means of IgG1 levels for sire breed were 80, 64, 67, 64, 72 and 69 mg/ml for P, R, T, C, F and Fx breed groups, respectively. A fetal stimulus may exist to increase the mass of IgG1 in colostrum available for multiple births (61, 69 and 77 mg/ml for single, twin and triplet, respectively). Ewe age was a significant source of variation because of a high mean concentration of IgG1 in the yearling's colostrum (100 mg/ml), whereas only slight differences occurred between the other age groups (65 to 67 mg/ml), except for the 7-yr older group (53 mg/ml). Sources of variation examined in IgG1 concentration of lamb serum at 36 h postpartum (lamb trait) included lamb's sire breed, lamb's sire, age of dam, birth type and sex, with dam's colostral IgG1 concentration and day born as covariates. Sire within breed, birth type and the two covariates were significant. Least squares means for sire breed were 36, 32, 33, 32, 31 and 32 mg/ml of serum for P, R, T, C, F and Fx groups, respectively. Lamb serum IgG1 decreased as birth type increased. The heritability of IgG1, estimated by paternal half-sib analyses, was .19 +/- .12 for colostrum and .18 +/- .06 for lamb serum.

The objective of this study was to compare conception to artificial insemination (AI) services in dairy cattle when semen was deposited into the uterine body or into both uterine horns (cornual insemination). Nine herdsman inseminators (HI) in four commercial dairy herds in Washington constituted the experimental units. Herds ranged in size from 393 cows to 964 cows. The duration of the experiment was 12 mo in three herds and 18 mo in the fourth herd. At the beginning of the experiment all inseminators were trained to deposit semen in the body of the uterus. Inseminators were instructed to use this method for 6 mo. Following employment of body deposition, the same inseminators were retrained to deposit one-half of the semen into the right uterine horn and one-half into the left uterine horn. Cornual inseminations were performed for 6 mo. A total of 4,178 services constituted the data set. Milk samples were collected from cows on the day of insemination and later were assayed for progesterone (P4). There was variation (P less than .01) in conception associated with month of insemination and insemination method (P less than .001). The monthly variation was not associated with season of the year. Least squares means for conception when semen was deposited in the uterine body was 44.7%, compared with 64.6% when cornual insemination was employed. The insemination treatment X inseminator interaction was not significant. Results suggest that cornual insemination provides an alternative to deposition of semen in the uterine body.