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.

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.

Summary. Mice were exposed to 5 h of restraint stress on Days 1\p=n-\3,4\p=n-\6, or 1\p=n-\6of pregnancy in the morning (08:30\p=n-\13:30h, a.m.) or afternoon (13:30\p=n-\18:30h, p.m.). Stress reduced the pregnancy rate from 90 to 52% (P < 0\m=.\005) and average litter size on Day 18 from 8\m=.\2to 5\m=.\2 young (P < 0\m=.\005). Stress for 6 days was more effective than for 3 days (P < 0\m=.\005) and an a.m. stress was more effective than a p.m. stress (P <0\m=.\05)

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 D2O 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 9500 kg of FCM/305 d, were lactating, and were in less than average body condition. Eight days prior to slaughter, a single injection of D2O 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 D2O 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 x BW + 36.0 x body condition score, and -195.6 + .290 x BW + .927 x subcutaneous fat cell diameter; standard errors of the estimate were 4.6 and 5.5 kg, 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 D2O 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.

A deterministic simulation model was constructed to develop breeding objectives and estimate biological and economic values. The model simulates life-cycle production of a breeding cow and growth performance of her offspring. Input variables are divided into four categories: animal traits, nutritional variables, management variables and economic variables. The economic variables assume typical beef cattle production in Japan. The outputs from the model include cow-calf performance, feedlot performance and biological and economic efficiency. The model's ability to simulate herd composition, food intake of cow and calves, cow body-weight changes, empty body and carcass composition of feedlot animals and production efficiencies is illustrated.

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.

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.

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.