Body condition scoring (using a 5-point with quarter-point divisions) was performed on 66 Holstein dairy cows that began their second or later lactation in August, September, or October 1988. Cows' body condition was scored beginning on postpartum day 4 (+/- 1) and subsequently at postpartum days (+/- 1) 18, 32, 46, 60, 73 and 87. Blood samples were obtained on the same dates. Reproductive health examinations were conducted by 1 of 2 veterinarians beginning at postpartum day 21. Reproductive performance was evaluated in relation to body condition score and serum urea nitrogen and cholesterol concentrations. Number of days to first recorded signs of estrus and first breeding were not related to body condition score at calving, amount of condition loss, cumulative 80-day milk yield, or 305-day fat corrected milk yield. Cows that calved with body condition score greater than or equal to 3.50 required more days to conceive. Cows losing > 0.75 points of condition had longer days of conception. Body condition score at calving and amount of condition lost were not related to services per conception or diagnosis of follicular cyst. Cumulative 80-day milk yield was not related to days to conception or services per conception. Cows that produced greater than or equal to the mean 305-day milk yield required more services and had longer days to conception than cows that produced < the mean 305-day milk yield. Cows with diagnosis of ovarian follicular cysts had greater cumulative 80- and 305-day milk yields than did cows that were not diagnosed with follicular cysts. Cows conceiving with less than or equal to 2 services did not differ in average daily milk production, body condition score, or serum urea nitrogen concentration from cows conceiving with > 2 services, but cows that conceived with less than or equal to 2 services had higher serum cholesterol values than did cows requiring more services.

Nutritional and physiologic effects of clinically apparent and subclinical Ostertagia ostertagi infections were studied in 3 groups of 5 calves each. Group-1 calves were inoculated with 100,000 Ostertagia ostertagi third-stage larvae (L3)/calf/wk for 14 weeks. Group-2 calves were inoculated with 10,000 L3/calf/wk for 14 weeks, and group-3 calves were not inoculated. Calves in group 1 had decreased dry matter intake and feed utilization from 4 weeks after initial inoculation. Group-2 calves had no changes in dry matter intake, but had decreased feed utilization at 12 and 14 weeks. Calves with clinically apparent infections (group 1) lost a mean weight of 11.8 kg, whereas calves with subclinical infections (group 2) lost a mean of 46.6 kg, and control calves lost a mean of 60.7 kg. Calves with O. ostertagi infections (groups 1 and 2) also had decreased carcass quality at slaughtering, which was reflected in decreased dressing weights and increased water-holding capacity of the rib-eye muscle. Calves in groups 1 and 2 also had lower carcass yield and rib-eye muscle weight, and group-1 calves had decreased protein content. Results of hematologic, pathologic, parasitologic, and clinical examinations mirrored nutritional changes.