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.

Study of peculiar features of protein metabolism of healthy colts in the first three months of life was realized in the conditions of the Republic of Belarus. Research results showed that there was a tendency of increasing of hemoglobin concentration up to 150,270+/- 4,73 g/l, number of total protein of blood serum – up to 60,33 +/- 1,33 g/l, and the decreasing of uric acid up to 97,33 +/- 10,72 micromole /l. Quantity of beta-1 and alpha globulin fractions of serum protein fluctuated a little – from 10,78 +/- 3,69% up to 8,44 +/- 1,24% and from 25,12 +/- 4,84% up to 22,06 +/- 4,93%, respectively. The most essential changes of protein metabolism were stated at two month old colts, which had urea concentration of 5,25 +/- 0,23 micromole/l, alanine aminotransferase activity – 66,92 +/- 3,16 units/l, creatine content increased up to 77,37 +/- 5,83 micromole /l; and there was the lowering of aspartate transaminase level up t159,5 +/- 8,1units/l. There was stated the lowering of albumin quantity up to 32,07 +/- 2,19%, and increasing of alpha-1, alpha2- and beta2- globulin fractions up to 7,52 +/- 1,23%, 14,98 +/- 1,41%, 11,82 +/- 1,04%, respectively. At the age of three months the quantity of urea and creatinine in blood serum of colts remained at the same level, alanine aminotransferase activity decreased on 21,56%, and aspartate transaminase increased up to 204,33 +/- 10,37 units/l. At this period the quantity of albumin fractions was 44,56 +/- 6,59%., concentration of alpha-1, alpha2- and beta2- globulins decreased on 10,64%, 30,04% and 34,52%, respectively

Determination of degree and relations between derangements of metabolic processes in calves with respiratory syndrome in the milking period was realized in the conditions of the Republic of Belarus. Research results showed that the calves with the respiratory syndrome had expressed metabolic processes disturbances, which were marked in the analyzed biochemical blood indexes (total protein; albumins; urea; creatinine; glucose; cholesterin; triglycerids; bilirubin; ALP; AAT; SGPT; calcium; phosphorous; magnesium; iron; manganese; cobalt; cuprum; zinc). In calves with respiratory syndrome there was noted the increased content of crude protein in blood serum (71,42 +/- 2,57 g/l P less than 0,05), low urea level (3,08 +/- mmol/l). There was the increased level of creatine (574,11 +/- 65,26 mkmol/l; P less than 0,01) and bilirubin (8,11 +/- 1,15 mkmol/l; P less than 0,05). Glucose concentration in blood of diseased calves was at below standard level (3,49 +/- 0,69 mmol/l). Glucose indexes varied and were changing during a day; and depended on muscular activity, intervals between feeding and hormonal regulation. Diseased calves had high cholesterol level in blood serum (4,07 +/- 0,34 mmol/l; P less than 0,05), which was stated in case of liver disease and hypothyroidism. Phosphor level was higher than the standard indexes of healthy calves (2,85 +/- 0,03 and 2,05 +/- 0,05, respectively). Content of magnesium, cobalt and zinc in blood of the diseased calves was lower than in healthy ones. Calves with respiratory pathology had protein, fat, hydro-carbonic and mineral metabolic processes