The birth weights and weaning weights of Bos indicus cross calves from 4 inter se mated herd groups in a dry tropical environment were studied. The calving season commenced in late October, about 2 weeks before the start of the pasture-growing season. Second and subsequent generations of 1/2 Brahman and 1/2 Sahiwal crosses and first backcross, and later generations of 3/4 Brahman and 3/4 Sahiwal crosses, were represented. The Bos taurus component of the crosses was primarily Beef Shorthorn. In general, Brahman crosses were heavier at birth and grew faster to weaning than Sahiwal crosses (P<0.05), with consequent advantages in weaning weights of 11 and 6 kg in first backcross and late generation crosses, respectively. There was a birth weight advantage (P<0.05) of 1/2 crosses over 3/4 crosses, which was eroded by the time of weaning. Superior growth rates of 3/4 crosses were primarily expressed in years with greater nutritional stress and appeared to be due to better adaptation to environmental stresses by the calf. The only difference between filial generations was the growth rate advantage (P<0.05) of F2 1/2 crosses over F3 1/2 crosses, apparently due to suckling of F1 and F2 dams, respectively. Males exhibited an 8% average advantage (P<0.05) over females for all weight and growth traits in late generation calves. Calves with mature dams were 1.8 kg heavier (P<0.05) at birth. This, along with their higher (P<0.05) preweaning growth rate (19-49 g/day), resulted in calves with mature dams being 4-10 kg heavier (P<0.05) at weaning than calves of young cows. Differences between years in birth weights and preweaning growth rates were <25% (P<0.05). Birth weight was affected by nutrition of the dam in late pregnancy (early calves were generally about 1 kg lighter than late calves), and growth of calves was higher in years when the pasture growing season commenced earlier.

Postweaning growth to slaughter at 42 months of age in males and to initial mating at 27 months of age in females was studied in 4 inter se mated Bos indicus crosses in a dry tropical environment. Six-monthly growth periods from weaning (at about 6 months of age) generally coincided with wet and dry seasons. The cattle represented were second and subsequent generations of 112 Brahman and 112 Sahiwal crosses and first backcross and later generations of 314 Brahman and 314 Sahiwal crosses, The Bos taurus component of the crosses was primarily Beef Shorthorn. Annual growth averaged 300 g/day, with annual gain ranging from 60 to 180 kg. Average growth rates were about 50 g/day in the dry season (-352 to +374 g/day) and 500 g/day in the wet season (221-830 g/day). Postweaning growth of Brahman crosses was about 4% higher than Sahiwal crosses, with most of this advantage expressed in wet seasons. Sahiwal crosses were earlier maturing than Brahman crosses. Wet season growth was higher in 314 crosses than in 1/2 crosses, which probably reflected significant environmental stress in this period. Higher growth of 3/4 crosses tended to be maintained during dry seasons. Calves born late in a wet season grew more rapidly in dry seasons than early-born calves, so that liveweight differences which were apparent at weaning were reduced by one-third at 24 months of age. The difference between liveweights of weaners with young dams and those with mature dams was also reduced from 12-18 kg to 5-6 kg by 24 months. Dressing percentages of 3/4 cross steers at slaughter were 0.6 units higher than in half crosses, with no difference between Brahman and Sahiwal crosses. Sarcomere lengths, Warner-Bratzler shear force values, and Instron compression values together showed that M. longissimus dorsi muscle samples from 1/2 Brahman steers were the most tender of the breed crosses studied. Samples from Sahiwal cross and 3/4 Brahman steers appeared most affected by connective tissue toughness. Those from 3/4 Sahiwals appeared most affected by meat processing factors, causing them to be the least tender.

We studied protein metabolism in Holsteinized black-and-white cattle. The researches were conducted in the Kuzbass at OJC «Vaganovo». Blood sample was taken from each cow, according to generally accepted of methods and analyzed in the laboratory of biochemistry from Novosibirsk State Agrarian University by using standard kits of biochemical studies on a biochemical semiautomatic analyzer Photometer 5010 V5 +. The indicators of protein metabolism were established in the blood serum of Holsteinized black-and-white cattle in average values; creatinine was characterized by the lowest phenotypic variability. The greatest positive relationship was found between albumin/globulin coefficients and albumin (r = 0.765). The reference intervals were calculated for cows of the 3rd lactation of the Holsteinized black-and-white breed with a high level of milk productivity (9-10 thousand kg): total protein 62.02-87.58 g / l; albumin 21.05-36.09 g / l; urea 2.2-4 mmol / l; creatinine 50-71 μmol / l; albumin-globulin coefficients 0.35-1.16. The data obtained can be used for assess the interior of animals.