Changes in the composition and properties of colostrum and milk from Angus and Black-and--White cows were described in successive milking runs on the first ten days after calving. The first test milking took place directly after calving, and successive milking runs – every 6 hours on the first day, every 8 hours on the second and third day and twice on the fourth day. The collected samples were marked for the basic composition and density of milk, its active acidity, thermostability and coagulability. In comparison with Black-and-White cows, colostrum and milk from Angus cows on the first ten days after calving were characterized by a lower fat and lactose content and a higher protein content. The technological properties of colostrum and milk from both breeds were less differentiated and remained within the reference range. The colostrum from cows of both breeds, obtained in the first twelve hours after calving, was characterized by very good composition and quality. A high quality of colostrum was maintained in the Angus breed during the first five days after calving. The obtained results indicate that long-term selection for increased yield caused significant changes in the composition of colostrum and milk.
The aim of this study was to determine relationships between the density of first-milking colostrum (collected within the first hour after calving), the composition of colostrum from subsequent milkings on the first day after birth and the performance of calves until 120 days of age. Cows that delivered bull-calves in the fall (October, November) were divided into three groups, depending on the specific gravity of first-milking colostrum: group I – below 1.047 g/cm³ (6 head), group II – 1.048 g/cm³ to 1.054 g/cm³ (6 head), group III – above 1.054 g/cm³ (7 head). Higher density of first-milking colostrum (cows of groups II and III) was correlated with higher concentrations of total whey protein and immunoglobulins. This correlation was observed until the second milking (6 to 9 hours after calving). Bull-calves fed colostrum of higher specific gravity were characterized by a faster growth rate, higher daily gains and greater body measurements, compared with those fed colostrum of lower density.
Stall fattening took from 0.5 to 1.5 year of animal life. The young bulls were fed with bulhy and addition of concentrated foods. The hybrids gained 520 kg of body weight. Average daily gain was 0.959 kg. The hybrids charakterized with lower food consumption of nutritive components for 1 kg gain. After slaughter they shawed 2.3% higher carcase yield. The black- -white young bulls charakterized with warse fattening results.
Thirty heifers of black-white breed, 30 heifers of charolaise x black-white hybrids and 26 heifers of simental x polish-red hybrids, grazed in one herd with pasture were investigeted. The obtained results showed that only posture breeding for grass fattening of black-white heifers as well as their hybrids ones be used. Behaviour analysis of animals showed greater herding intensity of hybrid heifers in comparison with black-white ones.