PRODUCTION OF MILK AND ITS BASIC COMPONEN TS IN DAIRY-COWS OF THE SLOVAK PIED AND HOLSTEIN BLACK-PIED BREEDS AND IN THEIR CROSSBREDS

The paper presents an interpretation of milk production, content of fa t, proteins, dry matter, solids-not-fat (SNF) and lactose, live weight and persistence index in dairy breeds Slovak Pied (S) and Holstein-li ke Black-Pied Lowland (HBL) and their crossbreds F1, F11 (75% of HBL - 25% S), F101 (62.5% HBL - 37.5% S), F111 (87.5% HBL - 12.5% S), F1111 (93.75% HBL - 6.25% S) and F11111 (96.88% HBL - 3.12% S) from the Ist to the 3rd lactation. Dairy cows of all genotype groups were kept on 31 farms and they delivered their calves in the period from 1985 to 19 91. A total of 9,171 first, 6,722 second and 4,344 third lactations we re statistically processed. The results can be summarized as follows: In comparison with milk production of dairy cows of S breed, milk prod uction of F101 and F11 generation crossbreds was on average higher by 12.67% and 17.86% but it was lower by 26.31% and 8.33% than in HBL cow s. F101 crossbreds had the average content of milk fat amounting to 4. 04 g/100 g, while it was 3.99 g/100 g in F11 crossbreds. The content o f milk proteins was 3.32 g/100 g in F101 crossbreds and 3.27 g/100 g i n F11 crossbreds; dry matter content made 12.65 g/100 g and 12.49 g/10 0 g and the values for solids-not-fat amounted to 8.53 g/100 g and 8.4 9 g/100 g. Dairy cows of S and HBL breeds had the fat content of 4.13 g/100 g and 4.02 g/100 g, resp., while the protein content equalled 3. 37 g/100 g and 3.26 g/100 g. Milk production per day of life over the first three lactations on average: 5.79 kg milk in dairy cows of S bre ed, 7.47 kg in HBL dairy cows, 7.14 kg in F101 crossbreds and 7.37 kg milk in F11 crossbreds. The age of dairy cows at first calving: 869.3 days in dairy cows of S breed, 833.8 days in HBL cows, 852.0 days and 844.8 days in F101 and F11 crossbreds, respectively. Average live weig ht of dairy cows at third calving: 597.9 kg in S dairy cows, 589.3 kg in HBL, 606.9 kg and 610.1 kg in F101 and F11 crossbreds. The crossbre ds of F111, F1111 and F11111 generations (absorptive crossing) had the milk production per lactation on average higher by 17.67% to 23.73% t han did the dairy cows of S breed, but lower by 7.89% (F111) or basica lly the same (F11111) as the Holstein-like Black-Pied dairy cows. Fat content in the milk of these crossbreds ranged from 3.99 g/100 g (F111 ) to 3.95 g/100 g (F11111), dry matter and milk protein content from 1 2.41 g/100 g to 12.18 g/100 g and from 3.25 g/100 g to 3.17 g/100 g, r esp. Milk production per day of life (over the first three lactations) ranged from 7.35 kg (F111) to 7.88 kg (F11111). The live weight of cr ossbreds from absorptive crossing fluctuated from 614.4 kg (F111) to 5 97.5 kg (F11111). The age of crossbreds at first calving was 838.2 day s, 824.3 days and 828.3 days. Lactation persistence was highest in the first lactation; its values equated in the next two lactations or the y were negligibly higher.