Abstract
Studies have revealed that despite the selection, the Holstein cows have a high genetic potential of milk production and in all lactations it is good in the specific conditions of the hot climate of Uzbekistan. The milk production level of German cows for the first lactation was 6511.2 kg of milk with a fat content of 3.84%, the Dutch — 6653.0 kg with fat content of 3.95%, and local breed — 6495.2 kg with a fat content of 3.95%. All mature cows retained high milk production, for III lactation and older it was 7112.5 kg and 3.90%, 7266.0 kg and 3.90%, 6847.5 kg and 3.94%, respectively. The yield of Dutch breeding cows was higher for 1 lactation by 141.80–157.8 kg, for III lactation and older by 153.5–418.5 kg, the yield of milk fat by 12.8–6.3 kg, respectively, of indicators peers of German and local selection. The cows of the studied selections combined well with high milk yield and fat content. The level of 4% milk for the studied lactation in all cows was quite high and testified to its good nutritional value. Holstein cows of different breeds are distinguished by a strong dairy type. For I lactation, for every 100 kg of live weight, 1,159.0–1265.5 kg of milk was produced, for III lactation and older - 1200.0–1308.6 kg.
It is revealed that milk productivity depends on the level of live weight of cows. The increase in body weight of cows in all groups provides an increase in milk yield, milk fat yield, milk yield of 4% milk. Milk productivity is interrelated with the duration of the service period. In group I, cows with a service period of 91–100 days were more productive, in group II, 81–90 and in group III, up to 80 days. The use of Holstein cows for the production of milk is effective and ensures an increase in its production, the creation of highly productive dairy herds and the production of high-quality maintenance stock.
KEYWORDS: Holstein breed, herd, milk yield, milk, fat, selection.