Influence of some factors on the lifelong yield of milk and duration of the productive use of cows
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The indexes of productive longevity and lifelong productivity of cows of black-pied breed are studied depending on paratypic factors. The greatest impact on variability of productive longevity and lifelong efficiency has the factor "milk yield in the first lactation" (η2 = 33.54 and 23.60%). Second in terms of influence factors were duration of service and the dry periods. On variability of a lifelong yield of milk influence of these factors (η2) made 10.40 and 9.81%; on duration of productive use – 10.29 and 10.60%. Factors "age at first calving" and "live weight at first calving" largely influenced on the variability of productive longevity - 6.10 and 7.64 % and slightly less on a lifetime milk yield - 3.83 and 5.55%.
Optimum parameters for increase in duration of use of cows and receiving the maximum lifelong efficiency were: age of the first calving is 32 months; live weight at the first hotel is 481-490 kg; distribute firstcalf heifers to level of 3500-4500 kg of milk; service period is 121-150, and dry period - 51-75 days.
Keywords: cows, black-pied breed, duration of productive life, lifelong yield of milk, factors of influence