[Reserves of dairy cow productive longevity]
2009
Moskalenko, L.P. | Konovalov, A.V. | Voronina, I.P.
Productive longevity and a lifetime production of dairy cows were studied in the Yaroslavl Region. It is shown that duration of practical use (DPU) influences on milk productivity of cows. The cows which have 10 and more lactations give milk in 9.4 times more than the animals which have 1 lactation. The cows which have no less than 6 lactations give the maximum average milk yield (6224 kg) and the ones which have 10 and more lactations give the minimum lactation milk yield (5524 kg). The highest return yield is fixed (22.5%) for the cows with DPU no less than 6 lactations. Productive longevity (a number of finished lactations and a lifetime productivity) characterizes by a high variability (Cv=45.9 and 51.8%). The average DPU is 4.1-5.3 lactations for Yaroslavl cattle breed; it is 4.04 lactations for Ayrshire breed; it is 3.8 lactations for Black-and-White breed. A line of breeding has the highest effect on variability of DPU, a lifeltime productivity and a maximum milk yield; a father does it in the limits of a line. Methods of linebreeding can increase cow longevity; pedigree Holstein bulls can also effect on this. The optimal longevity is in the limits from 1 to 6% of inbreedinglevel. The heredity coefficient for productive longevity is 0.16. A farm, a service period lenght, a live weight at the 1 calving and milk yield of the 1 lactation have an authentic effect on DPU and a lifelong productivity. A rejection coefficient increases at calving in early age (22-23 months). The named factors can be used as a selection criteria on productive longevity and cattle DPU in the Yaroslavl region
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