Abstract
In order to increase the number of replacement young animals and the terms of productive use, the dynamics of reproductive qualities of the first calving cows in the period from 2009 to 2016 and those who survived to the 5th calving (n=36 164) was analyzed. The data set is divided into groups of cows of different age of culling: Clvn – the group leaving after the n-th calving, Lclv – the group by the last calving with reasons for their culling: LP – low productivity, G&I – gynecological diseases and infertility, U – udder diseases, L – limb diseases. The following calving results in proportions were taken into account: Ab – abortions, Sb – stillborns, B – bulls, H – heifers, Mo – multiple offspring. It was revealed that the smallest proportion of cull animals at the first calving (9,2%), and the largest – at the third (27,1%) with a tendency to increase after Clv2 and Clv3 calving by 6,2 and 7,3% and, conversely, decrease at the age of 5th calving by 11.2%. It was found that the share of Ab in the studied sample in cows Clv1 is lower (from 0,10 to 0,60%) than Lclv (from 0,30 to 0,60%), and on Sb, on the contrary, indicators are higher for Clv1 (from 4,47 to 5,10%). There is a tendency for the sex ratio to shift towards B: their share in the offspring by Clv1 ranges from 48,3% in 2010 to 51,4% in 2016, and H from 45,2% in 2014 to 47,3% in 2010. The greatest losses in the breeding of dairy cattle are caused by culling for G&I cows, the share of which has decreased in recent years from 42.9% in 2009 to 32.0% in 2016 in Lclv and from 58,8 to 45,7%, respectively, by Clv1, and the share of analogues for Clv2 and Clv3 calving is significantly lower (40,5 and 36,2%, respectively). In this group of cull animals Clv2 and Clv3, the Ab is the second in value (on average, 0.54 with fluctuations from 0,51 to 0,65%, respectively). For active and effective reproduction of the herd, it is necessary to keep the maximum amount of heifers from Clv1 for introduction into the herd and to reduce losses from G&I.
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