Performance indicators of cows depending on the age of the first fruitful insemination
The research was carried out in the breeding farms of the Udmurt Republic. The objects of research were heifers and cows of the black-and-white breed. Five groups were formed, depending on the age of fruitful insemination: Group I up to 14 months, Group II - 14,1 -16 months, Group III - 16,1-18 months, Group IV - 18,1-20 months, Group V - 20,1-22 months 2300 cows were analyzed. Up to 14 months, 12,4 % were fruitfully inseminated, from 14,1 to 16 months - 36,4 %, in the third group - 35,7 %, in the fourth group - 12,2 %, in the fifth - 3,3 %. The live weight of heifers at the age of 12 months in all groups was 322,3-344,1 kg, the highest live weight in the first group was 344,1 kg, which is 21,8 kg 6 more than in the fourth group. 8 % (p > 0,99) and the fifth for 21 kg or 6,5 % (p > 0,95). At the same time, during the first fruitful insemination, the first group's live weight is significantly lower than heifers that are fruitfully inseminated at a later date. The milk yield for 305 days of lactation is the highest in the third and fourth groups and amounted to 6,871 and 7,003 kg, respectively. Still, the service period's duration in these groups is also the highest and amounted to 174,1 and 170,6 days, which determines the high milk yield in the groups. The safety of cows for three lactations about the first is 35,8 to 48,4 %. The proportion of difficult calving and retention of the placenta is significantly higher in animals with a minimum (up to 14 months - 25,3 %) and maximum age (20,1-22 months) of fruitful insemination.