Reproductive ability of cows and their descendants of different generations
Abstract
The research was carried out on cows of Ukrainian Black-and-White Dairy breed and their descendants of the first and second generations on the conditions of LLC “Veletenj” in the Glukhiv district of the Sumy region. In cows, based on a retrospective analysis of data and the results of their own searches, was studied the age dynamics of reproductive capacity of cows for the first-seventh and higher lactation, and their daughters and granddaughters for the first and higher lactation. It has been established that reproductive ability of cows to some extent is due to their age. Depending on the lactation, the duration of the parturition of the cows of LLC “Veletenj” varied from 278.2 to 280.0, the duration of the indifference period – from 64.4 to 69.0 days, service period – from 123.5 to 136.4, inter-calving period – from 402.2 to 414.8 and in the dry stable period – from 61.3 to 75.8 days, the reproduction rate was 0.91–0.93, the calves output for 100 cows was 90.9–93.0 the index of insemination is 2.41–2.56 and the fertility index is 42.2–44.8. The results of our research indicate that each subsequent generation of cows was characterized by a better reproductive ability, which, in our opinion, is due to the timely abandonment of fetuses and stimulation of infertile cows, as well as an improved level of feeding. The difference in the duration of the service period for the first lactation between the mothers and their daughters was 24.5, for the best lactation – 24.8, for the duration of the interotional period – 24.8 and 23.7 days, respectively, at P < 0.001 in all cases. A more significant difference in reproductive performance was observed between cows and their granddaughters. In terms of the duration of the service period for the first and best lactation, it was 15.5 (P < 0.05) and 33.3 (P < 0,001) and interotional period – 17.3 (P < 0.05) and 33,2 days (P < 0.001) respectively. Between the majority of the studied reproductive abilities of mothers and daughters for the first and higher lactation, the relative variability was positive and reliable, and mothers and granddaughters – low uncertainty and mostly negative (exception – the duration of calving). The highest positive correlation coefficients were observed between the duration of cervix and their daughters (r = 0.113 ± 0.039 at P < 0.001) and granddaughters (r = 0.211 ± 0.088 at P < 0.05) for the first lactation, as well as mothers and daughters for higher lactation (r = 0.114 ± 0.039 at P < 0.01). Between indicators of the indifference period (r = -0.036–0.051) and the index of fertility of cows (r = -0.080–0.014) and their descendants for the lactation under investigation have low, multidirectional, unreliable connections. The influence of mothers on indicators of reproductive function of descendants is established. They made the most significant impact on the duration of service and inter calving periods, reproduction rate, calving out of 100 cows and the index of daughter insemination (ηx2 = 27.57–52.22%). For higher lactation, this effect was significantly lower (exception – the index of insemination) – ηx2 = 15,39–28,10%.
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