The relationship between milk productivity and reproduction in cows in highly productive Ayrshire herds

Abstract

The purpose of the study is to study the relationship between the rates of dairy productivity and reproduction of cows in the highly productive Ayrshire herds of the Republic of Karelia.Materials and methods. The work was performed on the basis of the four Stud of the Airshire rock at the "Megrega" trivial, "Ilyinskoe", Mayak LLC, Agrocomplex OJSC. V. M. Zaitseva "(Republic of Karelia). Data on dairy productivity and reproductive ability are collected and processed in 24,720 cows. Materials of zootechnical accounting and bonitations for 2004-2020 were used. At the end of the observation period, the productivity of the Stud was 7500-8500 kg of milk.From indicators of the productivity of cows, the amount of fishing, fat products for full lactation and 305 days of lactation, from the reproduction indicators - the duration of the service period, a dry period, an interstitial period (MOP), the age of the first calf, the age of cows during the selection, the causes of the selection are taken.The main biometric constants (X ̅, ϭ, CV) were calculated, the grouping method was used to characterize the signs of signs calculated the correlation coefficients.Results. The relationship between milk productivity and reproduction was studied in 4 Ayrshire herds of 24,720 cows with an average productivity of 7500-8500 kg of milk. A high positive relationship of milk yield and milk fat production with the duration of the service period (SP) was established, the correlation coefficient was up to 0.929 (P<0.001), which is consistent with the data of other researchers of this problem. It is shown that in herds with a milk yield of 8500-9000 kg of milk, the SP duration of 135-140 days is justified. It was noted that the decrease in the age of the first calving of cows led to an increase in the milk yield of the entire herd (r =-0.676; -0.686; P<0.05).A relatively short period of use of cows in herds was recorded – 3.5-3.7 lactations, while the milk yield of cows aged six lactations and older significantly exceeded the average milk yield for the herd. This leads to a positive correlation of the period of use of cows (r =0.935; P<0.001) and the proportion of cows with six lactation and older (r =0.788; P<0.05) with the milk yield of the herd. Cows with six lactations and older can stay in the herd, provided that their performance exceeds the average level of the herd. The influence of milk yield on the length of the service period and the MOP is manifested not only within one lactation, but also in adjacent lactation. It was found that with an increase in milk yield from less than 6000 kg of milk to 9500-10000 kg or more in the previous lactation, the duration of SP in the subsequent lactation increased from 112 to 170 days, MOP – from 391 to 436 (correlation coefficients from 0.138 (P<0.01) to 0.870 (P<0.001).Conclusion. The results obtained indicate the need to develop operating conditions for cows that provide a combination of high and record milk yield with normal reproductive abilities. In particular, to ensure maximum optimization of feeding conditions, maintenance, breeding and veterinary services, and control of animal health.