DOI 10.36461/NP.2024.70.2.020
UDC 636.2.082.4

REPRODUCTIVE ABILITY OF HOLSTEIN COWS OF DIFFERENT AGES
V.V. Lyashenko, Doctor of Agricultural Sciences, Professor; I.V. Kaeshova, Candidate of Agricultural Sciences, Associate Professor; A.V. Gubina, Candidate of Agricultural Sciences, Associate Professor; N.Yu. Chupsheva, Candidate of Agricultural Sciences, L.N. Zorin, Student
Federal State Budgetary Educational Institution of Higher Education "Penza State Agrarian University", Russia, е-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.

The reproductive function of an animal involves obtaining a similar animal for procreation. Reproductive abilities characterize the reproductive process more comprehensively.
The article presents the results of the evaluation of reproductive traits of highly productive cows of different ages. The study was carried out under the conditions of a modern dairy complex on a herd of Holstein cows with a milk yield of over 11,000 kg per cow. Three groups of cows of the first, second and third lactations were formed. The calving result, service period, dry period, milk yield, the relationship between service period length and milk yield, the insemination rate and the utilization coefficient of the reproductive ability of the cows were investigated.
It was found that mature cows produced more calves than first-calf heifers and second-calf cows, by 4.1 and 0.5 % respectively. Higher performance of heifers was observed in cows of the first (82.5 %) and second (64.8 %) lactations, which can be explained by the insemination of replacement heifers and first-calf cows with sexed semen. The duration of lactation is almost the same for animals in groups I and II and exceeds this indicator for cows in group III by 18.1 (p ≤ 0.001) and 11.5 days (p ≤ 0.01) respectively.
The highest milk yield for the entire lactation and for 305 days of lactation was observed in cows in the second group, namely 13,238.6 and 11,491.2 kg respectively. In terms of lactations, a shorter service period was observed in the cows of the third group, which amounted to 138.5 days. No correlation was found between milk yield and a service period. Most of the animals in the second (48.1 %) and third (50.0 %) groups were fruitfully inseminated from the second time and a significant part of the first-calf cows the fourth time (28.2 %). The utilization coefficient of the reproductive ability and calf yield was highest in third lactation cows.
The results of the study lead to the conclusion that the evaluated cows of the three groups are generally characterized by a satisfactory reproductive ability.
Keywords: cow, Holstein breed, reproduction, calving, heifer, service period, insemination, lactation, milk yield.

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