Reproductive ability of Holstein cows of different ages under the industrial complex conditions

Abstract

The article presents studies results on the subject of reproductive capacity indicators of different ages high-yielding Holstein cows in the conditions of an industrial complex for milk production. The study was conducted on the basis of PJSC (Private Joint Stock Company) Agro-Soyuz in the Sinelnikovsky district of the Dnipropetrovsk region (Ukraine). The experimental groups of animals were formed in the following way: group I (n = 35) -first-calving heifers; group II (n = 35) -animals of the second lactation; group III (control), (n = 35) -animals of the third lactation; group IV (n = 35) -cows of the fourth lactation. Certain age dependence of the insemination index has been established. Young first-calving heifers and adult cows of the fourth lactation (groups I and IV) had a relatively better value of this indicator -4.5 units. At the same time, cows of the second and third lactation (group II; group III -control) were characterized by a sharp decline in reproductive ability, therefore, for one fertilization it was necessary to carry out 5.8 artificial inseminations for them. Based on the level of the insemination index by research groups, it was logical that the calving-to-conception interval for all experimental animals was much lower than the stereotyped value (60-80 days) and averagely amounted to almost 8 months. Infertility in animals of experimental groups was directly determined by the calving-to-conception interval duration and the average value of which was within 165 days. More infertile days were recorded in the dairy complex with group III cows (control) -195 days. The value of the adaptation index in the experimental groups was unaligned. Cows of the first two lactations (groups I and II) were characterized by this stable value of 7.6 units. After that, during the third lactation (group III -control), it was increased by 2 units -9.6, and in adult cows of the fourth lactation (group IV), it had a tendency to rapidly decrease to 4.8 units. First-calving heifers (group I) and adult cows (group IV) had the lowest production losses because they had the fewest infertile days. Animals of the third lactation (group III -control) were characterized by the highest production losses -0.68 calves and 3 166 kg of milk.