The influence of paratypical factors on the reproductive qualities of black-and-white cows of different ages

Abstract

The influence of paratypical factors (the age of mothers and the season of birth) on the indicators of reproductive qualities of black-and-white cows of different age periods has been studied. The studies were conducted on two groups of cows for the first and third lactation, depending on the influence of the age of the mothers, and on four groups – depending on the influence of the birth season. The shortest service period was characterized by the first-born heifers born from mother cows in the first calving (group I) - 96.4 days, which is 9.2% shorter than in animals from mother cows in the third calving (group II). It should be noted that, despite the longer service period, the cows of the first calving of group II did not show high productivity. The cows of group II (the age of mothers – the first calving) were characterized by a higher duration of the service period - 128.1 days, which is higher than in group I by 7.4%. The first heifers of group IV (autumn period of birth) were characterized by a lower service period - 95.8 days, which is 2.6 days. (2.7%) shorter in comparison with animals of group III (summer period of birth), by 8.9 days. (9.3%) - group II (spring period of birth), on 12.3 days (12.8%) - group I (winter period of birth). A shorter service period was observed in cows of group IV (autumn period of birth) – 116.5 days. The difference in the direction of increasing the service period with animals of group I was 11.7%, group II - 10.2% and group III - 4.0%.