Keywords: selection, potential, variability, average daily growth, type of birth, inheritance
The research was conducted on young sheep of the Kharkiv internal breed type of the Prekos breed, born in 2020. in the conditions of the research farm of the Institute of Animal Science of the National Academy of Sciences “Gontarivka”. The influence of different intensity and types of selection, as well as the level of feeding on the manifestation of this trait in animals of two generations was evaluated. It was established that the indicators of average daily growth of lambs from birth to weaning from their mothers vary widely – from 38 to 591 g per day. At the same time, the average daily growth of singleton lambs in the selected groups M-, Mo and M+ exceeded the indicators of twins by 27.0%, respectively; 17.7% and 12.9%.
In two adjacent generations (500 pairs of mothers and their daughters), the coefficient of inheritance of this trait was calculated. It turned out to be low, h2 = 0.046, and the dependence of the average daily growth of daughters on the value of this trait in their mothers, according to regression analysis, has the following form: Y=241.85+0.022X. Modeling of selection in the generation of mothers with regard to the influence on the average daily growth of animals of the daughter generation established that the difference between the offspring of mothers of classes M- and M+ is only 1.1% in favor of the latter, and their advantage over to selection, the variability of the trait in the compared groups of mothers narrowed to 13.1–18.8%, while in the corresponding groups of their daughters, this indicator was 27.2–34.1% and was close to the mean values for the sample. And although in terms of average daily gains before weaning, the parent rams exceeded the mother stock by 20.6% (p<0.001), the maximum of this trait was only 391 g/day, while the ewes exceeded 500 g/day.
According to the calculated average daily growth potential, daughters should exceed their mothers by 10.4%, while in fact their advantage was almost 22%. This testifies to the influence on the degree of realization of this trait primarily by a complex of paratypic factors, to a lesser extent by parents, which allows us to conclude that there is a need to increase the selection pressure among future breeder rams and stabilize the feeding when raising lambs at a higher level.
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