Bìol. Tvarin, 2018, volume 20, issue 3, pp. 55–68

INDICES OF RENEWAL OF EWE SEXUAL ACTIVITY AND ITS CORRELATION WITH AGE, WEIGHT, TRADITIONAL REPRODUCTIVE TRAITS AND CLIMATIC CONDITIONS

I. V. Lobachova, O. V. Ivanyna

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Institute of Animal Husbandry in Steppe Regions “Ascania-Nova” named after M. F. Ivanov’s —
National Scientific Selection-Genetic Centre of Sheep Breeding,
1 Soborna str., Ascania-Nova, Chaplynskyy district, Kherson region, 75230, Ukraine

To evaluate the quality of renewal of the sexual activity in ewes during the insemination campaign next indices were developed: IHi — the index of heat (0 or 1), IHTi — the index of heat time (from 1 to 4), ICTi — the index of conception time (from 1 to 4) and ILi — the index of lambing (from 0 to 3). Relationships between the indices and age, weight, part of animals with the heat (E%), fertility (F%), fecundity (Fm%), prolificacy (Pf) and climatic condition were researched. Data of Ascanian Merino ewes of 6 years was used.

Dependences between the indices and age, weight, change of weight and reproduction traits were non-linear. The IHi index was increasing with the rise of age, but after 6 years began to decrease. The mean IHTi index was the highest in the youngest and oldest animals indicating that the first heat delays in ewe lambs and ≥8-years old animals. Change of the ICTi index showed that the youngest and oldest animals had the lowest success to become pregnant during the first heat. Level of correlation between the weight and its change from the one side and the indices from the other was high (R>0.7) in young (≥2 years old) and moderate–noticeable (0.3<R<0.7) in more aged animals. The IHTi index had noticeable relationship with E%, F%, Fm% and low (R<0.3) with Pf, the ICTi index — high with F% and Fm% and low with Pf. The IHTi index reliably negatively correlated with the average air temperature in May and June, the ICTi and ILi — with mean temperature in July. The average humidity in June reliably positively correlated with E%, in July — with Pf.

It was supposed that the created indices may be useful to evaluate the efficiency of the applying of technological and selection approaches allowed to reducing of seasonality of sheep reproduction.

Keywords: EWE, REPRODUCTION, SEXUAL ACTIVITY, INDEX

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