Resumen

ROLDAN-ROLDAN, Antonio et al. Puberty age in pelibuey ewes lambs, daughters of ewes with seasonal or continuous reproductive activity, born out of season. Agrociencia [online]. 2016, vol.50, n.4, pp.441-448. ISSN 2521-9766.

Some Pelibuey sheep do not present a reproductive seasonality that is common in the species. The objective of this study was to determine whether the Pelibuey ewe lambs, daughters of ewes with continuous (C) reproductive activity, begin puberty before the daughters of seasonal ewes (S), when the births occurred outside of season (autumn or winter). The ewe lambs daughters of continuous ewes do not rely on the photoperiod and begin their puberty during the anestrus. To test this, 16 Pelibuey ewe lambs (8C and 8S) born in autumn (November) and 21 ewe lambs (11C and 10S) born in the winter (December-January) were studied. All of them were kept with their mothers and weaned at 90 d of age; they remained in an intensive system and were isolated from contact with males. Starting at four months of age, the weight and body condition were recorded weekly, and blood samples were taken to determine the plasma concentrations of progesterone and to identify the beginning of the ovary activity. Through a variance analysis, the differences in the presentation of puberty between daughters of continuous and seasonal ewes were studied, in each birthing season, through age, weight, body condition at first ovulation, and differential of weight at weaning-weight at first ovulation. The age and weight at puberty was 239.25± 10.96 d and 29.78± 4.39 kg in the ewe lambs born in autumn, and 230.28± 42.71 d and 25± 4.42 kg in ewe lambs born in winter. None of the variables of the daughters of continuous ewes were different from those of seasonal daughters in any of the lambing seasons (p> 0.05). The age at puberty in Pelibuey lambs is independent of the reproductive pattern, seasonal or continuous, of their mothers. Some ewe lambs only need to be exposed to long days for puberty to take place.

Palabras llave : Puberty; lambs; Pelibuey; photoperiod; continuous reproductive activity; Ovis aries.

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