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Revista Brasileira de Zootecnia

On-line version ISSN 1806-9290

Abstract

MORAES, Gentil Vanini de et al. Frequency of estrus in Santa Inês, Texel and Ile de France ewes in the northwest of Paraná State, Brazil. R. Bras. Zootec. [online]. 2013, vol.42, n.10, pp.706-712. ISSN 1806-9290.  http://dx.doi.org/10.1590/S1516-35982013001000003.

The incidence of estrus in nulliparous Santa Inês (n = 16), Texel (n = 16) and Ile de France (n = 15) ewes fed two levels of crude protein (CP, 12 or 16%) was monitored from July 2005 to December 2006, and seasonality in the Santa Inês breed in the south of Brazil was characterized. The solar radiation data were recorded daily, and samples of blood were collected biweekly for determination of the plasma concentration of progesterone in Santa Inês lambs at, on average, 11±1 months of age. The female Santa Inês lambs, in the experimental period, stayed among teaser rams with a powdered-dye-ink mixture placed on their chest to mark the females that accepted to be mounted. Santa Inês ewes did not manifest estrus in the first fortnight of November and in December 2005, nor in the last fortnight of December 2006. Estrus activity was not observed on any of the three breeds in October 2006. Breeds differed at the level of 12% CP. Santa Inês and Ile de France females did not differ as for the probability estrus manifestation and both presented higher probabilities then Texel. When the effect of 12 or 16% CP on each breed was evaluated separately, it was verified that levels of 12 or 16% of crude protein did not change the probability of estrus manifestation in any of the studied breeds. The concentration of plasma progesterone in Santa Inês ewes during the spring of 2005 and 2006 indicated that there is difference between 12% CP (0.68±1.32 ng/mL) and 16% CP (1.28±1.99 ng/mL) and between the years 2005 (0.39±0.78 ng/mL) and 2006 (1.47±2.08 ng/mL), demonstrating the anestrous seasonality of Santa Inês in South Brazil.

Keywords : photoperiodic; progesterone; reproduction; seasonality.

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