Frequency of estrus in Santa Inês, Texel and Ile de France ewes in the northwest of Paraná State, Brazil

Abstract

-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.

Reproductive performance of European‐breed ewes in different seasons of the year under mid‐latitude

“…However, as Texel and Suffolk ewes showed lower PR when bred in spring, this could mean a shorter reproductive season for these breeds. At a latitude similar to that in the present study, Moraes et al (2013) also found less reproductive seasonality in the Ile de France breed compared with that in Texel; other studies also reported a marked seasonality in the Suffolk breed (Dufour, 1974; Jeffcoate et al, 1984). In the present study, females crossbred between European breeds did not show seasonality, corroborating the findings by Dufour (1974), who reported a greater duration of reproductive activity throughout the year for females crossbred between Suffolk, Dorset, and Leicester compared with pure females of the same breeds.…”

“…At a latitude similar to that in the present study, Moraes et al (2013) also found less reproductive seasonality in the Ile de France breed compared with that in Texel; other studies also reported a marked seasonality in the Suffolk breed (Dufour, 1974;Jeffcoate et al, 1984).…”

Melatonina associada à reprodução animal: uma abordagem das publicações científicas

“…O levantamento revelou que 90,54% (n=335) das publicações foram oriundas de pesquisas aplicadas usando animais e 9,46% (n=35) foram revisões de literatura. De fato, sabe-se que muitas raças de ovinos apresentam sazonalidade reprodutiva (MORAES et al, 2013). Os efeitos do fotoperíodo sobre o controle hormonal reprodutivo são mediados pela melatonina pineal e a sua secreção diária é proporcional ao comprimento da noite, ou seja, na presença da luz, a secreção de melatonina é inibida (COELHO et al, 2006).…”

Reproductive and Metabolic Responses in Ewes to Dietary Protein Supplement During Mating Period in Dry Season of Northeast Brazil

“…Currently, it has been suggested that the efficiency of oestrus synchronization treatments is subjected to the nutritional status of the animal before the hormone protocol (21) . In addition, several studies (24)(25)(26) have observed that protein level in the diet do not change the frequency of natural or synchronized oestrus in ewes, but it can increase the progesterone levels (25) . This information is consistent with our results, demonstrating that an increase in the protein level in diet for ewes maintained in adequate body condition did not show any significantly effect on number of animals in oestrus, but may affect the moment of estrus manifestation.…”