Reproductive performance, metabolic and hormonal profiles of Santa Inês ewes in winter and summer under tropical conditions

Abstract

The study aimed to evaluate the reproductive, metabolic and hormonal profiles of Santa Inês ewes during winter and summer in the tropical climate of Rio de Janeiro State, Brazil. The ewes (n = 16) were prepared for induction of synchronised oestrus with a short-term hormonal treatment, and follicular dynamics were assessed with ultrasonography. Blood samples for biochemical and hormonal analyses were collected on days zero, six and eight of the protocol at 7, 13 and 19 h. Reproductive behaviour did not differ (P > 0.05) between seasons. Based on ultrasonography data, the ovulation rate was 100% in summer and 81.3% in winter. Most of the ewes showed double ovulation in summer, and the diameter of the largest and second largest follicles differed (P < 0.05) between seasons. Among the biochemical parameters, plasma glucose, plasma urea and serum albumin differed (P < 0.05) between the study periods. Regarding the hormonal profile, higher serum triiodothyronine, thyroxine and prolactin concentrations (P < 0.05) were observed in summer. The average progesterone concentrations demonstrated low reproductive seasonality. In conclusion, the reproductive performance of the ewes was superior in summer, and higher levels of plasma glucose and serum albumin during this season may have played a role in the observed ovulation rates. The higher levels of serum prolactin and serum thyroxine in summer demonstrated that these compounds were not involved in the regulatory mechanisms underlying the onset of anoestrus in these Santa Inês ewes under tropical conditions.

Evaluación de los parámetros de calidad seminal y cinemática espermática en tres razas ovinas de lana en condiciones de trópico alto colombiano

“…A pesar de esto, existe limitada información sobre cómo otras razas adaptadas al trópico exhiben actividad reproductiva durante todo el año (15). El objetivo del presente estudio fue evaluar el efecto del eyaculado y la raza en 4 periodos de colecta sobre los parámetros de calidad seminal y motilidad espermática en 3 tipos raciales ovinos de lana bajo condiciones de trópico alto colombiano.…”

Reproductive and fertility parameters of ewes from the Colombian tropical highlands

“…Progesterone levels normally drop on day 14 of the ovine estrous cycle (Bass et al 2017), which agrees with the present work. Balaro et al (2015) reported progesterone profiles of Santa Ines ewes in winter and summer under the tropical conditions of the state of Rio de Janeiro (Brazil) They found that about 50 % of the ewes had mean progesterone concentrations under 3.2 nmol/L, confirming the low reproductive seasonality in Santa Ines ewes.…”

Reproductive and oxidative status of ewes supplemented with vitamin C during oestrous synchronization and early gestation

“…In a study carried out on Santa Inés sheep which were synchronized with sponges (Progespon®), average glucose levels of 64.8 mg/dL were recorded during the summer and winter seasons (Balaro et al, 2015). On the other hand, MacLeod et al (1999) indicated that a low synthesis of ascorbic acid is observed in high-producing cows as a result of high glucose demands of the body, especially during the beginning of lactation.…”