Progesterone (P4), luteinizing hormone (LH) levels and ovarian activity in postpartum Santa Inês ewes subject to a male effect

Abstract

Abstract. This study aimed to establish P4 and luteinizing hormone (LH) levels and ovarian activity as approaches to monitor the cyclicity of ewes under postpartum anestrus after the male effect approach. Santa Inês females (n = 66) were evenly distributed into experimental groups where they were brought into contact with an intact male during the postpartum period of 35 to 40 days (T1) and 55 and 60 days postpartum (T2). Ewes were isolated from males for 30 days before the onset of the experiment. Estrus events were detected in 93.30% (T1) and 100 % (T2) of females. Mean P4 concentrations (η g mL −1 ) before and after mating were 0.53 ± 0.17 and 4.55 ± 0.24 (T1) and 0.73 ± 0.06 and 4.90 ± 0.11 (T2), respectively, and concentrations were found to be lower (P < 0.05) before contact between genders. Preovulatory peaks of LH (η g mL −1 ) were evaluated at 42 (T2) and at 80 h (T1) after exposure to males, with mean ovulatory follicles of 7.90 ± 0.31 (T1) and 8.50 ± 0.30 mm (T2) and a mean number of ovulations of 1.50 ± 0.54 (T1) and 1.60 ± 0.51 (T2). Pregnancy rates were 85.70 % (T1) and 93.3 % (T2), with no difference (P > 0.05) between groups. Results showed that the male effect was effective for inducing and concentrating the occurrence of estrus in postpartum ewes that had lambed within 35 to 60 days previously. Moreover, preovulatory LH peaks occurred within 80 h after physical contact between genders, which led to follicle luteinization and increased P4 concentration, without compromising pregnancy rates. The male effect can be used with postpartum ewes that had lambed within 35 to 40 days previously in order to decrease time between deliveries.

<b>Reproductive cycles in white Karaman ewes: comparison of ovarian hormone secretion and reproductive behavior in non-pregnant and pregnant ewes in semi-intensive conditions

“…These results showed that WK has a comparatively long breeding season when compared with other northern hemisphere sheep breeds (Bartlewski et al, 1999a;Dell'Aquila et al, 1988;Gómez-Brunet et al, 2008). The results from our anestrous P4 levels were also similar with anestrous P4 levels from other sheep breed (Ferreira-Silva et al, 2017;Sasa, Rodrigues, Nonaka, Balieiro, & Coelho, 2016).…”

Technologies Used in Production Systems for Santa Inês Sheep: A Systematic Review

“…For example, the exposure of the male to the female with temporary weaning for 24 h improved the reproductive performance in ewes under postpartum anestrous ( 54 ). Also, the male effect promotes pre-ovulatory LH peaks up to 80 h after physical contact ( 55 ).…”

The effect of prostaglandin and gonadotrophins (GnRH and hCG) injection combined with the ram effect on progesterone concentrations and reproductive performance of Karakul ewes during the non‐breeding season

“…(2005) reported that the ewes may be synchronized using either GnRH‐PGF2α program or two injections of PGF2α 10 days apart. Ovarian activity of postpartum (35 to 60 days after lambing) ewes was resumed by the ram effect (Ferreira‐Silva et al., 2017). So, the male effect is efficient to induce ovarian activity and increase progesterone concentration in the control ewes.…”