Balaro Mario Felipe Alvarez, da Fonseca Jeferson Ferreira, Oba Eunice, da Cruz Cardoso Elyzabeth, Brandão Felipe Zandonadi
Department of Pathology and Clinical Veterinary, Veterinary School, Universidade Federal Fluminense, Vital Brasil street, no. 64, 24320-340, Niteroi, RJ, Brazil,
Trop Anim Health Prod. 2014 Dec;46(8):1533-7. doi: 10.1007/s11250-014-0672-8. Epub 2014 Sep 25.
This study aimed to characterize the annual reproductive cycle of Santa Inês sheep in the Fluminense lowland region (latitude 22° 27' 45″ south, Rio de Janeiro, Brazil) between September 2011 and August 2012. Ten ewes were maintained in a semi-intensive system under natural photoperiods with access to pasture and shelter. Blood samples were collected every 2 weeks to determine plasma progesterone concentrations. The body condition score (BCS) was determined each month. There was no seasonal variation in the plasma progesterone concentration from the months of September to January, April, and May to August. In the months of February and April, the plasma hormone levels were higher than August to November. Seventy percent (7/10) of the sheep studied had short seasonal anestrus. The periods of anestrus were concentrated between the months of September and December (spring season) in 85.7 % (6/7) of the cases evaluated. In these cases, 57.1 % (4/7) also had short periods of reproductive inactivity during other months of the year. The progesterone values obtained in the spring corroborate the higher reproductive anestrus observed in this season. Higher plasma progesterone values were found in summer and autumn with reduction in the winter to lower values in the spring. No changes in the BCS during the study period were observed. Under the studied conditions, the Santa Inês sheep showed a low degree of reproductive seasonality. However, some individual ewes had seasonal anestrus during the spring. Further studies that include management techniques are needed to improve reproductive efficiency without hormone therapy in this breed under tropical conditions.
本研究旨在描述2011年9月至2012年8月间，弗卢米嫩塞低地地区（南纬22°27′45″，巴西里约热内卢）圣伊内斯羊的年度繁殖周期。10只母羊采用半集约化饲养系统，处于自然光照周期下，可自由出入牧场和羊舍。每2周采集一次血样，以测定血浆孕酮浓度。每月测定一次体况评分（BCS）。9月至1月、4月以及5月至8月期间，血浆孕酮浓度无季节性变化。2月和4月的血浆激素水平高于8月至11月。所研究的绵羊中有70%（7/10）季节性发情期较短。在评估的案例中，85.7%（6/7）的母羊发情期集中在9月至12月（春季）。在这些案例中，57.1%（4/7）的母羊在一年中的其他月份也有较短的繁殖静止期。春季测得的孕酮值证实了该季节较高的繁殖静止期。夏季和秋季血浆孕酮值较高，冬季降低，春季降至较低水平。研究期间未观察到体况评分有变化。在所研究的条件下，圣伊内斯羊表现出较低程度的繁殖季节性。然而，一些母羊在春季有季节性发情期。需要进一步开展包括管理技术在内的研究，以在热带条件下，无需激素治疗即可提高该品种的繁殖效率。
