A calm temperament in ewes improves ovulation rate and successful pregnancies, according to a study published by The University of Western Australia (UWA).

The study, which was conducted in collaboration with researchers from Uruguay, Western Australia's Department of Primary Industries & Regional Development and UWA, has implications for the impact stress has on reproduction in humans, as well as cows, sows and other farmed livestock.

The team investigated the reproductive outcomes of 200 Merino ewes known to have either a calm or a nervous temperament. They found the ovulation rate and rate of successful pregnancies to be higher in the calm ewes, according to an announcement.

Associate professor Dominique Blache from the UWA School of Agriculture & Environment and Institute of Agriculture, who led the study, said temperament does not affect the occurrence of ovulation, but it affects ovulation rate.

“Differences in reproductive outcomes between the calm and nervous ewes were mainly due to a higher ovulation rate in calm ewes,” Blache said. “Even when the ovulation rate is maintained, some of the nervous ewes have problems maintaining their pregnancy, possibly because of the quality of the eggs and subsequent embryos and perhaps the quality of the uterine environment during the first two weeks of pregnancy.”

The results also suggest that reproduction in nervous ewes is compromised by factors leading up to ovulation and conception or in the uterine environment during early pregnancy that reflect differences in energy utilization, UWA said, adding that understanding why the reproductive outcome of these ewes is different will help breed sheep better suited to a particular production system, improving their welfare.

The paper, "Calm Merino Ewes Have a Higher Ovulation Rate & More Multiple Pregnancies Than Nervous Ewes," was published in the journal Animal, and the research was supported by Meat & Livestock Australia.