EFFECT OF FOCUSED FLUSHING AT THE END OF THE ANTICIPATED NORMAL LUTEAL PHASE ON SYNCHRONIZATION OF OESTRUS BY INTRODUCTION OF RAM IN THE FLOCK

N. Todorov, М. Simeonov, K. Nedelkov

Abstract: The purpose of this study was: 1) to determine the influence of short-time high nutrient intake focused in second part of luteal phase over the response of ewes to the synchronizing oestrus effect of the ram; 2) to determine the effect of a complex of factors known that could influence on the “ram effect”. The experiment has been carried out with 344 Pleven Blackhead ewes, divided into two groups. The first group of 168 ewes with average BCS 3.5 and mean live body weight of 66.7 kg, served as a control. The second group of 176 ewes with average BCS 3.2 and mean live body weight of 63.2 kg was put on an intensive short time feeding. Ewes from both groups received 300 g barley per day while the experimental group received an additional 400 g of soybean screenings. In this way, it was investigated whether the lower BCS could be compensated by short-time abundant feeding. The experiment was conducted in the beginning of the natural breeding season of ewes. The artificial insemination started at 06.08.2011. It was observed a delay in the onset of oestrus with two days at the focused (acute) flushed ewes compared with the control group. Perhaps the difference could be associated with the different body condition of groups and with the applied intensive feeding to the experimental group, which may have influenced the lifespan of the last non-ovulatory and ovulatory follicles. Within 11 days, which coincided with the two peaks induced by the “ram effect”, ewes in oestrus were 72.0% of all sheep in the control group or 80.1% of all lambed ewes. In addition, at the experimental group the respective indexes are 76.1% and 83.8%. Therefore, with a proper implication of the oestrus synchronization by the “ram effect” it could be achieved 80.1% to 83.8% of inseminated ewes within 11 days. Despite some differences in BCS and live weight between the two groups, it was not found differences in the biological fecundity of ewes.

Keywords: ewes; focused flushing; luteal phase; oestrus synchronization; ram effect

Date published: 2019-01-28