Behavioral and physiological difference of small-tailed Han sheep at different estrus stage after delivery

This study aimed to analyze the changing behavior and physiological hormones at different postpartum stage of small-tailed Han sheep with different postpartum intervals. Ten ewes with single birth and similar body conditions were selected, and all ewes were naturally pregnant and remained with their lambs until weaning. Based on the length of the post-partum interval, these ewes were divided into two groups, namely, group I (45 ± 7 days) and II (65 ± 7 days). The interval from delivery to re-estrus was divided into three stages, namely, S1 (first 10 days after delivery), S2 (middle 10 days during the interval), and S3 (last 10 days before re-estrus). The behavior was observed with the Observer XT system by scan sampling, and the fecal hormones were detected by EIA. Based on the results, more standing and observing were observed in group I than that in group II. In group II, compared with stage 2 and 3, the ewes had significant more sucking at stage 1. The relaxing and ruminating in both groups and the other behaviors except for foraging in group II had significant changes during the interval from delivery to re-estrus (P < 0.05). More fecal MLT was observed in group I than in group II after parturition (P < 0.05). Based on these results, we provide recommendations for the adequate management practices of postpartum re-estrus and breeding of the small-tailed Han sheep.