Effects of flavonoids from Allium mongolicum Regel on growth performance and growth-related hormones in meat sheep

This study was conducted to investigate the effects of different doses of flavonoids from Allium mongolicum Regel on the production performance and neuroendocrine hormones in meat sheep and to determine the optimum dosage of Allium mongolicum Regel flavonoids to add to the basal diet of dry lot-feeding meat sheep. Sixty meat sheep (initial body weight = 39.9 ± 3.2 kg; 6-month-old) were randomly assigned to 4 groups (15 sheep per group). The sheep in the control group were fed a basal diet, and the 3 experimental groups were fed the basal diet supplemented with flavonoids at 11, 22 and 33 mg/kg. Blood samples were collected via the jugular vein at d 0, 15, 30, 45, and 60 to determine the neuroendocrine hormone levels. The fasting weight of the sheep was measured during the experimental period, and feed offered and refusals were recorded daily. The basal diet supplemented with flavonoids from 11 to 33 mg/kg significantly increased the daily weight gain and average daily feed intake (P < 0.05) and significantly decreased the feed conversion ratio (P < 0.05), but there were no differences among the supplementation groups (P > 0.05). Starting on d 30, the growth hormone (GH) and insulin-like growth factor-1 (IGF-1) levels in the sera of the sheep in the supplementation groups increased significantly (P < 0.05), and the increases occurred in a time-dependent manner. Compared with control group, after d 30, the serum corticosterone (CORT) levels were reduced in the sheep that consumed the basal diet supplemented with 22 mg/kg flavonoids (P < 0.05), but among the other experimental groups, there was a non-significant effect (P > 0.05). The serum adrenocorticotropic hormone (ACTH) levels were increased by the supplementation of flavonoids, but compared with the control group, the effect was not significant. The basal diet supplemented with flavonoids at levels from 11 to 33 mg/kg had a significant effect on the production performance and neuroendocrine hormone levels of meat sheep, and the effect occurred in a time-dependent manner. The effect was especially obvious after 30 d of feeding.