Effect of cotton stubble grazing on the reproductive performance and blood biochemicals of ewes

This study was conducted to determine the effects of cotton-stubble grazing on the reproductive performance, blood biochemicals, and free gossypol content of ewes. The results showed that the above-ground biomass of the cotton stubble was 6 178.6 kg·ha-1, and the proportion of edible parts was more than 65%. The average daily dry-matter intake of the ewes from the cotton stubble was 1.98 kg·(d·head)-1. Compared to the indoor feeding group, birth weight of lamb were lower than feeding group, mortality reached 12.87%, reproduction rate reduced (P<0.05). The concentration of free gossypol in the serum increased with the increase in grazing time; at the end of grazing, the concentration of free gossypol in the serum was 131.70 mg·L-1, which was significantly higher than that of the feeding group (P<0.05). The white blood cell was significantly higher than feeding group (P<0.05). The blood platelet levels, serum concentrations of total proteins and magnesium in the grazing group were significantly lower than in the feeding group (P<0.05). The serum concentrations of total proteins and magnesium were slightly higher in the grazing group than in the feeding group (P<0.05). Cotton stubble is used for grazing in the winter in Xinjiang. Grazing on cotton stubble can reduce the feeding cost of the ewes, but it affects their ability to reproduce. To consider the reproductive performance and health of ewes, we suggest appropriate supplementary feeding when the ewes graze on cotton stubble.