| Popis: |
Background:In this study, we investigated the effects of cotton (Gossypium spp) stubble grazing during winter on the feed intake, grazing behavior, and blood chemical parameters of Altay ewes in Xinjiang, China. Eighty adult and twenty-five young ewes grazed continuously on cotton stubble from sunrise to sunset for 90 d during the winter, without receiving any supplementary feed. We measured the biomass and components of cotton stubble before, and at 1 and 2 months of grazing; the ewes’ feed intake and grazing behavior at 1 and 2 months; and their blood parameters and immunity indices at the beginning and end of the grazing period. Results: The biomass of cotton stalk was 5486.08 kg/hm2 at the beginning and decreased to 4340.90 ± 917.10 kg/hm2 and 3599.09 ± 689.56 kg/hm2 at 1 and 2 months, respectively. The proportion of cotton leaves and boll shells in each component of cotton stalk decreased significantly (P < 0.05). At 1 and 2 months, the walking time of ewes was 93.58 ± 3.08 min and 115.99 ± 2.25 min and the distance covered was 6.8 ±0.92 km and 10.2 ± 2.30 km, respectively; both increased significantly during the late grazing stage (P < 0.05). At 1 and 2 months, the feed intake and dry matter digestibility did not differ significantly (P > 0.05). The intake of digestible energy and digestible crude protein levels at 1 and 2 months in sheep were 7.91~9.58 MJ/d and 47.30~69.04 g/d, respectively, which were lower than the nutritional requirements of grazing ewes. Compared with those before grazing, the blood platelet count and iron concentration in ewes at the end of grazing decreased significantly (P < 0.05), whereas the concentrations of free gossypol and aspartate aminotransferase significantly increased (P < 0.05). The most common activity of the ewe’s day was grazing, the grazing time of ewes accounted for over 60 % of the total pasture time. Conclusion:Owing to the limited feed intake and digestibility of cotton stubble in winter, the demand for digestible energy and digestible crude protein in ewes cannot be satisfied by grazing alone. |
