放牧补饲对草地藏系绵羊的生长性能、瘤胃发酵参数及血清生化、免疫和抗氧化指标的影响OA北大核心CSTPCD

The aim of this experiment was to determine the effects of grazing supplementation on the growth performance,rumen fermenta-tion parameters and serum biochemical,immunological and antioxidant indices in grassland Tibetan sheep.Sixty healthy Tibetan sheep weighing(23.74±2.16)kg at 7 months of age,with similar body size,were selected and randomly divided into two groups,with three repli-cates in each group and 10 sheep in each replicate.Among them,the natural grazing group grazed on the pasture all day without supplemental feeding;the grazing+supplemental feeding group grazed on the pasture all day without supplemental feeding,but supplemented with concen-trate after returning from the pasture.During the test,the two groups received the grazing management under the same conditions,grazing be-ginning at 9:00 and returning from the pasture at 17:30;and the test period was 70 d(pre-test period of 10 d,and the main test period of 60 d).The results showed as follows:The body height of the grazing+supplementary feeding group was significantly higher than that of the natural grazing group(P＜0.01);and the body weight,ADG and body length of the grazing+supplementary feeding group were significantly higher than those of the natural grazing group(P＜0.05).The pH value and acetic acid/propionic acid value of the natural grazing group were significantly higher than those of the grazing+supplementary feeding group(P＜0.01);the total volatile fatty acids,acetic acid,butyric acid,isobutyric acid and isovaleric acid of the grazing+supplementary feeding group were significantly higher than those of the grazing+sup-plementary feeding group(P＜0.01);and ammoniacal nitrogen,propionic acid,and valeric acid were significantly higher(P＜0.05)in the grazing+supplementary feeding group than those in the natural grazing group.The content of GLU in the serum of the grazing+supplementary feeding group was highly significant(P＜0.01)higher than that of the natural grazing group,and the content of IgG in the serum of the graz-ing+supplementary feeding group was significantly higher(P＜0.05)than that of the natural grazing group.The content of GSH-Px and SOD in serum of the grazing+supplemental feeding group was extremely significantly higher than those in the natural grazing group(P＜0.01),and the content of T-AOC in serum of the grazing+supplemental feeding group was significantly higher than that in the natural grazing group(P＜0.05).The serum content of MDA was significantly higher(P＜0.05)in the natural grazing group than in the grazing+supplemental feeding group.Taken together,supplemental feeding of concentrate contributed to the growth performance,rumen fermentation level,serum antioxidant capacity and immune function of grassland Tibetan sheep under grazing conditions,and improve their serum biochemical indexes.