| In this study,the effects of guanidine acetic acid supplementation on digestion,metabolism and production performance of Kazak sheep were studied,which provided a reference for the scientific utilization of guanidine acetic acid(GAA)in Kazak sheep production.Kazakh RAMS aged3 months with a body weight of(27.29±0.72)kg were used in the experiment.A total of 24 experimental sheep were randomly divided into 4 groups according to their average body weight,with 6 sheep in each group.Each sheep in each group was supplemented with 0 mg/kg GAA in the control group,500 mg/kg GAA in the Ⅰ group,1000mg/ k GAA in the experimental group and1500mg/ kg GAA in the experimental group every day,respectively.The pre-feeding period was 5days,and the formal period was 90 days.Weighing on the 1d,30 d,60d and 90 d of the test;Fecal and urine samples were collected at 26-30 d,56-60 d and 86-90 d.Blood samples were collected at60d;The sheep were slaughtered after the end of the trial period.The results showed as follows: 1)after dietary supplementation with different levels of guanidine acetic acid,the concentration of GAA in blood of Kazak sheep was significantly increased with the increase of GAA content,and the peak value was reached at 3-4 h,and the concentration of GAA in 1500mg/kg group was the highest(P<0.01).2)Digestion and metabolism: there were no significant differences in the apparent digestibility of dry matter,organic matter,crude protein,NDF,ADF,calcium and phosphorus on day 30(P>0.05).Apparent digestibility at 60 days was significantly affected by intake(P<0.01).In crude protein,the fecal protein in the control group was significantly higher than that in the Ⅰ group,the PA group and the ALN group,which were 7.12%,18.00% and 25.61% higher than those in theⅠ group(P<0.01).The crude protein digestibility in Ⅲ group was 12.85%,10.87% and 3.81% higher than that in the control group,the extracts group and the extracts group,respectively(P<0.01).The digestibility of crude protein in Ⅲ group was 12.88%,9.25% and 3.23% higher than that in control group,Alba group and Alba group,respectively(P<0.01).In NDF,the digestible amount was decreased by 9.17% compared with the control group(P<0.05).ADF in feces in control group was3.64%,14.78 and 14.91% higher than that in Ⅰ group,prune group and aniseed group,respectively(P<0.05).The digestibility of ADF in Ⅱ group and test group was 5.09% and 6.85% higher than that in control group(P<0.05).After 90 days,the ADF in feces in the control group was 20.44% higher than that in the Ⅰ group(P<0.05).Dietary supplementation of guanidine acetic acid at different levels had no significant effects on metabolism,calcium metabolism,phosphorus metabolism and nitrogen metabolism of Kazak sheep at 30 days(P>0.05).On day 60,compared with the control group,the intake of nitrogen in feces decreased,and the nitrogen in feces in the control group was 7.11%,18.06% and 25.59% higher than that in the Ⅰ group,the Fe group and the N group(P<0.01).The retention of calcium in Ⅲ group was 14.05%,20% and 9.96% higher than that in control group,fat group and fat group,respectively(P>0.05).At 90 d,there were no significant effects on nitrogen metabolism,calcium metabolism and phosphorus metabolism(P>0.05).3)Compared with the control group,the body weight gain from day 1 to 60 was increased by 17.83%(P<0.05);Compared with the control group,the feed/gain on 1-60 days was decreased by 19.41%(P<0.05).4)Compared with the control group,carcass weight and slaughter percentage also showed a decreasing trend linearly(P<0.05).In conclusion,dietary supplementation of 1500 mg/kg GAA can improve the content of guanidine acetic acid and its metabolites in blood,digestive performance,production performance and slaughter performance of Kazak sheep.In this experiment,the appropriate supplemental level of GAA in the diet was 1500 mg/kg. |
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