| Astragalus polysaccharide(APS)is one of the main active components of Astragalus membranaceus.It is a kind of macromolecular compound which plays a decisive role in the pharmacological action of Astragalus membranaceus.Astragalus membranaceus polysaccharide can effectively enhance immunity,anti-oxidation,antistress,anti-virus,anti-tumor,anti-aging and regulate blood sugar and so on.Astragalus polysaccharide has been widely used in animal production because of its safety,nutrition,small toxicity and side effects,and has enhanced the immunity and anti-oxidation ability of animal body.At present,there are more reports on the application of astragalus polysaccharides in pigs and poultry,but few on ruminants.In this experiment,healthy newborn Holstein calves were used to feed astragalus polysaccharide in order to study the effects of different levels of astragalus polysaccharide on the growth performance,immune performance and antioxidant activity of calves,and the effects of different levels of astragalus polysaccharide on the growth performance,immune performance and antioxidant activity of calves were studied.It provides a theoretical basis for the rational application of astragalus polysaccharide in calf production practice.According to the birth weight of 40 ±5 kg of calf and 35 ±5 kg of female calf,60 healthy newborn Holstein calves were screened out according to the criterion that the serum total protein(total protein,TP)of calves was higher than that of 5.5g/dl 24 hours after birth.Randomized block design was used in the study.The calves of the same sex were divided into three groups: control group,trial group A,trial group B,trial group C,each group having 15 repeats,the same age group was born on the same day,and the calves of the same sex were divided into control group,test group A,trial group B,trial group C.One cow per repetition.The control group was fed with basal diet,experiment A,B,C were treated with astragalus polysaccharide,and the basal diet was supplemented with 100g/t,200g/t,300g/t and the other three groups were treated with Astragalus membranaceus polysaccharide(APS).The experimental period was 2-56 days old.Experiment 1: To study the effect of astragalus polysaccharides on the performance of calves was studied.The daily intake of calves and the body weight and body size(body height,body length,chest circumference,chest depth,anterior tube circumference and abdominal circumference)measured every Sunday were recorded.Experiment 2: To study the effect of astragalus polysaccharides on calf immune performance,research record calf disease prevalence(diarrhea,pneumonia,etc.).The blood samples were collected by vacuum tube jugular vein puncture before morning feeding at the age of 0,2,4,6 and 8 weeks,respectively.The contents of blood serum total protein(TP),albumin(ALB),globulin(GLB),total cholesterol(CHO),the content of urea nitrogen(BUN)in blood were determined.Experiment 3: To study the effect of astragalus polysaccharides on the antioxidant capacity of calves,the blood samples were collected by vacuum tube jugular vein puncture before morning feeding at the age of 0,2,4,6 and 8 weeks,respectively.The contents of malondialdehyde(MDA),total antioxidant capacity(T-AOC),glutathione peroxidase(GSH-Px)and superoxide dismutase(SOD)in blood were determined.The results are as follows:1.Effects of different levels of astragalus polysaccharide on production performance of calves.The results showed that compared with the control group,the weight of the experimental group increased by 6.7%,4.1% and 4.7% respectively,but the difference was not significant(P>0.05),and the difference of the feed intake between the experimental group and the control group was not significant(P>0.05).The ratio of feed to weight in test group was lower than that in control group(P>0.05),and the body height in test group A and C was significantly higher than that in control group(P<0.05)at the age of second week.At the age of 4 weeks,the chest depth of test group A was significantly higher than that of test C and B groups(P<0.05),but there was no significant difference among other groups(P>0.05).At the age of 7 weeks,the chest depth of group A was significantly higher than that of control group(P<0.05),but there was no significant difference among the other groups(P>0.05).Compared with the control group,the body oblique length and chest circumference of the experimental group showed an increasing trend(P>0.05),but there was no significant difference in the anterior tube circumference and abdominal circumference between the experimental group and the control group(P>0.05).2.Effects of different levels of astragalus polysaccharides on the immune performance of calvesThe results showed that the diarrhea rate in the control group was higher than that in the control group,the highest was 9.17% in the control group,the lowest was 6.9% in group B,the next was test A and group C.At the end of the experiment,the serum total protein(TP)in the control group was significantly lower than that in the B,C group(P<0.05),and the serum albumin(ALB),total cholesterol(CHO)in the control group was significantly lower than that in the test group(P<0.05).The serum globulin(GLB)in control group was lower than that in experimental group(P>0.05),and the serum urea nitrogen(BUN)in control group was higher than that in experimental group(P>0.05).3.Effects of different levels of astragalus polysaccharides on antioxidation ability of calves.The results showed that at the age of 1 week,the serum malondialdehyde(MDA)in group B was significantly lower than that in group A(P<0.05),and the serum malondialdehyde(MDA)in group C was significantly lower than that in control group and other groups at 2 weeks(P<0.05).At the age of 8 weeks,the serum total antioxidant capacity(T-AOC)of the experimental group A was significantly higher than that of the experimental group C(P<0.05),and the serum glutathione peroxidase(GSH-PX)of the test group C was significantly higher than that of the control group and the other two groups(P<0.05).Before 4 weeks,the serum superoxide dismutase(SOD)in the test group had A tendency to increase.According to the above results,the addition of astragalus polysaccharide can promote the growth of calves to a certain extent,enhance the immunity of lactating calves,improve the resistance,and reduce the incidence of common diseases such as diarrhea and pneumonia in lactating calves.Astragalus polysaccharide has good antioxidant ability and can prevent oxidative free radical damage to some extent. |
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