| In order to explore the importance of early nutrition regulation in broilers,soy protein concentrate was added to starter diet(1-10 d)to investigate its effects on growth performance,amino acid apparent digestibility,intestinal development,intestinal microorganisms and metabolites of broilers.It could be provided a new knowledge for broiler early nutrition regulation,and also provide technical support for the application of soy protein concentrate in broiler production.A total of 832 1-day-old AA broilers with similar body weight(46.05± 0.37 g)were randomly divided into 4 groups with 8 replicates in each group and 26 broilers in each replicate.The experiment was divided into three phases: 0%(control),4%(SPC4),8%(SPC8)and 12%(SPC12)of soy protein concentrate were added to the diet at the early stage of birth(1-10 d),and then the same basal diet was fed at the growth stage(11-21 d)and the fattening stage(22-42 d)for 42 days.During the whole experiment,the birds were fed and drank freely.The results showed that:(1)The effects of soy protein concentrate on the performance of broilers were as follows: The results of growth performance showed that compared with the control group,the body weight and average daily gain of SPC12 group increased significantly at 10 d(P<0.05),and the average daily feed intake of SPC8 and SPC12 groups increased significantly at 1-10 d(P<0.05).At 42 d,compared with the control group,the body weight of SPC8 and SPC12 increased significantly(P<0.05),and the average daily gain of 1-42 d in SPC8 and SPC12 groups increased significantly(P<0.05).The results of blood biochemical indices showed that the total cholesterol content of SPC12 group was significantly higher than that of the control group at 42 d(P<0.05).The results of carcass traits showed that compared with the control group,the carcass yield and the thymus indices were significantly increased in the SPC12 group of broilers at 42 d(P<0.05).The results of meat quality showed that dietary soy protein concentrate had no significant effect on meat quality of 42 d broilers(P>0.05).(2)The effect of soybean protein concentration on apparent digestibility of broilers was studied as follows: The results of acid binding capacity showed that the p H value and ABC-4 value were significantly decreased in starter diet(1-10 d)(P<0.05),and the p H value and ABC-4value of broiler diets were gradually decreased with the increase of soy protein concentrate.At the same time,compared with the control group,the ABC-3 in SPC8 and SPC12 groups were significantly decreased(P<0.05).The results of pancreatic enzyme activity showed that there was no significant difference of broilers(P>0.05).The results of amino acid apparent digestibility showed that compared with the control group,the apparent digestibility of isoleucine in SPC8 group was significantly lower(P<0.05),and the apparent digestibility of leucine and phenylalanine in SPC4 and SPC8 groups was significantly lower(P<0.05).In addition,the apparent digestibility of other amino acids was not significantly affected by soy protein concentrate(P>0.05).(3)The effect of soybean protein concentration on digestive tract development of broilers was studied as follows: The results of intestinal development showed that the absolute weight of ileum gradually increased with the increase of soy protein concentrate at 10 d(P<0.05),but there was no significant difference with control group(P>0.05).Compared with the control group,the absolute weight of gizzard in SPC8 and SPC12 groups increased significantly(P<0.05),the relative weight and length of jejunum in SPC4,SPC8 and SPC12 groups decreased significantly(P<0.05),and the relative length of ileum in SPC4 and SPC8 groups decreased significantly(P<0.05).At 42 d,compared with the control group,there is no significant effect on the intestinal development of broilers(P>0.05).The results of intestinal mucosal morphology showed that compared with the control group,at 10 d,the villus height of jejunum in SPC12 group increased significantly(P<0.05),the muscle thickness of ileum in SPC 8and SPC 12 groups increased significantly(P<0.05),and the ratio of villus height to crypt depth in SPC4 group increased significantly(P<0.05).At42 d,compared with the control group,the villi height of ileum in SPC4 and SPC8 groups decreased significantly(P<0.05),and villi height and crypt depth of ileum in SPC4,SPC8 and SPC12 groups were significantly decreased(P<0.05).The results of goblet cells showed that the number of goblet cells in duodenum of SPC8 and SPC12 groups increased significantly compared with the control group at 10 d(P<0.05).However,there is no significant effect in jejunum and ileum at 10 d and small intestine at 42 d(P>0.05).(4)The effect of soybean protein concentration on intestinal microflora and its metabolites of broilers was studied as follows: The results of OTU composition,species richness analysis,Alpha diversity index and Beta diversity index showed that,compared with the control group,the composition and relative abundance of intestinal microorganisms of broilers at 10 and 42 d were changed to a certain extent by soy protein concentrate.The results of different intestinal microflora showed that,at 10 d,compared with the control group,the relative abundance of Negativibacillus,Papillibacter,Lachnospira,Proteus and Dietzia in SPC8 group increased significantly(P<0.05),while the relative abundance of Intestinimonas,Negativibacillus,Flavonifractor,Ruminiclostridium,Hydrogenoanaerobacterium,unidentified＿Lachnospiraceae,Shuttleworthia,Sellimonas,Erysipelatoclostridium and Proteus in SPC12 group increased significantly(P<0.05).At 42 d,compared with the control group,the relative abundance of unidentified＿Ruminococcaceae in SPC8 group was increased significantly(P<0.05),and the relative abundance of unidentified＿Ruminococcaceae and Erysipelatoclostridium in SPC12 group was increased significantly(P<0.05).The results of short chain fatty acids in cecum showed that,compared with the control group,the contents of butyric acid and total butyric acid in SPC8 and SPC12 groups were significantly increased at 10 d(P<0.05).In conclusion,12% soy protein concentrate in broiler starter growth diet significantly improved the starter and whole growth performance,promoted the early intestinal development,increased the number of intestinal beneficial bacteria and butyric acid content of broilers.The results showed that the early growth of broilers was regulated by 12% soy protein concentrate to the starter diet for better performance. |
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