Comparison Of Intestinal Nutrient Transporters And Intestinal Microflora Between Quality Meat-Type Chicken And Fast-Growing Broiler

Compared with the fast-growing broiler,the quality meat-type broiler has the characteristics of good meat quality and flavor,strong stress resistance,but the growth rate is relatively slow.The small intestine is the main organ for nutrient digestion and absorption.After entering the intestine,the nutrients in the diet are digested by microorganisms and a variety of digestive enzymes.More than 80%of the chicken’s food digestion is completed in the intestine,and 99%of the nutrients are absorbed by the intestine.Therefore,in order to improve the efficiency of intestinal digestion and utilization of nutrients and promote the growth of Tianfu broilers,500Ross 308 fast-growing white broilers and 500 Tianfu broilers of commercial generation hatched in the same batch were selected and raised in the same environment until the age of 6 weeks.The growth performance,blood antioxidant capacity index,intestinal nutrient transporter expression,intestinal morphology,and the structure and species of intestinal microbial flora of the two varieties were compared and analyzed.The main results are as follows:（1）Body weight and feed conversion calculations showed that:The average daily gain,average daily feed intake,relative growth rate and feed to meat ratio of Ross 308 broilers were60 g/d,88 g/d,1.8,and 1.42,respectively,which were 2 times（30 g/d）,1.3 times（68 g/d）,1.1times（1.62）and 0.67 times（2.12）of Tianfu broilers.（2）Measurement of serum biochemical indicators showed that:The catalase（CAT）content of Tianfu broilers was significantly lower than that of Ross 308 broilers（P<0.05）;In the first week,the content of glutathione peroxidase（GSH-Px）of Tianfu broilers was significantly lower than that of Ross 308 broilers（P<0.05）;The malondialdehyde（MDA）content of Tianfu broilers was significantly lower than that of Ross 308 broilers（P<0.05）;Superoxide dismutase（SOD）and total antioxidant capacity（T-AOC）were not significantly different at several time points（P>0.05）,but T-AOC content increased with the increase of age（P<0.01）.The antioxidant stress capacity of Tianfu broilers was slightly lower than that of Ross 308 broilers,but the self antioxidant stress capacity increased significantly over time.（3）Intestinal morphological examination revealed:The intestinal villus height（VH）and crypt depth（CD）of Ross 308 broilers were lower than those of Tianfu broilers（P<0.05）,but there was no significant difference in the cashmere/cryptogenic ratio（V/C）（P>0.05）.By the 6th week,the VH of Ross 308 broilers was significantly higher than that of Tianfu broilers（P<0.01）.The velvet and hidden ratio of Ross 308 broilers was higher than Tianfu broilers（P<0.05）;The jejunal VH and CD of Ross 308 broilers were smaller than those of Tianfu broilers as a whole,and there were significant differences in VH,CD and V/C of Ross 308 broilers at the third week（P<0.01）;The ileal VH and CD of Ross 308 broilers were higher than those of Tianfu broilers,but the V/C of Ross 308 broilers was significantly higher than that of Tianfu broilers at the 5th and 6th week（P<0.05）.The intestinal development capacity of Tianfu broilers was weaker than that of Ross 308 broilers.（4）Relative abundance of microbial species in ileum and cecum:The top10 dominant bacteria in the ileum and cecum of Romboutsia,Clostridia＿UGG＿014,Clostridia＿sensu＿stricto＿1,Alistipes,Gastranaerophilales,Barnesiella,Bacteroides,Lactobacillus,Staphylococcus and Escherichia-Shigella.In the fifth and sixth week when the daily weight gain of Ross 308 broilers was the largest,the content of Lactobacillus in the ileum increased（42.5%,48%）,while the content of Lactobacillus in the ileum of Tianfu broilers was less（13%）.（5）16s rRNA gene sequencing of ileum and cecum microorganisms:chao1,shannon and simpson index box plots all showed that the cecum flora structure of Ross 308 broilers was more abundant than that of Tianfu broilers,with higher polymorphism（P<0.05）,with greater fluctuation of community species.The number of OTUs in the intestines of Ross 308 broilers was significantly higher than that of Tianfu broilers（P<0.05）,with the highest number of OTUs in the cecum of Ross 308 broilers（P<0.01）.Beta diversity analysis（PCo A,PCA and NMDS）showed that there was a small difference in the microbial community composition of ileum and Tianfu broilers,but a large difference in the microbial community composition of cecum and Tianfu broilers.The composition of the cecum and Tianfu ileum of Ross 308 broilers was different.（6）Ileal metagenomic analysis:LEf Se analysis showed that Syncephalastraceae and Mucorales were the most important microbial groups in the ileum of Ross 308 brocers.The differential markers in the ileum of Tianfu broilers and the microbial groups that played an important role were Dietziaceae and Lactobacillales.（7）Intestinal nutrient transporters:genes with significant differences of three weeks or more were selected for analysis.In the duodenum,EAAT3 in Tianfu broilers was significantly lower than that in Ross 308 broilers at the 5th and 6th weeks（P<0.05）;The expression of GLUT2 was low in the intestine of Tianfu broilers at the second and third weeks（P<0.05）;At week 1,5 and6,the expression level of CAT2 in the intestinal tract of Tianfu broilers was significantly lower than that of Ross 308 broilers（P<0.01）;The expression of B^oAT in the intestinal tract of Tianfu broilers was lower than that of Ross 308 broilers（P<0.05）.In jejunum,the expression level of CAT2 in Tianfu broilers was lower than that in Ross 308 broilers（P<0.01）.In ileum,the expression levels of EAAT3 and b^o,+AT in Tianfu broilers at 3rd and 5th weeks were lower than those in Ross 308 broilers（P<0.05）;GLUT5 expression was low in Tianfu broilers at 3,5 and 6weeks（P<0.01）.In cecum,SGLT1 expression of Tianfu broilers was significantly lower at 1,2and 5 weeks（P<0.05）;The expression of b^o,+AT in Tianfu broilers was significantly lower than that in Ross 308 broilers at the 3rd and 6th weeks（P<0.05）.In conclusion,Ross 308 broilers were superior to Tianfu broilers in terms of growth performance and antioxidant capacity.There were great differences in the structure of ileal and cecum microbiota between the two kinds of broilers,and the intestinal microbial community of Ross 308 broilers was more abundant.Lactobacillus,Bacteroides and Barnesella are the dominant bacteria that can enhance the body’s immunity,promote nutrient digestion and absorption and provide energy source.The expressions of EAAT3,GLUT2,GLUT5,CAT2,Bo AT,bo,+AT and SGLT1 in Ross 308 broilers are significantly higher than those in Tianfu broilers,which can provide theoretical basis for molecular breeding to improve the growth performance of Tianfu broilers...