Effect Of β-Alanine On Growth Performance,Meat Quality And Muscle-Derived Active Peptide

β-alanine,a precursor involved in the formation of carnosine and anserine but not participate in the biosynthesis of protein,has been widely used as a nutritional supplement to strength muscle endurance in sport medicine field nowadays.It was reported thatβ-alanine could increase the growth performance,improve the meat quality through regulating the growth rate of muscle and elevation the content of muscle-derived active peptide.Therefore,determination of the optimum dosage in broilers’diets and explorement of the possible mechanism of carnosine synthesis by addingβ-alanine in the broiler chicken is valuable for its application in broiler industry.The current student consisted of 3experiments.Experiment 1.Effect ofβ-alanine on growth performance and slaughtering performance.The objective of the current study was to investigate the effect of dietaryβ-alanine supplementation on growth performance and slaughtering performance,therefore starting to explore the effect ofβ-alanine in broilers.A total of 240 1-d-old Arbor Acres broilers were randomly assigned into four dietary treatments supplemented with 0（control group）,200（βA2 group）,400（βA4 group）or 600mg/kg（βA6 group）ofβ-alanine.Each treatment included six replicates（cages）of 10 birds.The feeding trial lasted for 42 days,including the starter period（1²1d）and the grower period（22⁴2d）.The results showed as follows:1)The body weight of 42 d and average daily gain of grower period were significantly increased when adding with 600 mg/kgβ-alanine（P<0.05）,the ratio of feed to gain was markedly reduced ofβA6 group during the whole period,but there are no difference in average daily feed intake and mortality among all groups（P>0.05）.2)Compared with the control group,carcass traits including dress percentage,leg muscle percentage and abdominal fat percentage have no significant differences among all groups（P>0.05）,breast muscle percentage in chicks fed 600 mg/kg significantly increased by 12.27%and in chicks fed 400 mg/kg increased by 3.21%.In conclusion,dietary withβ-alanine could increase body weight and average daily gain without adversely affecting daily feed intake,and improve the growth of breast muscle,especiallyβA6 group.Experiment 2.Effect ofβ-alanine on growth performance,meat quality,carnosine content in broilersThis experiment was conducted to study the supplementation of different levels ofβ-alanine on growth performance,meat quality,carnosine content in broilers.A total of 360 one-day-old Arbor Acres male broilers were randomly allotted into 6 groups with 6 replicates of 10 broilers each.The control group was fed a basal diet,the other five groups were fed a basal diet supplemented with 250（βA2.5 group）,500（βA5 group）,750（βA7.5 group）,1 000 mg/kgβ-alanine（βA10 group）.The results showed as follows:1)Compared with the control group,the body weight was significantly increased at21 days of age（P<0.05）,and numerically increased about 21⁷2 g at 42 days of age when adding with500 mg/kgβ-alanine（P>0.05）,average daily gain of bothβA5 andβA10 group had increase trends during the growth period and the whole period（0.05<P<0.1）;the ratio of feed to gain ofβA5 groups had decreased during the start period,the growth period,the whole periodespecially the first period and whole period（P<0.05）;2)Compared with the control group,dripping loss of breast muscle inβA5 was significantly decreased（P<0.05）,and the value of a*of breast muscle inβA5 group was significantly increased（P<0.05）;3)Compared with the control group,the content of MDA of breast muscle had decreased trends with adding 500 mg/kgβ-alanine.after slaughtering 2 days（P=0.077）and 4 days（P=0.062）,and the content of MDA of breast muscle in broilers was significantly decreased 6 days after slaughtering when theβ-alanine was added 500,750,1 000 mg/kg（P<0.05）.4)Compared with the control group,the content of carnosine of breast muscle was significantly increased in broilers（P<0.05）,increased form 14.4%to 19.5%in allβA groups.Therefore,the supplementation of 500 mg/kgβ-alanine in the diet in broilers can promote the growth performance,decrease the drip loss and the content of MDA on breast muscle,increase the content of functional carnosine of breast muscle,improve the meat quality.Experiment 3.Effect of dietaryβ-alanine supplementation on meat quality,carnosine content and synthesis-related enzyme expression in broilersThe objective of the current study was to investigate the effect of dietaryβ-alanine supplementation on meat quality,carnosine content and gene expression of carnosine-related enzymes,therefore confirming the optimum dosage ofβ-alanine in broilers.A total of 540 1-d-old male Arbor Acres broilers were randomly assigned into five dietary treatments supplemented with 0（control group）,250,500,1000 or 2000 mg/kg ofβ-alanine.Each treatment included six replicates（cages）of 18 birds.The feeding trial lasted for 42 days.Birds fed a diet contain 500 mg/kg showed higher average daily gain compared with those fed the control diet in the starter（d 1 to 21）and whole period（d 1 to 42）（P<0.001 and P=0.036,respectively）,the feed conversion ratio（F/G）decreased quadratically in response to dietaryβ-alanine supplementation during the starter and whole period（P<0.001 and P=0.003,respectively）.In grower period（d 22 to 42）,FCR tended to decrease with dietaryβ-alanine addition（P=0.064）.The concentrations of carnosine andβ-alanine in breast muscle（d 42）increased quadratically（P<0.001 and P=0.001）with the increasing of dietary supplementation ofβ-alanine.Chicks fed theβ-alanine-added diet showed the lower taurine concentration in plasma（P=0.001）.In addition,meat taurine concentration tended to decrease with dietaryβ-alanine supplementation（P=0.079）.Compared to the control group,chicks inβ-alanine-added groups had higher breast muscle yield（d 21,P=0.023）.Dietary supplementation of 1 000 mg/kgβ-alanine resulted in lower meat shear force（P=0.033）,whereas a*_{45 min} and a*_{24 h} value increased quadratically in response to dietaryβ-alanine addition of 500 mg/kg（P=0.020 and P=0.021）.Dietaryβ-alanine addition significantly enhanced the gene expression of carnosine synthase and taurine transporter（P<0.05）.In conclusion,dietaryβ-alanine supplementation improved growth performance and carnosine content,ameliorated antioxidant capacity and meat quality,upregulated the gene expression of carnosine synthesis-related enzymes in broilers.Overall,dietary 500¹ 000 mg/kgβ-alanine supplementation improved average daily gain,growth performance and carnosine content,ameliorated antioxidant capacity and meat quality,upregulated the gene expression of carnosine synthesis-related enzymes in broilers.