Effects Of Keratinaes Addition To Corn-soybean-feather Meal Diets On The Performance Of Broiler Chicken

The shortage of feed resources is an insurmountable global problem.Due to the large population in China,there is a problem of"food competition between humans and animals",which leads to the shortage of protein feed resources in the context of trade war is more serious.In order to prevent the shortage of protein feed resources rely too much on imports,can choose to develop non-conventional feed resources,improve the utilization rate of resources to fill the protein feed gap.The crude protein content of feather meal is more than 80%,but the digestibility is low due to the high amount of keratin in it.Keratinase can effectively degrade keratin and improve the digestibility of feather meal for its better application in livestock production.The objective of this study was to evaluate the effect of keratinase addition to the diet on the performance of broiler chickens fed a diet containing feather meal.One hundred and sixty-two 1-day-old Cobb 500 broiler chicks in good health and of similar body weight were randomly divided into three groups of nine replicates each,with six chicks in each replicate.The control group was fed a corn-soy-feather meal basal diet and the two treatment groups were supplemented with 100,000 and 200,000 U/kg of keratinase on top of the control diet,respectively.The main results of the experiment were as follows.1.Effect of keratinase on broiler growth performance:The addition of 200,000 U/kg of keratinase to the broiler corn-soy-feather meal basal diet significantly increased body weight gain(3.6-4.3%)and reduced the feed to meat ratio(2.4-5.6%)at 22-42 days of age and 1-42 days of age compared to the control group(P<0.05).The addition of100,000 U/kg keratinase had no effect on broiler performance(P>0.05).2.Effect of keratinase on carcass traits and serum biochemistry of broiler chickens:The addition of 100,000 U/kg or 200,000 U/kg of keratinase had no significant effect on carcass traits(slaughter rate,half-clean bore,full clean bore,pectoral muscle rate,leg muscle rate,feather weight)and serum biochemistry(ALT,AST,ALP,TP,ALB,BUN,CREA)compared with the control group(P>0.05).P>0.05).3.Effect of keratinase on apparent metabolic rate of nutrients:The addition of 200,000U/kg keratinase significantly increased the metabolic rate of ash(45.0%)and calcium(8.8%)compared to the control group(P<0.05).The addition of 100,000 U/kg keratinase had no effect on broiler production performance(P>0.05).4.Effect of keratinase on broiler muscle quality:Compared with the control group,the addition of 200,000 U/kg keratinase significantly increased the muscle p H at 45 min of slaughter by 1.6%(P<0.05),while decreasing the L~*value by 13.6%(P<0.05).It also reduced the drip loss of muscle at 24 h after slaughter by 22.1%(P<0.05).In addition,the addition of 100,000 U/kg of keratinase reduced muscle L~*values by 19.2%and drip loss by 29.2%at 24 h after slaughter compared to the control group(P<0.05).5.Effect of keratinase on the redox status of broiler pectoral muscle:Compared with the control group,the addition of 100,000 U/kg and 200,000 U/kg of keratinase to the diet significantly increased pectoral muscle GPX activity by 82.5%and 87.5%(P<0.05)and significantly decreased pectoral muscle MDA concentration by 18.3%and 14.5%,respectively(P<0.05).In conclusion,the addition of 200,000 U/kg of keratinase to a base diet containing corn-soy-feather meal improved growth performance,meat quality,apparent digestibility of nutrients and redox status of broilers.