Effects Of Dietary Energy And Protein Levels On Growth Performance,Slaughter Performance And Serum Biochemical Indices Of Hotan Black Chickens During Growing Period

This experiment was conducted to investigate the effects of different dietary Energy and protein levels on performance,slaughter performance,meat quality and serum biochemical indices of growing Hotan black chickens,and to provide theoretical basis for scientific feeding of Hotan Black chickens.A two-factor experimental design was used in the experiment.The dietary Energy and protein levels from 8 to 13 weeks of age were 11.09 MJ/kg,11.51 MJ/kg,11.92 MJ/kg and 16.50%,18.00%,19.50%,respectively.The dietary Energy and protein levels of14 to 17 weeks of age were 12.13 MJ/kg,12.34 MJ/kg,12.55 MJ/kg and 14%,15%,16%,respectively.A total of 270 42-day-old Hotan black chickens were randomly divided into 9groups with 3 replicates per group and 10 chickens per replicate.The trial test period lasted for7 days and the formal trial period lasted for 70 days.The results showed as follows :(1)Dietary energy level had extremely significant effects on daily feed intake and serum blood glucose content of Hotan Black chickens aged from 8 to13 weeks(P<0.01),leg muscle percentage and serum total cholesterol content of hens(P<0.05).Dietary protein level and the interaction between dietary energy and protein had significant influence on the evisceration rate(P<0.05).The interaction of dietary energy and protein had significant effects on serum albumin content(P<0.05),and had extremely significant effects on slaughter rate(P<0.01).Dietary energy and protein levels had extremely significant(P<0.01)or significant(P<0.05)effects on average daily feed intake,half-eviscerated percentage and abdominal fat percentage,and had extremely significant(P<0.01)effects on slaughter percentage and eviscerated percentage.The ratio of feed to gain and leg muscle percentage were significantly affected(P<0.05).There were no significant effects on meat quality(P>0.05).There were no significant effects on serum uric acid,total cholesterol and triglyceride contents in hens and serum uric acid,blood glucose and total cholesterol contents in cocks(P<0.05).The serum total protein,albumin and glucose contents of hens were significantly affected(P<0.01).The contents of total protein,albumin and triglyceride in serum of cocks were significantly affected(P<0.05).(2)Dietary energy level had extremely significant effects on average daily feed intake and serum uric acid content of hotan Black chickens aged 14 to 17 weeks(P<0.01),and had significant effects on serum total protein content of hens and serum total protein and blood glucose content of cocks(P<0.05).The interaction of dietary energy and protein had significant effects on serum glucose content of hens(P<0.01),and serum uric acid and triglyceride contents of cocks(P<0.05).Dietary protein level had a significant effect on serum glucose content of cocks(P<0.01).Dietary energy and protein levels had extremely significant(P<0.01)or significant(P<0.05)effects on feed to gain and slaughter rate among all treatment groups.The serum uric acid content of hens,serum total protein,blood glucose and uric acid content of cocks were significantly affected(P<0.01)or(P<0.05).It had a significant effect on average daily feed intake(P<0.01).Serum glucose content of hen and serum triglyceride content of rooster had significant effects(P<0.01).It had significant effects on daily gain,half-evisceration rate,total protein and albumin contents in serum of hens(P<0.05).Serum total cholesterol and triglyceride of hens and serum total cholesterol of roosters had no significant effects among all treatment groups(P>0.05).There were no significant differences in meat quality indexes.Considering the above indices,it is recommended that Hotan black chickens aged from 8to 13 weeks should be fed diets with 11.51 MJ/kg and 16.50% ME and CP levels.From 14 to 17 weeks of age,diets with ME and CP levels of 12.34 MJ/kg and 16% were selected.