| In this paper,two experiments were conducted to investigate the effects of different levels of corn DDGS and corn germ meal on growth performance,carcass traits,meat quality,serum biochemical indices,nutrient utilization,and standard ileal amino acid digestibility(SIDAA)of meat ducks,and to determine the dietary optimal dosage of corn DDGS and corn germ meal via the liner and quadratic regression analisis.The study will provide theoretical basis and data support for the scientific and rational use and the substitution of corn and soybean of corn DDGS and corn germ meal in meat duck industry.Experiment 1: Effects of DDGS levels on growth performance,serum biochemical index,meat quality and dietary nutrients digestibility and utilization in meat ducks.A total of 672 Cherry Valley drake ducks were randomly divided into 6 groups with 7replicates(16 ducks per page)in one-factor completely randomized design.The experimental diet was corn miscellaneous meal type.Six isonitrogenous and isocaloric experimental diets were formulated on a digestible amino acid basis to produce diets in which containing 0%,5%,10%,15%,20%,and 25% DDGS,respectively.The experiment lasted for 32 days,starting at 11 days of age and ending at 42 days of age.Results showed as follows:1)With the increase of dietary DDGS levels,42 d body weight(BW),average daily gain(ADG),average daily feed intake(ADFI),feed to gain ratio(F: G)and mortality rate showed a linear or quadratic change(P<0.05).Compared with 0%,5%,and 10% groups,ducks fed 20% and25% groups significantly decreased BW(42d)(P<0.05),and the ADG of 25% group was significantly decreased(P<0.05).The mortality of 25% group was significantly higher than other groups(P<0.05).2)The weight of carcass,eviscerated with giblet,eviscerated and breast muscle presented a liner and quadratic decrease(P < 0.05)with the increase of dietary DDGS levels.Compared with0%,5%,and 10% groups,ducks fed 20% and 25% groups significantly decreased the weight of carcass eviscerated with giblet,eviscerated and breast muscle(P < 0.05),the percentage of breast muscle was significantly decreased(P < 0.05).3)With the dietary DDGS level increasing,the p H,muscle fiber density,moister and fat content of breast muscle in meat duck presented a linear and quadratic increase(P < 0.05).And the b* of 45 min and 24 h presented a liner increase(P < 0.05).Compared with 5%,10% and 20%groups,the 45 min L* of 25% group significantly decreased(P < 0.05),the content of moister in breast meat was higher than other groups(P < 0.05).4)The liver index of 25% group was significantly higher than that of 0%,5%,10% and 20%groups(P<0.05).Compared with other groups,The ileum crypt depth in 20% group was significantly higher(P<0.05).5)With the increase of DDGS levels,the contents of total cholesterol(TC)and triglyceride(TG)in serum showed linear and quadratic changes(P<0.05).Compared with 0% group,serum total cholesterol content in 20% group was significantly increased(P<0.05).Serum triglyceride content in 15% and 20% groups was significantly higher than that in 0% and 5% groups(P<0.05).6)With the dietary DDGS levels increasing,the utilization of energy,crude protein(CP),ether extract(EE)and dry matter(DM)showed a linear and quadratic change(P<0.05).The utilization of energy,crude protein and dry matter in 15% and 25% groups were significantly lower than those in 0%,5%,10% and 20% groups(P<0.05).Ducks fed 10% DDGS significantly decrease the ether extract utilization(P<0.05).DDGS levels had no significant effect on the standard ileal digestibility of essential and non-essential amino acids(P>0.05).These results suggested that the optimal DDGS dosage for meat ducks is 5-10%,considering growth performance,carcass traits,meat quality,serum lipid metabolism and nutrient utilization.Experiment 2: Effects of corn germ meal(CGM)levels on growth performance,serum biochemical index,meat quality and dietary nutrients digestibility and utilization in meat ducks.A total of 504 Cherry Valley drake ducks were randomly divided into 6 groups with 6replicates(14 ducks per page)in one-factor completely randomized design.The experimental diet was corn miscellaneous meal type.Six isonitrogenous and isocaloric experimental diets were formulated on a digestible amino acid basis to produce diets in which containing 0%,3%,6%,9%,12%,and 15% CGM,respectively.The experiment lasted for 32 days,starting at 11 days of age and ending at 42 days of age.Results showed as follows:1)Dietary CGM levels had no effect on the growth performance and mortality(P > 0.05).2)The weight and percentage of breast meat presented a quadratic decrease with increasing of dietary CGM levels(P < 0.05).There were no significant effect on slaughter performance of meat duck(P>0.05).3)The content of crude protein in breast meat presented a linear decrease with increasing dietary CGM levels(P < 0.05).Compared with 0%,3% groups,the content of breast muscle protein in 9%,12% groups was significantly decreased(P < 0.05).There was no significant difference on drip loss,p H,color,and the content of moisture and fat in breast meat among all treatments(P >0.05).4)With the dietary CGM levels increasing,the crypt depth and villus height to crypt depth ratio(V/C)of jejunum showed a liner and quadratic increase(P < 0.05).The crypt depth and villus height to crypt depth ratio of ileum presented a liner increase with increasing dietary CGM levels(P < 0.05).The ileum crypt depth in 15% group was significantly higher than other groups(P<0.05).5)The content of glucose and high-density lipoprotein in serum showed a quadratic change with increasing dietary CGM levels(P < 0.05).Compared with 9% and 12% groups,the content of low-density lipoprotein cholesterol in serum of ducks in 15% group was insignificantly decreased(P < 0.05).6)Compared with 9% group,the utilization rates of energy in 0%、3% and 6% groups were significantly increased(P<0.05).The utilization of crude protein in 6%,9%,12%,and 15% groups were significantly lower than those in 0% and 3%(P<0.05).Compared with 0%,3%,9%,and 12%groups,the SID of Arg in 15% CGM groups was significantly decreased(P<0.05).The SID of His in 15% group was significantly decreased than those in 9% and 12% groups.Compared with other groups,the SID of Ile and Pro in 15% group was significantly decreased(P<0.05).The results indicated that the appropriate dosage of CGM for meat ducks should not exceed 9%,considering growth performance,carcass traits,meat quality,serum biochemical indices,nutrient utilization,and(SIDAA).In conclusion,based on the results of growth performance,carcass traits,meat quality,serum biochemical indices,nutrient utilization,and standard ileal amino acid digestibility(SIDAA),the optimal DDGS dosage of corn miscellaneous meal type diet is 5%-10%.The amount of corn germ meal in corn-miscellaneous meal type diet should not exceed 9%. |
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