Study On Protein Requirement Of Laying Luxi Game Chickens

A series of experiments were conducted to study the effects of dietary crude protein levelon production performance, egg quality, serum biochemical parameters, egg composition,body composition, nutrients utilization and nitrogen retention of laying Luxi game chickensaged26to41weeks. Factorial models had been established by means of rearing, metabolismand comparative slaughter experiments, and concluded protein requirement of laying Luxigame chickens.A single factor design was used to a16week experiment to study the effects of dietarycrude protein level on production performance, egg quality and serum biochemical parametersof Luxi game chickens aged26to41weeks. Two hundred26-week-old hens with the averagebody weight of （1.952±0.288） kg were randomly distributed into four groups with fivereplicates per group and ten hens per replicate. Four dietary crude protein levels were14.00%,15.50%,17.00%and18.50%. All birds were restrictively fed the same amount of diets.Result showed that from26to29weeks of age, dietary crude protein level did not affectlaying rate, the ratio of feed to egg and average weekly egg mass of Luxi game chickens（P>0.05）. From30to37weeks of age, laying rate and egg mass of the17.00%group washigher than other groups （P <0.05）, but the feed conversion rate was not significantly affectedby dietary crude protein levels （P>0.05）. From38to41weeks of age, laying rate and feedefficiency of the highest crude protein level （18.50%） was higher than other groups （P <0.05）.Average egg size of Luxi game chickens aged26to41weeks was not significantly affectedby dietary crude protein level （P>0.05）. Meanwhile, egg quality was significantly affected bydietary crude protein levels. With the increase of dietary crude protein level, there was adownward trend in yolk color（P=0.09）, albumen high and Haugh unit of17.00%and18.50%groups were significantly higher than those of14.00%and15.50%groups （P <0.05）. BUN ofthe14.00%group was significantly lower than the17.00%and18.50%group （P <0.05）. TP, GLOB and A/G was not significantly affected by dietary crude protein levels（P>0.05）.A single factor design was used to study the effects of dietary crude protein level onnutrients utilization and nitrogen retention of laying Luxi game chickens. Sixty35-week-oldhens with the average body weight of （2.046±0.101kg） were randomly distributed into fivegroups with six replicates per group and two hens per replicate. Four dietary crude proteinlevels were14.00%,15.50%,17.00%and18.50%, and endogenous losses were obtained fromanother group.Results showed that all hens had similar apparent and true metabolic rate of DM, OM,Ash and GE （P>0.05）. In addition to the18.50%group, the apparent metabolic rate of CP ofthe17.00%group was significantly higher than the other groups （P <0.05）. However, the truemetabolic rate of CP was not significantly affected by dietary crude protein levels （P>0.05）;the nitrogen excretion linearly （P <0.01） increased as dietary crude protein level increasedfrom14.00%to18.50%. The retention rate of nitrogen of the17.00%group was significantlyhigher than the14.00%group （P <0.05）. The regression equation of daily nitrogen retention（Nr） and daily nitrogen intake （Ni） for Luxi game chickens was Nr=0.649Ni-0.258（R2=0.923）. Nitrogen maintenance requirement for laying Luxi game chickens at35-week-old was0.2164g/kgBW^0.75.Research on nutrients retention of laying Luxi game chickens in different dietary crudeprotein levels was conducted as follows. At the beginning of the rearing test（26week）,3hens were slaughtered as contrast, and extracted twenty eggs determine chemical composition.At the end of the rearing tes（t41week）, twelve hens were also slaughtered. Meanwhile, fortyeggs were extracted to determine chemical composition with ten eggs per group.Results showed that all hens and eggs had similar composition of CP, EE, OM, Ash, DMand GE （P>0.05）. The body and egg chemical composition of Laying Luxi game chickensremain stability.Crude protein intake（CPI）, average daily gain（ADG） and average daily egg mass（EM）were regarded as dependent variable（Y）, independent variable （X1） and independentvariable （X2） respectively, then multiple linear regression were made, the result as follows:from26to29weeks: CPI=3.52ADG+0.35EM+2.18BW^0.75; from30to37weeks: CPI=4.02ADG+0.35EM+2.42BW^0.75; from38to41weeks: CPI=3.09ADG+0.53EM+ 2.10BW^0.75.Through integrated account of average daily gain, average daily egg mass andmetabolic body weight of the best production performance group, the dietary appropriatecrude protein level for laying Luxi game chickens during the early period （26to29weeks）,middle period（30to37weeks）, and late period（38to41weeks）are14.19%,16.92%and18.28%, respectively.