The Study On Breed Characters And Utilization Of Recessive White Chickens

This paper focused on the French Recessive White chickens introduced bynational "948" program, they were fed according to the traditional rearing conditions,and then the egg productivity and meat productivity were measured. The eggproductivity included the measurement of egg productivity and the heritability of theparameters of egg productivity. For the meat productivity, the chickens were fed withthe same ration before 6 weeks and were fed with 6 kinds of rations composed of 2levels of energy(11.79MJ/kg, 12.96MJ/kg) and 3 levels of protein(15.1%, 18.0%,21.0%) during 7 to 12 weeks. The body weight, body size, slaughter traits, musclequality and nutrient composition were measured. Then we started the successiveselection and cross utilization based on this. The results were following:1. Phenotype distribution of egg productivity performance and mianly egg productivitytraitsFor the stocks: the egg-laying rate was 5.57% and the average egg weight was 43gat the age of 24 weeks. The egg production was 174.5, and the average egg weight was61.5g at the age of 63 weeks. The feed consumption was 47.5kg during 0 to 63 weeks.The percent of the hens which had nesting habit was about 17.7%, and the averageperiod of nesting was about 1.7 weeks. The model of egg weight was:W_(t)=65.562-25.231×exp(-0.143×t)(R²=0.997).The curve of egg production rate was:Y_(t)=90.736×exp(-0.013×t)/[1+exp(-0.825)×(t-3.415)] (R²=0.984).For the individuals: the average age of starting to lay eggs was 189.7 days, theaverage weight of the first egg was 50.5g and the average body weight of laying the firstegg was 2.2kg. The production of eggs was 91.2 at the age of 44 weeks. The bodyweight of 24 weeks, age of laying the first egg, weight of the first egg and eggproduction of 44 weeks indicated positive kurtosis, but the body weight of laying thefirst egg indicated negative kurtosis. The age of laying the first egg indicated positiveslope, and the egg production of 44 weeks indicated negative slope.2. The meat productivity and effect of levels of energy, protein on the meatproductivity after 6-week-oldSexes had significant or very significant effects on the body weight, body slopelength and breast width after 2 weeks; on the fossil bone length, shank length and shankcircumference after 8 weeks; on the head width, head circumference, meat production,meat production rate except for thigh weight rate, by-production, by-production rate except for wing weight rate, muscle shear force and water losing rate. The cocks hadhigher levels than hens among all the traits above except for breast muscle rate,abdominal fat rate, abdominal fat weight, liver weight rate, stomach weight rate andwater losing rate. The two levels of energy in the rations only had significant or verysignificant effects on the body weight, slaughter weight, semi-eviscerated rate,eviscerated rate, abdominal fat weight, abdominal fat rate, stomach weight, stomachweight rate at the age of 12 weeks. High levels of protein could remarkably increasedthe body weight after 8 weeks and eviscerated rate, eviscerated weight, breast muscleweight and breast muscle rate of 12 weeks, but more than the level of 18.0% had nosignificant effects. Low levels of protein could remarkably increased abdominal fatweight, abdominal fat rate, liver weight and liver weight rate; it also could increasedmuscle shear force and decreased water losing rate.3. Heritability of the traitsThe heritability of the traits of the body weight of 8 weeks and 24 weeks, age oflaying the first egg, body weight of laying the first egg, weight of the first egg and eggproduction of 44 weeks were 0.42, 0.38, 0.15, 0.39, 0.42 and 0.08. The heritability ofthe weights of 1 to 6 weeks were 0.43～0.57, and that were 0.33～0.58 for the weights of7 to 12 weeks. The heritability of mature body weight, body weight of the birth,parameters of growth rate, weeks of rapid growth and weight during rapid growthperiod were 0.22, 0.39, 0.15, 0.33 and 0.14. The heritability of body parameters weremiddle, and that of the meat production and by-production rate were higher than middlewhich were 0.36～0.43 and 0.25～0.77. The heritability of meat rate and by-productionhad significant difference, that were 0.36～0.43 and 0.16～0.59. The heritability of pH,meat color, shear force and water losing rate were0.14, 0.29, 0.64 and 0.41. Theheritability of crude ash, P, Ca, crude protein, water contents and fat contents of musclewere 0.15, 0.53, 0.48, 0.28, 0.49 and 0.57.4. Pure selection and breedingThe average age of starting to lay the first egg advanced 5 days, the egg productionof 40 weeks increased by 8 and that of the 66 weeks increased by 6 and the uniformlevel and the productivity were also promoted after 6 generations' selection.5. The cross utilizationCombining ability and pure selection were performed on the base of the RecessiveWhite chickens, and formed the new breed-Weiyang partridge chickens. The crossmodel was:Gushi^♂×(Chongren partridge^♂×Recessive white chickens_♀)_♀. The breedwas approved by Jiangsu Domestic Animal Breeds Examined Committee in 2004.Thecriterias "Weiyang partridge chichens" and "the industrial procedures of Weiyangpartridge" were approved by Jiangsu Quality Supervisal Bureau.