Study On Protein Requrierment And Metabolism Regularity In The Laying Period Of Wenshang Luhua Chicken

The purpose of this study was to research the laying period of Wenshang Luhua chicken,and to investigate the effects of dietary protein levels on the production performance,protein deposition,and protein metabolism of Wenshang Luhua chicken.The protein requirement models of Wenshang luhua chicken were constructed by feeding,metabolic and slaughtering experiments,combining with the production status.A total of 1,250 20-week-old Wenshang Luhua chickens were selected and randomly divided into 5 treatments.Each treatment consisted of 5 replicates and each replicate consisted of 50 chickens.The feeding experiment was divided into two stages.The five isoenergetic gradient protein diet groups CP1,CP2,CP3,CP4,and CP5.The protein levels at the 20 to 35-week-old diet were 15.0%,15.5%,16.0%,16.5%and 17.0%respectively;the 36to 56-week-old dietary protein levels were 15.5%,16.0%,16.5%,17.0%and 17.5%respectively.Metabolic rate of nitrogen was determined by two metabolic tests at 26 and 40weeks of age.Body composition was determined by two slaughter tests at 24 and 46 weeks of age.Eggs were taken at 40 weeks of age to determine the egg composition.Blood was collected at 40 weeks of age to determine serum biochemical indicators.Production performance study:The results of feeding experiments with isoenergetic gradient protein levels showed that dietary protein levels only significantly affected feed intake at 29 to 42 weeks of age?P<0.05?,average egg weight at 29 to 35 weeks of age?P<0.05?,and feed to egg ratio at 50 to 56 weeks of age?P<0.05?,which did not affect feed intake,average egg weight,and feed to egg ratio at other layig stages?P>0.05?.There were no significant differences in egg production rate and egg mass among the levels of dietary protein in this test.Research on protein deposition:According to the slaughter test at 24 and 46 weeks of age and the determination of body composition,the dietary protein level had no significant effect on body composition at 24 and 46 weeks of age?P>0.05?.The measured mean body nitrogen content were 0.0367g/g and 0.0325g/g,respectively.The results showed that the content of body protein decreased with the increase of week age.The egg composition was determined by taking eggs at 40 weeks of age,and the results showed that dietary protein levels had no significant effect on egg composition?P>0.05?,and the average nitrogen content of fresh eggs was 0.0201 g/g.Actual production data analysis:Through the investigation of feed intake,laying rate and egg mass of about 80,000 Luhua chickens in 7 laying periods from 2015 to 2019,the production performance variation rule of Luhua chickens in egg production stage was explored.The results show that the change of performance of this experiment was consistent with the actual production law.Egg production rate was defined as above 65%to enter the peak egg production period.The egg production period of the Wenshang Luhua chicken was divided into the early stage of egg production at 21²3 weeks,the peak stage of egg production at 24⁴5 weeks and the later stage of egg production at 46⁵6 weeks to study the protein requirement of laying Wenshang Luhua chicken.Metabolic tests and nitrogen balance studies:The results of metabolic tests at 26 and40 weeks showed that there was no significant difference in nitrogen metabolic rate between two stages?P>0.05?,indicating that there was no significant change in nitrogen metabolic rate with the growth of weekly age in the laying period of the Wenshang Luhua chicken.The results of nitrogen balance showed that protein intake,nitrogen intake,nitrogen excretion and nitrogen retention increased significantly with the increase of dietary protein level?P<0.05?in the early egg production?21²3wk?.Dietary protein levels significantly affected protein intake,nitrogen intake,and nitrogen retention during the peak egg production?24⁴5wk??P<0.05?,but did not affect nitrogen excretion?P>0.05?.Dietary protein levels had no significant effect on nitrogen balance in the late laying period?46⁵6wk??P>0.05?.Study on the protein metabolism and requirements:Based on the results of the breeding test,metabolic test,slaughter test,egg composition analysis,and research on the current situation of the production of Wenshang Luhua chicken,this experiment had established the protein requirement coefficient and transformation efficiency of each stage of laying period through factorial analysis.In the early stage of egg production?21²3wk?:The coefficients of crude protein requirements for maintenance,weight gain and egg production were 2.46 g/BW^0.75kg,0.46 g/g?DG?and 0.69 g/g?EM?,respectively;the coefficients of net protein requirements for maintenance,weight gain and egg production were 1.57g/bw^0.75kg,0.23g/g?DG?and 0.13g/g?EM?;the conversion efficiencies of net protein for maintenance,weight gain and egg production were 0.64,0.50 and 0.18,respectively.In the peak egg production period?24⁴5wk?:the crude protein requirement coefficients for maintenance,weight gain and egg production were 2.40 g/BW^0.75 kg,0.54 g/g?DG?and 0.32 g/g?EM?;the net protein requirement coefficients for weight gain and egg production were 1.53 g/BW^0.75kg,0.22 g/g?DG?,and 0.13 g/g?EM?;the conversion efficiencies of net protein for maintenance,weight gain,and egg production were 0.64,0.40,and 0.39.In the later egg production period?46⁵6wk?,the coefficients of crude protein requirements for maintenance,weight gain and egg production were 1.97 g/BW^0.75kg,0.51 g/g?DG?and 0.36 g/g?EM?,respectively;the net protein requirement coefficients for maintenance,weight gain and egg production were 1.26g/BW^0.75kg,0.20 g/g?DG?and 0.13 g/g?EM?,respectively;the conversion efficiencies of net protein for maintenance,weight gain and egg production were 0.64,0.40 and 0.35,respectively.Based on the above studies,the protein nutrient requirement factorial models for egg production of Wenshang Luhua chicken were developed as follows:Early egg production?21²3wk?CPR=2.46BW^0.75+0.69EM+0.46DG;NCPR=1.57BW^0.75+0.13EM+0.23DG;Peak egg production?24⁴5wk?CPR=2.40BW^0.75+0.32EM+0.54DG;NCPR=1.53BW^0.75+0.13 EM+0.22DG;Late Laying Period?46⁵6wk?CPR=1.97BW^0.75+0.36EM+0.51DG;NCPR=1.26BW^0.75+0.13 EM+0.20DG.In the formula:BW^0.75:Indicates the metabolic weight,the unit is kg;EM:Indicates the daily egg mass,the unit is g;DG:Indicates the daily weight gain,the unit is g;CPR:Represents the daily crude protein requirement of each chicken,the unit is g/d/bird;NCPR:Represents the daily net protein requirement of each chicken,the unit is g/d/bird.