Studies On Energy And Protein Requirements Of Wenshui Green-shell Layers In Late Laying Period

In this study,Wenshui green-shell layers were selected as the research objects to investigate the effects of different dietary energy and protein levels on performance,egg quality and serum biochemical indices of Wenshui green-shell layers in late laying period,and to construct a prediction model of energy and protein requirements of Wenshui green-shell layers through feeding,metabolic and slaughter tests.To determine the optimal energy and protein requirements of Wenshui green-shell layers under actual production conditions,and to provide theoretical basis and practical support for raising standards of Wenshui green-shell layers.Experiment 1:Study on energy requirements of Wenshui green-shell layers.45-week-old Wenshui green-shell layers hens were randomly divided into 5 treatment groups with 5replicates in each treatment group and 40 chickens in each replicate.Five energy feed groups were set for ME1,ME2,ME3,ME4 and ME5,and the energy levels of the diet were10.46MJ/kg,10.84MJ/kg,11.27MJ/kg,11.68MJ/kg and 12.05MJ/kg,respectively,and other nutritional indicators were consistent.The pre-test period is 14 days and the test period is 42 days.During the test,feed intake and production performance were recorded,egg quality and serum biochemical indexes were measured.The results showed that the feed energy level had a significant effect on feed intake,metabolic energy intake,egg production rate,egg weight,egg production and feed egg ratio of Wenshui green-shell layers（P < 0.01）,and had no significant effects on daily weight gain,average body weight and metabolic weight（P > 0.05）,and the ME3 feed group had the best production performance of 11.27 MJ/kg.Feed energy levels had significant effects on triglycerides and glucose in serum（P < 0.05）,but did not have significant effects on serum biochemical indexes of high-density lipoprotein,low-density lipoprotein,serum urea nitrogen,total protein and cholesterol（P > 0.05）.The energy level of feed had a significant effect on the average egg weight and yolk weight in egg quality（P <0.05）.Experiment 2:Study on protein requirements of Wenshui green-shell layers.45-week-old Wenshui green-shell layers were randomly divided into 5 treatment groups with 5 replicates in each treatment group and 40 chickens in each replicate.Five protein feeding groups were set for CP1,CP2,CP3,CP4 and CP5,and the protein levels were 14%,15%,16%,17% and 18%,respectively,and other nutritional indicators were consistent.The pre-test period is 14 days,the test period is 42 days,and the statistics during the test are the same as above.The results showed that the protein level of feed had a significant effect on the feed intake,egg production rate,egg production,feed egg ratio and protein intake of Wenshui green-shell layers（P < 0.01）,and had no significant effects on daily weight gain,average body weight and metabolic body weight（P >0.05）,and the CP3 feed group,that is,the feed protein level of 16%,was the best in the treatment group.The protein level of feed had a significant effect on the serum content of urea nitrogen in the serum index of Wenshui green-shell layers（P < 0.01）,and did not have significant effects on the serum high-density lipoprotein,low-density lipoprotein,triglycerides,total cholesterol,albumin and glucose of Wenshui green-shell layers（P > 0.05）.The level of dietary protein has a significant impact on the average egg weight,Hastelloy units,and protein height in egg quality（P < 0.05）.In summary,The energy and protein levels in the diet had a significant effect on the production performance,egg quality and serum biochemical indexes of Wenshui green-shell layers in the later stage of egg laying（P < 0.05）.Combined with the above research data,a prediction model for metabolic energy and crude protein requirements in the late stage of egg production was constructed:MER = 452.77BW^0.75+11.56EM+21.27 DG CPR = 2.15BW^0.75+0.38EM+0.48DGAccording to the prediction model,combined with the production test,the suitable dietary metabolic energy level and crude protein level of Wenshui green-shell layers in the late stage of egg laying were determined to meet the requirements of 11.25 MJ/kg and 15.80%,respectively.