Optimal Dietary Metabolizable Energy and Crude Protein Levels for Dawufen No.1 Commercial Layer Chicks from 0 to 4 Weeks of Age

ZHANG Meng;LI Qiang;LIU Ping;XU Lijun;SU Kun;WANG Dehe;ZHOU Rongyan;CHEN Hui;College of Animal Science and Technology,Hebei Agricultural University;College of Veterinary Medicine,Hebei Agricultural University;Hebei Dawu Farming and Animal Husbandry Group;Baoding Livestock Husbandry Workstation;

ZHANG Meng%LI Qiang%LIU Ping%XU Lijun%SU Kun%WANG Dehe%ZHOU Rongyan%CHEN Hui%College of Animal Science and Technology,Hebei Agricultural University%College of Veterinary Medicine,Hebei Agricultural University%Hebei Dawu Farming and Animal Husbandry Group%Baoding Livestock Husbandry Workstation

Dawufen No.1 commercial layer chicks;;metabolizable energy level;;crude protein level;;requirement

To determine the optimal dietary metabolizable energy(ME) and crude protein(CP) levels of hatch to 4-week-age Dawufen No.1 commercial layer chicks,the effects of dietary ME and CP levels on the growth performance,body size traits,organ indexes and serum biochemical indexes of 0 to 4-week-age Dawufen No.1 commercial layer chicks were evaluated,and the regression models between the dietary ME or CP levels and testing indexes were built.A 3×3 two-factor experiment design was adopted in this experiment.Nine experimental diets were prepared,the ME levels in diets were 12.01,12.51 and 13.01 MJ/kg,respectively,and the CP levels in diets were 19.81%,20.81% and 21.81%,respectively.Eight hundred and ten 1-day-old Dawufen No.1 commercial layer chicks with the same genetic background,similar body weight and good health were randomly divided into 9 groups with 6 replicates per group and 15 chicks per replicate.The experiment lasted for 28 days.The results showed as follows:1) dietary ME level had significant effects on the average daily gain(ADG),average day feed intake(ADFI),feed/gain(F/G),keel length,body weight,duodenum relative length and ileum relative length of layer chicks(P<0.05),and there was a significant quadratic curve relationship between dietary ME level and ADFI,F/G,the contents of serum glucose(GLU),triglyceride(TG) or total cholesterol(TC)(P<0.05).2) Dietary CP level had significant effects on the chest width,liver index,duodenum relative length and ileum relative length(P<0.05),and there was a significant quadratic curve relationship between dietary CP level and chest breadth(P<0.05).3) The interaction of dietary ME and CP levels had significant effects on ADG,F/G,duodenum relative length,ileum relative length and serum TG content(P<0.05).4) According to fit quadratic curve,the best levels of ADFI,F/G,serum GLU,TG and TC contents were obtained when dietary ME levels were 6.991,12.979,10.524,11.968 and11.775 MJ/kg,respectively,and the best levels of liver index and chest breadth were obtained when dietary CP levels were 20.402% and 20.730%,respectively.Overall,when growth performance,body size traits,organ indexes and serum biochemical indexes are considered together,the optimal dietary ME and CP levels for 0 to 4-week-age Dawufen No.1 commercial layer chicks are 11.812 MJ/kg and 20.566%,respectively.