Effects of Dietary Metabolizable Energy and Crude Protein Levels on Performance,Egg Quality and Reproductive Performance of Dawu Jinfeng Laying Breeders Hens during Late Laying Period
This study was conducted to investigate the effects of dietary metabolizable energy(ME)and crude protein(CP)levels on the performance,egg quality and reproductive performance of Dawu Jinfeng breeder hens during late laying period,in order to determine appropriate levels of ME and CP in the diet and provide scientific basis for the formulation of feeding standards for Dawu Jinfeng breeder hens.A total of 648 Dawu Jinfeng breeder hens at the age of 51 weeks with similar body weight and laying rate were randomly divided in-to 9 groups,each of which included 6 replicates of 12 hens.A 3 × 3 factorial design with three levels of ME(10.60,11.10 and 11.60 MJ/kg)and three levels of CP(14.50％,15.50％ and 16.50％)was used in this experiment to prepare 9 experimental diets.The pre-trial period was 7 d,and the trial period was 84 d.The re-sults showed as follows:1)dietary ME level had significant effects on the average daily feed intake(ADFI)and laying rate of breeder hens during late laying period(P＜0.05).The and ADFI and laying rate increased with dietary ME level decreasing(P＜0.05),which in the high ME group was significantly lower than that in the medium and low ME groups(P＜0.05).Dietary CP level significantly affected the laying rate and feed/egg ratio of breeder hens(P＜0.05),as the dietary CP level decreasing,the laying rate of breeder hens decreased,and the feed/egg ratio increased.There was a significant interaction between dietary ME and CP levels on lay-ing rate of breeding hens(P＜0.05).2)There was no significant effect of dietary ME level on egg quality of breeder hens(P＞0.05).The Haugh unit was significantly affected by dietary CP level(P＜0.05).Haugh unit decreased with the dietary CP level decreasing,and it in the low protein group was significantly lower than that in the medium and high protein groups(P＜0.05).3)Dietary CP level significantly affected the hatchability of fertile eggs,and it in the low protein group was significantly higher than that in the high protein group(P＜0.05).4)Dietary ME level significantly affected the contents of estradiol(E2)and progesterone(P4)in ser-um of breeder hens(P＜0.05),as the dietary ME level decreasing,the serum E2 and P4 contents were de-creased.Dietary CP level significantly affected the contents of follicle stimulating hormone(FSH),E2,P4 and gonadotropin releasing hormone(GnRH)in serum of breeder hens(P＜0.05),and the serum FSH,E2,P4 and GnRH contents were decreased with the dietary CP level decreasing.Based on the comprehensive perform-ance and reproductive performance indicators,it is recommended that the levels of ME and CP in the diet for Dawu Jinfeng breeder hens during late laying production are 11.13 MJ/kg and 15.50％,respectively.[Chinese Journal of Animal Nutrition,2023,35(12):7724-7734]
Dawu Jinfeng breeder henslate laying periodmetabolizable energycrude protein
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