A Study Of Metabolizable Energy Requirement Of Laying Hens At The Stage Of Egg-laying Peak

A single factor completely randomized experiment was conducted to determine howNick Laying Hens would respond to an increase or decrease in dietary energy. Two hundredand twenty Nick Laying hens were randomly divided into5treatments with4replicates of11hens per treatment. The experiment lasted for26weeks from25to51weeks old. The energyof these diets were assessed using laying hens and the5treatments were fed the diets withdifferent levels of diets energy,10.07,10.63,10.91,11.41and11.78MJ of ME/kg, respectively.The protein content and other nutrient content were balanced according to NY/T33-2004. Theresults are summarized as follows:(1) As dietary energy increased from10.07to11.78MJ of ME/kg, egg production in-creased at first and then dropped. The highest egg production was observed at the treatment ofME11.41MJ/kg, however, significant difference was not observed in different treatments.EM was not effected by dietary energy level. Egg weight and body weight gain tended to beincreased by increasing the energy levels in diets, but significant difference was not observed.Dietary energy had a significant effect on feed intake (P＜0.01). With the increase of dietaryenergy levels, feed intake and the rate of feed to egg was linearly decreased.(2) With the increase of energy levels in diets, MEI tended to be increased, however,significant difference was not observed in different treatments. Increasing the ME levels sig-nificantly increased the amount of ME that were used to produce1g of eggs(P＜0.05). Addi-tionaly, The high level of dietary energy significantly decreased the intake of CP and the re-quirement of CP to produce1g of eggs. Dietary energy had a significantly positive effect onMCP (P＜0.01).With the increase of ME, AMCP was significantly increased. The result in-dicated that high level of ME could improve the efficiency of CP.(3) Among egg quality parameters in this experiment, only yolk color, yolk weight andthe percent of yolk were effected (P<0.05) by different levels of energy in diets. Haugh unittended to be decreased by increasing the energy levels in diets, but there was no significantdifference (P=0.713).In summary，dietary energy had no significant effect on the main parameters of perfor- mance and egg quality, however, improve the ME levels from10.07MJ/kg to11.78MJ/kg, cansignificantly improve the efficiency of crude protein.