Study On The Protein Requirement Of Lueyang Black-bone Hens During The Laying Period

As a kind of fine local breed, Lueyang black-bone hen (LBH) was an importantcomponent in biological genetic resources in our country, native to Lueyang County ShaanxiProvence. It had the value of meat, egg and ornamental, and had been well known for its famousmedicinal value. Currently, available studies focused on its growing requirements, less uponlaying requirements. So far, there was not standards of LBH.This study was conducted to investigate the effects of dietary crude protein (CP) levels onproductive performance, egg quality and the nutrient metabolism of LBH during the layingperiod, and to gain the protein requirement of LBH. A total of192LBH aged34weeks with nosignificant difference of body weight and egg production were randomly allocated to4groupswith4replicates per group and12chickens per replicate, a single factorial arrangement wasused. Chickens were fed with4diets containing the same metabolizable energy(ME,10.88MJ/kg) level and different crude protein(CP) levels. The pre-trial period was one week and thetrial period was sixteen weeks. The results showed as follows:(1) The dietary CP levels had no significant effects on egg production with a certainrange(14.40%-16.21%)，a s the dietary CP level increased， the egg production of16.83%group decreased significantly(P<0.05).The dietary CP levels had no significant effects onaverage egg weight, average egg mass, average feed intake and feed/egg (P>0.05).(2) The dietary CP levels had no significant effects on egg shape index(ESI), shellthickness(ST), shell breaking strength (SBS), albumen height (AH) and Haugh units(HU)(P>0.05). The dietary CP levels had significant effects on the CP content of yoke(P<0.05).(3) The dietary CP levels had no significant effects on the nutrient metabolism (P>0.05).(4) According to the results of productive performance, egg quality and the nutrientmetabolism, it was recommend that the protein requirement of LBH aged35to50wk was14.40%during the laying period.