Methionine Requirements For Lueyang Black-boned Chicken During The Growth Period

In order to investigate the methionine requirements of Lueyang black-bonedchicken during the growth period, three experiments were carried out. In experiment1,sixteen adult Lueyang black-boned male chickens with similar body weight wereallocated into2groups, one group was the endogenous alignment group [body weight,（2.14±0.12）kg], and the other group was the experimental group [body weight,（2.09±0.14）kg]. Lueyang black-boned chickens were used to measure the apparentdigestible of methionine and the true digestible of methionine. eight chickens weretube-fed with free-protein diets and the other eight individuals were tube-fed with lowmethionine diet. In experiment2, six hundred6week-old Lueyang Black-bonedchickens were randomly allocated into5groups with6replicates per group and20birds per replicate. A single factorial experiment containing5methionine levels(0.22%,0.32%,0.42%,0.52%and0.62%) was undergone. This experiment wasconducted to evaluate the effects of dietary methionine level on growth performance,serum biochemical parameters and the development of tissues and organs. Inexperiment3, six hundred12week-old Lueyang Black-boned were selected, male andfemale each300randomly divided into five groups, each six replicates of10chickens,feeding separate male and female. A single factorial experiment containing5methionine levels (0.22%,0.32%,0.42%,0.52%and0.62%) was undergone. Thisexperiment was conducted to evaluate effects of dietary methionine levels on growthperformance, serum biochemical parameters, carcass performance and thedevelopment of some organs, to determine the methionine requirement of LueyangBlack-boned chickens aged from13to18weeks. The results of three experimentswere as follow:1The methionine digestibility of the low methionine diet for Lueyangblack-boned chicken Used the gavage-total feces collection method, and corrected the endogenouslosses of amino acids by the N-free diet, the apparent digestibility of methionine wasmeasured as92.05%, true digestibility was measured as94.97%.2The effects of dietary methionine levels on the growth performance, serumbiochemical parameters and the development of tissues and organs during7to12weeks1) The average daily feed intake (ADFI) was significantly decreased by themethionine level (P<0.01). The average daily gain (ADG) was increased first and thendecreased quadratically (P<0.01， R2=0.691). Different methionine levels had nosignificant effect on feed/gain (F/G)(P>0.05). However, with the methionine levelincreasing, F/G was decreased first and then increased in a quadratic trend （P>0.05，R2=0.204）. Different methionine levels significantly affected the relative growth rate[RGR(%)=100×body weight/initial body weight](P<0.05).2) Different levels of methionine have no significant effect on serum biochemicalparameters (P>0.05).3) Different levels of methionine did not have significant impacts on breastmuscle rate, leg muscle rate, abdominal fat percentage as well as some organsdevelopment (P>0.05).3The effects of dietary methionine levels on growth performance, serumbiochemical parameters, carcass performance and the development of some organsduring13to18weeks1) Different methionine levels had significant effect on the average dailyintake(ADFI) of13to15week-old female chickens(P<0.05),the feed/gain (F/G) of13to15week-old male chickens was significantly affected by the methioninelevels(P<0.05).When methionine levels was0.32%~0.42%the F/G of male andfemale chickens were lower then other groups; Different methionine levels had nosignificant effect on the F/G of16to18week-old male and female chickens(P>0.05);Different levels of methionine effect the F/G of13to18week-old malechickens(P<0.05);No significant effect was observed on the growth performance of13to18week-old female chickens(P>0.05).Compared with other treatment groups,the minimum F/G of13to18week-old male and female chickens was in thetreatment group2(0.32%).2) There were no significant effects on the serum biochemical parameters of13to18week-old male and female chickens (P>0.05). 3) Methionine levels had significantly effect on the eviscerated rate and breastmuscle percentage of13to18week-old male chickens(P<0.05). Compared with othergroups, the eviscerated rate of treatment group2(0.32%) was highest; The carcassperformance of female chickens was not effected significantly by the methioninelevels (P>0.05).4) Different levels of methionine had no significantly effects on the developmentof internal organs, immune organs as well as some digestive organs (P>0.05).Conclusion: According to the growth performance, the development of tissuesand organs and the serum urea acid and urea nitrogen contents,1) the methioninerequirement of Lueyang black-boned chickens from7to12weeks is0.354%, theapparent digestible methionine requirement is0.326%, and the true digestiblemethionine requirement is0.336%.2) the methionine requirement of male and femaleLueyang black~boned chickens from13to18weeks is0.32%~0.42%, the apparentdigestible methionine requirement is0.295%~0.387%, and the true digestiblemethionine requirement is0.304%~0.399%.