Reevaluation of methionine requirement based on performance and immune responses in broiler breeder hens

Abstract

This experiment was conducted to study methionine requirements in broiler breeder hens aged from 26-35 weeks. The treatments were consisted of six levels of methionine (0.2, 0.25, 0.3, 0.35, 0.4 and 0.45%), with five replicates of eight birds (Seven hens and one rooster). The results showed that different levels of methionine had no significant (p>0.05) effects on egg weight, unsettable (double yolk, small size) and settable eggs. The methionine levels significantly (p<0.05) changed egg production percentage, egg mass (g/h/d), egg content (g) and feed conversion ratio. Different levels of methionine did not affect on cell-mediated responses, newcastle and bursa diseases titer, and IgM (p>0.05), but total titer against sheep red blood cell (SRBC) and IgG responses were influenced (p< 0.05). Using of two-slope quadratic broken-line analysis indicated that methionine requirements for egg mass (g/h/d), feed conversion ratio, settable eggs, SRBC and IgG were 446, 450, 494, 580 and 492 (mg/d), respectively. In conclusion, methionine requirement for settable eggs was similar to those needed for the optimum immune responses. Since, settable eggs are an important factor in broiler breeder industries, so the authors recommend 494 mg/d methionine for broiler breeder hens. This amount is higher than those needed for egg mass and feed conversion ratio. Copyright © 2012, Japan Poultry Science Association.