Effect of Methionine Source and Dietary Crude Protein Level on Growth Performance, Carcass Traits and Nutrient Retention in Chinese Color-feathered Chicks

A total of 1,200 LinNan Chinese color-feathered chicks were used to study the effects of methionine source [DL-2-hydroxy-4-methylthio-butanoic acid (HMTBa) or DL-methionine (DLM)] and dietary crude protein (CP) level on growth performance, carcass traits, and whole-body nitrogen and fat retention. The trial was designed as a 2x2 factorial arrangement, including two CP levels (adequate and low) and two methionine sources (HMTBa and DL-methionine). Diets were formulated for three phases, starter (0-21 d), grower (21-42 d), and finisher (42-63 d). Chicks fed HMTBa had higher daily gain and improved feed efficiency than DLM during the grower phase (p 0.05). Chicks fed low-CP diets grew slower, used feed less efficiently during the grower, finisher phase and overall. On d 42, regardless of dietary CP levels, birds fed HMTBa had higher carcass weights, breast and thigh weights than DLM-fed birds (p