title: Protein and body weight accretion of chicks on diets with widely varying contents of soyabean meal supplemented or unsupplemented with its limiting amino acids.
abstract: 1. Two studies were conducted to evaluate the effects of relative deficiencies of methionine and threonine on the growth performance of 8- to 21-d-old chicks fed on isoenergetic diets containing a wide range of crude protein (CP) concentrations from dehulled soyabean meal (SBM). 2. Chicks fed on graded levels of SBM containing supplemental methionine and threonine (BAL) accreted whole-body protein more efficiently (P < 0.05) than those receiving graded levels of unsupplemented SBM (DEF), and superior (P < 0.05) growth performance was also obtained at lower CP levels when chicks were fed on the BAL diets. 3. Voluntary food intake increased between 30 and 220 g CP/kg in chicks fed on DEF diets, whereas food intake of chicks fed on BAL diets increased only between 30 and 100 g CP/kg, after which it decreased between 100 and 220 g CP/kg. 4. Protein efficiency ratio (g gain per g protein intake) decreased with each incremental increase in CP between 30 and 260 g CP/kg, regardless of whether diets were BAL or DEE 5. These data indicate that maintaining a balanced ratio of amino acids is a preferable approach when poultry producers are interested in employing low CP diets for economic, physiological or environmental reasons.
authors.affiliation: Department of Animal Sciences, University of Illinois, USA.
authors.forename: J L
authors.initials: JL
authors.lastname: Emmert
authors.forename: H M
authors.initials: HM
authors.lastname: Edwards
authors.forename: D H
authors.initials: DH
authors.lastname: Baker
mesh_terms: D000818:Animals; D001835:Body Weight; D002645:Chickens / Q000254:growth & development* / Q000378:metabolism; D004044:Dietary Proteins / Q000008:administration & dosage* / Q000378:metabolism; D019587:Dietary Supplements; D004435:Eating; D008297:Male; D008715:Methionine / Q000008:administration & dosage / Q000378:metabolism; D009584:Nitrogen / Q000032:analysis; D011897:Random Allocation; D030262:Soybean Proteins / Q000008:administration & dosage* / Q000378:metabolism; D013912:Threonine / Q000008:administration & dosage / Q000378:metabolism
chemical_list: D004044:Dietary Proteins; D030262:Soybean Proteins; D013912:Threonine; D008715:Methionine; D009584:Nitrogen