Interaction of dietary nutrient concentration and supplemental copper on chick performance and tissue copper concentrations.

An experiment was conducted with 576 female Cobb feather-sexed chicks to study the influence of methionine (MET) and selected nutrient (SN) supplementation on the performance of chicks fed high Cu levels. Day-old chicks were allotted randomly to pens for the 22-day experiment. A 3 X 2 X 2 factorial arrangement of treatments was used which included Cu at 0, 400, and 800 mg/kg, MET at 0 and .4%, and SN at 0 and 20%. A significant (P less than .001) Cu X MET X SN interaction was found for gain. Supplemental MET reversed the growth depression observed in birds fed 400 but not 800 mg/kg Cu. Additions of 400 and 800 mg/kg Cu to the basal diet depressed (P less than .001) feed consumption by 8.6 and 19.4%, respectively. Hepatic Cu concentrations increased linearly (P less than .001) with increasing dietary Cu and were not influenced (P greater than .10) by supplemental MET or SN. Liver weights increased linearly (P less than .001) with increasing dietary Cu and were higher (P less than .05) for chicks on diets supplemented with SN, but lower (P less than .05) for those with diets supplemented with MET. The interaction of MET X SN was significant (P less than .001) for serum Cu; chicks supplemented with SN in conjunction with MET had the lowest (P less than .05) serum Cu concentrations. Serum glutamic-oxaloacetic transaminase (SGOT) activity was not influenced (P greater than .10) by dietary Cu, but SN supplementation resulted in a 10% elevation (P less than .001) in SGOT activity.(ABSTRACT TRUNCATED AT 250 WORDS)