RELATIVE BIOAVAILABILITY OF COPPER IN A COPPER LYSINE COMPLEX FOR CHICKS AND LAMBS

Two experiments were conducted to study the relative bioavailability o f Cu in a Cu-lysine complex with that of reagent grade CuSO4.5H2O for chicks and lambs. Chicks were fed a basal diet (11 mg kg-1 Cu, dry mat ter (DM) basis) or the basal diet supplemented with 150, 300 or 450 mg kg-1 Cu from either of the two Cu sources for 18 days. Birds were kil led and liver Cu concentrations determined. Liver biopsy samples were collected from wether lambs who were then fed the basal diet (9.5 mg k g-1 Cu DM) or the basal diet supplemented with 60, 120 or 180 mg kg-1 Cu from either source for 10 days. Copper in the initial biopsy was us ed as a covariate in the multiple linear regression of log10 final liv er Cu concentration on added dietary Cu concentration. Slope ratio com parisons gave relative Cu bioavailability values of 99 and 68 for Cu-l ysine in chicks and lambs, respectively, compared with 100 for CUSO4.5 H2O for both species.