RELATIVE BIOAVAILABILITY OF COPPER IN A COPPER-LYSINE COMPLEX OR COPPER-SULFATE FOR RUMINANTS AS AFFECTED BY FEEDING REGIMEN

An experiment was conducted with 40 crossbred wether lambs to compare the relative bioavailability of Cu from a Cu-lysine complex with that from Cu sulfate under two feeding regimens, Liver biopsy samples were collected by a laparotomy technique and lambs were given 12 days to re cover and adapt to individual pens. Lambs were fed either a control ba sal diet (9.8 mg kg(-1) Cu dry matter (DM) basis) or basal supplemente d with 180 mg kg(-1) Cu as either reagent grade CuSO4 . 5H(2)O or a fe ed-grade Cu-lysine complex. There were 12 lambs fed control diet and 1 4 lambs fed each Cu-supplemented diet. Half of the lambs given each di et were fed 1.0 kg of their respective diet once daily at 08:00 h, The remaining half were fed 1.0 kg in equal portions (166 g) six times du ring a 24 h period at 04:00 h, 08:00 h, 12:00 h, 16:00 h, 20:00 h and 24:00 h. Lambs were fed experimental diets for 10 days, then killed an d livers removed for Cu analysis, Lambs fed once daily accumulated mor e (P < 0.05) Cu in liver than those fed every 4 h. There was no Cu sou rce X feeding regimen interaction (P > 0.10). Based on multiple linear regression slope ratio of log(10) transformed final liver Cu concentr ation on total intake of Cu (mg day(-1)) with the initial liver biopsy Cu concentration as a covariate, bioavailability of Cu from Cu-lysine relative to Cu sulfate was 93.4% (P > 0.05) for combined feeding regi mens.