Journal of Animal Science, Vol 73, Issue 3 799-804, Copyright © 1995 by American Society of Animal Science

JOURNAL ARTICLE

Copper bioavailability in pork liver and in various animal by-products as determined by chick bioassay

S. Aoyagi, K. M. Hiney and D. H. Baker
Department of Animal Sciences, University of Illinois, Urbana 61801, USA.

Three chick experiments were conducted to investigate possible explanations for why pork liver provides no bioavailable Cu to chicks. Autoclaving, acid-hydrolysis, and protease-digestion increased (P < .01) Cu bioavailability in pork liver to 32, 46, and 63%, respectively, from virtually 0% of the Cu in unprocessed pork liver (relative to CuSO4, which was set at 100%). Addition of EDTA at 200 mg/kg to the diet containing 1 mg of Cu/kg from unprocessed pork liver also resulted in an increased (P < .07) Cu bioavailability, to 23%. Tissues representing different sources of endogenous Cu in the pig also were evaluated for their Cu bioefficacy. Freeze-dried (FD) porcine bile did not have any bioavailable Cu, whereas spray-dried porcine plasma contained Cu that was as available (99%) as that in CuSO4. In addition, when FD pork liver or FD porcine bile was added to the basal diet containing .5 mg of Cu/kg from CuSO4, Cu bioavailability in CuSO4 was reduced (P < .05) to 34% and 19%, respectively, of values obtained with CuSO4 alone. An additional experiment was conducted to estimate Cu bioefficacy in selected animal-source feed ingredients. Copper bioavailability in all-beef meat and bone meal, all-pork meat and bone meal, mixed-species meat and bone meal, high-bone meat and bone meal, poultry byproduct meal, and hog hair meal was 4, 53, 28, 8, 42, and 9%, respectively, relative to CuSO4. Feather meal did not provide any bioavailable Cu to chicks.