Digestibility of protein enriched citrus by-products for pigs

Abstract

Protein-enriched (by solid state fermentation) citrus by-products (PEC), containing 21.1% crude protein (CP) on a dry basis, was evaluated for effects on ileal and total tract digestibility. In two complimentary trials either three ileorectostomized or six intact pigs (60 kg liveweight) were fed increasing levels of PEC (0, 9.9 and 19.8%), which partially replaced high-test sugarcane molasses and soybean meal in the basal diet. Daily feed intake was fixed at 80 g of dry matter (DM) per kg W^0.75. Dietary treatments did not significantly affect ideal digestibility, but total tract digestibility of DM, organic matter, energy and PC declined as PEC levels increased, while that crude fiber was highest at the 9.9% PEC level. In vitro CP digestibility of PEC was 70.8%, while in vivo ileal and total digestibilities, estimated by difference, were 70.0 and 58.6%, respectively. The data indicate that protein and other non-fibrous nutrients supplied by PEC are well utilized in the anterior porcine digestive tract, but less well in the large intestine than as regards the basal diet. In spite of this limitation, PEC could contribute to swine feeding