Digestibility and availability of protein and phosphorus in pigs fed wet barley protein and wet distillers solids from integrated starch-ethanol production

Abstract

The nutritive value of two high protein feeds from the integrated starch-ethanol production from barley, wet barley protein (WBP) and wet distillers solids (WDS) were studied in two experiments with pigs. In experiment 1 the apparent ileal and total tract digestibility of protein and ileal digestibility of amino acids were determined using six growing pigs fitted with a T-shaped cannula at the end of the ileum. In experiment 2 the apparent total tract digestibility and availability of protein and phosphorus were determined using nine finishing pigs. Experiments were carried out on different batches of feeds. Feeds were included in semi-purified diets as the only source of protein (experiments 1 and 2) and as the only source of phosphorus (experiment 2). WBP contained less protein and phosphorus than WDS (332 and 7.0 g kg −1 dry matter (DM) vs. 518 and 11.3 g kg −1 DM, respectively). The crude protein in WBP also contained less lysine (3.0 g 16 g −1 N) than the crude protein in WDS (3.9 g 16 g −1 N). The apparent ileal digestibility of protein and most of the amino acids were significantly higher for WBP than for WDS. The respective values were: for protein 83.6% and 79.9% ( P < 0.01), for lysine 84.7% and 80.5% ( P < 0.01), for methionine 91.6% and 85.5% ( P < 0.001), for cystine 85.1% and 79.6% ( P < 0.001) and for threonine 80.1% and 74.3% ( P < 0.01). Similarly the feeds also differed in the apparent total tract digestibility of protein. Pigs retained more nitrogen after feeding on lysine-supplemented diets containing WDS than on those containing WBP. Phosphorus availability tended to be higher for WDS diets than for WBP diets (42.3% vs. 33.2%, P < 0.10) and accordingly differed in its retention in pigs ( P < 0.05).