Addition of different sources and levels of amino acids and sugars to broiler litter before deep-stacking

Different sources and levels of amino acids (soybean meal at 0, 10, 20 or 40% of dry matter; similar quantities of lysine and methionine in synthetic forms) and sugars were mixed with broiler litter and placed in dacron bags embedded in a deep-stack for 3 or 9 weeks to determine changes in concentrations of nitrogen fractions and digestibility in ruminants. Pepsin-insoluble nitrogen concentration after 48 h of ruminal incubation was not changed by deep-stacking for 3 wk and only slightly elevated at 9 wk. Deep-stacking did not markedly alter in situ ruminal disappearance of broiler litter nitrogen. Conversely, in situ ruminal nitrogen disappearance of soybean meal substrates was decreased by deep-stacking; the change was greater for 16 than for 48 h of ruminal incubation. Sugar addition to soybean meal substrates did not appear to enhance rumen undegradable protein concentration. In conclusion, these results suggest that potential exists to markedly increase rumen undegradable protein in soybean meal and possibly other feedstuffs high in rumen digestible protein by addition to broiler litter before deep-stacking.