Recovery of pasture seed ingested by ruminants. 2. Digestion of seed in sacco and in vitro

Abstract

Seeds of the grasses Brachiaria decumbens (signal grass) and Axonopus afinis (carpet grass), and the legumes Neonotonia wightii cv. Tinaroo, Trifolium semipilosum cv. Safari, Stylosanthes hamata cv. Verano and S. scabra cv. Seca were suspended in nylon bags in the rumen ofcattle (in sacco) and also subjected to in vitro digestion techniques. Legume seeds were evaluated in 3 categories: seed as supplied (mixture of hard and soft), 100% soft and 100% hard. Seeds were either placed in the rumen of cattle (using nylon bags) for 24, 48 or 96 h or subjected to in vitro digestion (in pepsin, and in rumen liquor or cellulase either with or without subsequent digestion in pepsin). Other seed of the same seed lots had been previously fed to penned cattle, sheep and goats and the recovery in faeces had been measured. Soft legume seed were destroyed by the digestion treatments whereas hard seeds were largely resistant to digestion. Average effects of digestion in vitro on viability were similar to average effects of digestion in nylon bags, but there were large differences between different treatments and between seed lots. The percentage of hard seed in the seed sample was the best guide to the resistance of legume seed to digestion.