Quantitative studies of the digestion of tropical and temperate forages by sheep

Abstract

Studies of the digestion by sheep of tropical grasses Digitaria decumbens and Setaria sphacelata and the temperate grass Lolium perenne grown at 27.5°S. latitude plus a clover Trifolium resupinatum grown in southern Australia are reported. There were no major differences between forages in the site of organic matter digestion, in protein flow from the stomach, in concentrations or proportions of rumen volatile fatty acids and in chewing behaviour between these data and the values generally reported for temperate forages of similar chemical composition and digestibility. However rumen ammonia concentrations for D. decumbens and S. sphacelata (53 and 34 mg N/L) were appreciably lower than predicted values of 108 and 131 mg N/L. Apart from this variable it appears that relationships developed with temperate feeds provide adequate prediction of digestive characteristics of tropical feeds.