The nutritive value of subterranean clover (Trifolium subterraneum L.), rose clover (Trifolium hirtum All.) and soft brome grass (Bromus mollis L.)

Abstract

Medium Peppin Merino wethers were fed, ad libitum, subterranean clover (cv. Woogenellup), rose clover (cv. Kondinin) and soft brome grass cut in September (spring), November (late spring) and January-February (summer). The nitrogen contents of the subterranean clover ranged from 1.89 to 3.13%, of the rose clover from 1.62 to 2.84% and of the soft brome from 0.42 to 2.86%. Mean daily organic matter intakes (kg) in spring, late spring and summer were respectively: for subterranean clover 0.78, 1.09 and 0.42; for rose clover 0.60, 0.87 and 0.62; for soft brome grass 0.87, 0.81 and 0.20. Organic matter digestibilities in spring, late spring and summer were, respectively: for subterranean clover 0.82 ,0.69 and 0.61; for rose lover 0.80, 0.62 and 0.54; for soft brome 0.83, 0.72 and 0.58. There were highly significant differences ( P < 0.001) in nitrogen balance between seasons. The estimated digestible energy intakes (MJ/day) in spring, late spring and summer were, respectively: for subterranean clover 12.7, 14.5 and 4.9; for rose clover, 9.2, 9.9 and 6.9; for soft brome, 13.6, 10.1 and 2.1. Within seasons there were significant (P < 0.05) differences in nitrogen balance between species. There were significant differences between species in mean retention time in the alimentary tract in late spring (P<0.001) and summer (P<0.001) but not in spring. There was a highly significant negative relationship between acid-detergent fibre content and both organic matter and fibre digestibilities. The superior digestible energy intakes of the 2 clovers explain at least some of the superior performance of sheep grazing clover compared with those grazing grass pastures.