STUDIES IN THE DIGESTIBILITY OF HERBAGE

Abstract

This paper presents the results of 125 digestion trials with sheep fed herbage at different stages of growth from three clover‐free pure grass swards. During 1958 and 1959, a study was made of the yield, leaf lamina, nitrogen, ash and digestible organic matter percentage ( D ) of first growths, of regrowths cut at monthly and two monthly intervals and of swards receiving various quantities of fertilizer nitrogen. For first growths in the spring D remained almost constant until the ears started to protrude from the leaf sheaths and then fell rapidly at approximately 0·5 per cent per day. The D values for S 23 ryegrass were three weeks later than S 24 ryegrass, which correspond with later ear emergence of the latter. S 37 cocksfoot was always less digestible than S 24 ryegrass although both were at similar stages of growth. This difference in D also occurred in the regrowths. The D of monthly regrowths tended to fall with each successive cut, although in 1959 ryegrass values improved in the autumn. Fertilizer nitrogen had little effect on D . Despite the warmer spring and drier summer in 1959 and corresponding changes in production per acre there was little effect on D .