The nutritive value of new zealand tall-tussocks (chionochloa) fed to sheep

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Abstract
Single-species digestibility trials were performed on four species of New Zealand tall-tussock (Chionochloa macra, C. rigida, C. flavescens, and C. rubra) when fed alone except for access to ad lib. mineral lick and when fed with a lucerne supplement. When fed alone, average ad lib. intakes for the four species ranged from 340–430 g per day. The mean digestibility coefficients were for organic matter 44–59, for cellulose 46–74, and for hemicellulose 50–62, but the coefficients for nitrogen were extremely low except for C. rigida. Sheep eating C. macra and C. rubra were in negative nitrogen balance. Voluntary feed intake and overall utilisation of all species were probably limited by the lack of nitrogen available for bacterial growth in the rumen. Supplementation of each species with high-protein lucerne cubes (100 g per day) gave significant increases in intake of each species, mean intakes ranging from 476–733 g per day. The digestibility coefficients of the combined tussock plus lucerne diet for organic matter (42–58), cellulose (58–74), and hemicellulose (45–64) were similar to those obtained with tussock alone, but coefficients for nitrogen (41–49) increased markedly. Supplementation of tussock with lucerne resulted in digestible organic matter intakes increasing from approximately one-third to one-half maintenance on the tussock only diets to at least two-thirds maintenance on the supplemented diets. The descending order of intakes of tussock herbage was C. macra, C. rubra, C. rigida, and C. flavescens. For the digestibility of dry matter, organic matter, hemicellulose, and cellulose the reverse order trend was shown. No clear evidence was obtained that these rankings were affected by lucerne supplementation. Application of these results to field conditions is discussed, in particular the deficiencies of nitrogen and mineral in tussock herbage.