The efficiency of wool production of grazing Merino sheep

Abstract

The comparative efficiencies of wool production of a fine-wool and a strong-wool strain of Merino sheep have been studied at pasture. At pasture, the strong-wool strain, although only 22 per cent. heavier in body weight, produced 39 per cent. more clean fleece. It was calculated, with the use of faecal output data. that the strong-wool strain consumed 17 per cent. more feed and produced 19 per cent. more clean fleece per unit of feed consumed. The faeces of the strong-wool strain contained higher concentrations of nitrogen, total ash, and 'silica-free' ash and a lower concentration of crude fibre; this suggested that the feed selected by this strain was slightly higher in nutritive value. Significant differences between strains in digestive ability were sometimes observed, but they were small and inconsistent. It seems likely that, if real differences exist, they will be small. In pens, under controlled conditions of feeding, the strong-wool strain produced 18 per cent. more clean fleece per unit of feed consumed; the measured efficiency of wool production of individual sheep was significantly related to the estimated efficiency of these sheep at pasture. Wool production per unit of body weight may be a useful criterion for selecting efficient wool-producing sheep at pasture.