Abstract:
Twenty barrow and twenty gilt Berkshire x Large White pigs were fed barley based diets containing protein supplements of either 13 per cent soybean meal, 9 per cent fishmeal, 14.5 per cent safflower meal plus 0.2 per cent I-lysine mono hydrochloride plus 0.1 per cent methionine or 14.5 per cent safflower meal plus 4.5 per cent fishmeal from 46.4 to 87.0 kg liveweight. All diets were fed individually at a restricted feeding scale. The safflower meal diets were also fed ad libitum. Barrows and gilts fed ad libitum recorded a 65 and 27 per cent improvement respectively in average daily gain and had slightly fatter carcases than those fed comparable diets restrictively. Feed conversion ratio was not significantly affected by level of feeding. Growth and carcase attributes of pigs fed diets restrictively were similar apart from the feed conversion ratio of pigs fed the amino acid supplemented safflower meal diet, which was inferior (P < 0.05) to those fed the soybean meal supplemented diets. Barrows grew faster and produced fatter carcases than gilts, A significant sex x diet interaction occurred from which it was concluded that gilts, but not barrows, could be fed ad libitum without detriment to the quality of the carcase.