Meat and bone meals incorporated at two levels in grower-pig rations based on either sorghum of wheat

Two experiments are reported in which a total of 96 Large White pigs were individually fed from 21 to 74 kg bodyweight on rations based on either sorghum or wheat. In the first experiment the protein supplement consisted of 20 per cent of one of two meat and bone meals or 15 per cent soybean meal. The ration containing soybean meal was presented with or without added calcium and phosphorus to provide levels of these elements equal to those in one of the meat and bone meal rations. Pigs fed the wheat-based rations had 13 per cent (P<0.05) greater growth rates and utilized feed 7 per cent more efficiently than those fed the sorghum-based rations. The rations containing the meat and bone meals produced 10 per cent lower growth rates and were utilized less efficiently (P<0.05) than those containing soybean meal. The addition of calcium and phosphorus to the soybean meal rations had no significant effect on growth. Ration composition had no effect on carcase measurements. In the second experiment the rations were based on either sorghum or wheat and were supplemented with either 15 per cent or 20 per cent of one of two meat and bone meals. Pigs fed the wheat-based rations had 11 per cent (P<0.05) greater growth rates and utilized feed 11 per cent more efficiently than those fed the sorghum-based rations. The efficiency of feed utilization for pigs fed the 20 per cent level of meat and bone meal was 5 per cent greater than that of pigs fed the 15 per cent level below 45 kg bodyweight but not above this weight. Growth rate was not significantly affected by level of meat and bone meal. Feed efficiency was greater for rations containing the, meat and bone meal with the lower ash content. The only treatment that affected carcase measurements was the level of meat and bone meal in the ration. Pigs fed the rations with 20 per cent meat and bone meal produced carcases with 11 mm of backfat (not including the skin) above the last rib, whereas those fed the 15 per cent level had 13 mm of backfat.