THE INFLUENCE OF SEX ON THE RESPONSE OF SELF-FED PIGS TO RATION DILUTION DURING THE FINISHING PERIOD

Abstract

Two replicated experiments, involving 256 Yorkshire pigs, were conducted to determine the response of barrows and gilts to dilution of finishing rations. In the first experiment an oat–barley basal ration was diluted with 10% increments of a mixture of alfalfa meal and ground oat hulls. In the second, a wheat–barley basal ration was diluted with 15% increments of each of two diluents, an alfalfa meal – oat hull mixture and ground oat hulls alone.In both experiments, rate of gain of barrows was more adversely affected than that of gilts as the level of ration dilution increased. Dilution of the oat–barley basal ration at the 50% level reduced daily gains of gilts and barrows by 26 and 44% respectively. When the wheat–barley basal ration was diluted with 45% of the mixed diluent, daily gains of gilts were improved slightly while those of the barrows were reduced by 15%. When the oat hull diluent was used at the 45% level, daily gains of gilts and barrows were reduced by 4 and 18% respectively when compared with controls fed no diluent.The alfalfa meal – oat hull diluent, added to the wheat–barley ration, increased the proportion of A grades in barrows and gilts; when added to the oat–barley ration the only improvement occurred with barrows. The oat hull diluent had little effect on carcass grades.