EFFECTS OF DIETARY COMPOSITION ON THE RELATIVE PERFORMANCE AND CARCASS CHARACTERISTICS OF MALE AND FEMALE PIGS FED FROM 25 KG TO 92 KG LIVEWEIGHT

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Abstract
One hundred and twenty-four feeder pigs, representing two breed groups (Hampshire × Yorkshire and Yorkshire) were used in three experiments to compare the live performance and carcass characteristics of boars, barrows and gilts fed, from 25 to 92 kg, a 16% protein, barley–soybean meal diet or diets based on a utility grade, soft wheat (Triticum aestivum cv. Pitic 62) with 0, 7½ and 15% field peas (Pisum sativum cv. Century) to provide total protein levels of 13, 14 or 15%. Under conditions of adequate nutrition, boars were superior to barrows in efficiency of feed conversion and estimates of carcass leanness, while gilts were intermediate in feed conversion and equivalent to boars in carcass indices. The amount and composition of the diet consumed had a greater effect upon the relative performance of boars and, to a lesser extent, of gilts than was observed with barrows. In addition, the dressing percentage was consistently lower with boars than with barrows or gilts. Sexual odor or taint was not noticeably present in the carcasses at the packing plant, although there was a tendency for meat from boars on restricted feeding to have a higher moisture and darker lean than that present in carcasses from barrows and gilts. The results also suggested that satisfactory performance of growing–finishing pigs could be achieved with diets based on Pitic 62 wheat using field peas as the sole source of supplementary protein.