EFFECTS OF FEEDING LEVEL, PROTEIN LEVEL, AND SEX OF PIG ON CARCASS FATNESS MEASURED BY DISSECTION AND OPTICAL PROBE METHODS

384 pigs (entire males, females, and castrates in equal numbers) were slaughtered at either 80 or 100 kg liveweight, and were used to compare two methods of estimating the fat content of the carcass. The pigs were fed in a factorial arrangement on four different levels of intake and four diets of varying protein content. Despite the wide variation in carcass fat content so produced, measurements made using an optical probe were always closely related to measurements derived from the ‘fat trim’, i.e., the combined weight of dissected subcutaneous fat, cavity fat, skin, and cutaneous muscle. The fat content of the carcass was increased by high feed intakes and decreased by high protein levels. Interactions occurred between sex, feeding level, and protein level. The largest differences in fat content among the three groups were between entire males and castrates, particularly at high protein and low feeding levels. Females were intermediate in response.