Effects of dietary copper sulfate on the fatty acid composition of porcine depot fats.

C ONSISTENCY of carcass fat may be a factor in pork quality (Harrington, 1958). Barber et al. (1957) and Beltis (1961) reported that dietary copper supplements adversely affected the carcass grades of market pigs. Taylor and Thomke (1964) observed that copper supplementation of the diet resulted in a softening of the depot fat as indicated by a significantly (P < .01 ) greater iodine value (Hanus) and a significantly (P< .01 ) decreased consistency value. The latter value is expressed as the amount of vacuum required to extract a sample of fat from a tube under defined conditions as described by Taylor and Thomke (1964). However, Braude (1965) reported that an attempt to confirm this observation was unsuccessful. Experiments at the University of Alberta support the report of Taylor and Thomke (1964). Soft fat was noted on the grading reports of 80% of 40 market pigs receiving copper (CuSO4"5H,)O to supply approximately 250 mg. Cu/kg. diet) as a supplement to barley-fishmeal diets. Of these 32 pigs with soft fat, 52% were degraded for this reason alone under Canadian hog carcass grading standards. Only 5% of pigs fed the same dietary formulation without copper supplement had soft fat. When copper was added to barley-soybean meal diets 19% of the pigs were reported to have soft fat. No soft fat was reported among pigs fed the unsupplemented soybean meal diets. Other aspects of these experiments are published elsewhere (Bowland and Castell, t964, 1965). The experiment reported herein was designed to obtain information concerning the effects of copper supplementation of a barleyfishmeal diet on the fatty acid composition of the depot fat of market pigs.