SUPPLEMENTAL COPPER FOR SWINE: GROWTH, DIGESTIBILITY AND CARCASS MEASUREMENTS

Abstract

Four experiments were conducted with a total of 144 pigs to study the effects on rate of gain, efficiency of feed utilization, digestibility and retention of nutrients and carcass characteristics of adding 0.10% CuSO4∙5H2O to the diets of crossbred pigs, fed ad libitum or restricted to scale, from weaning to market weight. The diets contained either fishmeal or soybean meal as protein supplements and were formulated to contain 14 or 17% protein. For ad libitum-fed pigs, the addition of copper to the diet improved rate of gain by 6.2% and efficiency of feed utilization by 3.8% up to 50 kg liveweight, with a lesser improvement for restricted pigs. The increased gain and reduced feed per kg gain with copper supplements were more apparent when fishmeal rather than soybean meal and a high rather than a low protein level were fed. Rate of gain and efficiency of feed utilization were increased only slightly by copper supplements when the overall growth period to market weight was considered. In digestibility studies, chromium sesquioxide as an indicator and total fecal collection gave comparable results, but digestibility coefficients were higher when the total collection method was used. Energy digestibility and nitrogen digestibility and retention were not consistently influenced by supplemental copper. Metabolizable energy was not altered by supplemental copper in the diet. The carcasses of ad libitum-fed pigs receiving supplemental copper with high protein were generally lower in backfat, and had larger cross-sectional areas of the loin and higher carcass ROP scores, than those receiving no supplemental copper. However, pigs fed ad libitum copper-supplemented diets containing fishmeal yielded a large proportion of carcasses with soft fat. This softer consistency of fat was less apparent in carcasses of pigs fed soybean meal and did not occur at market weight in pigs fed diets restricted to scale.