Effects of copper sulfate and ferrous sulfide on performance and liver copper and iron stores of pigs.

Three experiments involving 296 pigs were conducted to determine the related effects of copper sulfate and ferrous sulfide on performance and liver copper and iron stores of growing-finishing pigs, and the effect of ferrous sulfide on the depletion of copper from the liver. The dietary addition of 250 ppm copper alone improved growth rate by 9.2% (621 vs 678 g/day) and feed to gain ratio by 3.3% (3.06 vs 2.96) to 56 kg body weight. Growth rate to 94 kg body weight was increased 4.4% (689 vs 719 g/day) and feed to gain ratio decreased by 2.2% (3.22 vs 3.15). Feeding sulfide as ferrous sulfide at O, 500, 1,000 or 2,000 ppm resulted in a linear decrease in daily gain. The beneficial growth response to copper was maintained at the 500 ppm level of sulfide addition but growth was depressed at higher levels. Liver copper levels were increased approximately 15fold by feeding 250 ppm copper. Adding graded levels of sulfide resulted in a quadratic decrease in the accumulation of copper in the liver. Liver copper levels of pigs fed 250 ppm copper and 500, 1,000 or 2,000 ppm sulfide were approximately 2.7, 1.7 and 1.4 times greater, respectively, than those of control pigs. Liver iron content of pigs fed 250 ppm copper was approximately one-half that found in livers of control pigs. Addit ion of ferrous sulfide to the high copper diets resulted in liver iron levels that were slightly higher than those of control pigs. Dietary addition of 500 ppm copper for 63 days resulted in high liver copper levels