Three experiments were conducted to determine the effect of incremental levels of red blood cells (RBC; 0 to 4%, Exp. 1; 0 to 2%, Exp. 2 and 3) on growth performance and carcass traits of finishing pigs. Dietary treatments were formulated to meet or exceed the nutrient requirements of barrows and gilts gaining 350 g of lean BW gain per day and were formulated to contain 0.52% apparent ileal digestible (AID) Lys for barrows and 0.59% AID Lys for gilts. In Exp. 1, barrows and gilts (2 replicates of barrows and 2 of gilts; 4 pigs per pen) were fed 0, 1, 2, 3, or 4% RBC. Initial BW (mean was 84.6 and 82.42) and final BW was 118.7 and 120.0kg for barrows and gilts, respectively. Two barrows and 2 gilts per pen were randomly selected and slaughtered for collection of carcass measurements. Experiment 2 was similar to Exp. 1, except 0, 1, or 2% RBC were added. Initial BW was 82.5 and 79.2kg, and final BW was 125.5 and 119.8kg for barrows and gilts, respectively. Each dietary treatment had 4 replicates per sex with 4 pigs per pen. One barrow and 1 gilt per treatment replicate were randomly selected and slaughtered for collection of carcass traits and viscera weights. Experiment 3 was similar to Exp. 2 except only barrows were used, and the initial and final BW were 86.0 and 133.4 kg, respectively. Each dietary treatment had 4 replicates with 3 pigs per pen, and all pigs were slaughtered for collection of carcass traits and viscera weights. In Exp. 1, final BW, ADG, and G:F were decreased linearly as RBC addition increased, but ADFI was not affected. With increased RBC addition, average backfat increased and fat free lean decreased. There was a quadratic effect on dressing percentage (DP); the 2% RBC addition increased DP, but the 3 and 4% additions decreased DP. The RBC addition had no effect on any remaining carcass measurements. In Exp. 2, there was a quadratic effect of RBC addition on average backfat; the 1% RBC addition decreased backfat, but the 2% addition returned backfat to the level of the control pigs. There was no effect on any other response variable. In Exp. 3, with increased RBC addition, average backfat linearly decreased and large intestine percentage increased. There was no effect of RBC addition on any other response variable. Our data indicate that feeding 3 or 4% RBC decreases growth performance of finishing pigs. However, feeding 1 or 2% RBC to finishing pigs had no detrimental effects on growth performance and increased DP in one experiment. 

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