291 Determining the effects of manganese source and level on growth performance, carcass characteristics, and economics of growing-finishing pigs

Abstract A total of 1,944 pigs (PIC 337×1050; initially 34.5±0.50 kg) were used in a 107-d growth trial to determine two different manganese source at 3 doses level effects on performance of growing-finishing pigs. Pens (27 pigs) were assigned to treatments in a RCB based on weight with 12 replicates/treatment. Diets were corn-SBM-based and fed in 4 phases. Treatments were arranged in a 2×3 factorial with Mn source (MnSO4 or Mn hydroxychloride: IBM, Micronutrients, Indianapolis, IN) and level (8, 16, or 32 ppm) as main effects. Overall, there was a marginal Mn source×level interaction (quadratic, R=0.057) for G:F, with the lowest and highest level of Mn IBM being best, but G:F improved with increasing Mn from MnSO4. There was no evidence for Mn source differences for ADG or ADFI, but 16 ppm of Mn tended to have the poorest (quadratic, R< 0.097) ADG and final BW (quadratic, R< 0.05) compared to other levels. There was a tendency for Mn source′level interaction (quadratic, R=0.075) for carcass yield, where yield did not change by increasing MnSO4, but was greatest for 16 ppm Mn from IBM. Loin depth increased (source×level, R=0.041) for increasing Mn from MnSO4 but decreased when Mn was increased from IBM. The intermediate level of Mn had the lightest HCW (quadratic, R=0.071) and decreased loin depth (quadratic, R=0.044). No evidence of difference (R >0.10) was observed for concentration of Cu and Zn in the liver. Manganese concentration increased (linear, R=0.015) as Mn supplementation increased and tended to be greater (P=0.075) when Mn was supplied by MnSO4 compared to IBM. These data suggest little difference between source but did show improvements in growth performance for 8 and 32 ppm of Mn compared with 16 ppm. Further research is needed to understand why the poorest performance was observed at the intermediate level of Mn.