Growth performance, carcass characteristics, plasma minerals, and fecal mineral excretion in grower-finisher swine fed diets with levels of trace minerals lower than common industry levels

Abstract

Objectives: To determine the impact of lowering levels of supplemental trace minerals (TM) below those commonly fed to grower-finisher swine on fecal mineral excretion, growth performance, carcass characteristics, and economic return. Methods: Pigs (n = 6024) were randomly distributed into four blocks of two barns per block and allotted within block to diets with either Normal (industry levels) or Reduced TM supplementation. Growth performance was measured for each barn, and individual carcass characteristics were recorded at a commercial packing plant. Fecal samples randomly obtained from at least eight pigs per barn were analyzed for zinc, copper, iron, and manganese. Plasma samples from six pigs per barn were analyzed for zinc, copper, and iron. Results: In pigs fed Reduced TM diets, fecal levels were lower for zinc (P < .05), and tended to be lower for copper, iron, and manganese (P < .10), than in pigs fed Normal TM diets. Carcass weight, carcass weight payment, and total payment were greater for pigs fed Reduced TM diets (P < .05), which may have been partly due to greater weight at placement and uneven gender distribution. Backfat thickness, loin depth, percent lean, and lean premium payment did not differ between treatments (P > .05). Implications: Fecal excretion of zinc was significantly lower, and excretion of copper, iron, and manganese tended to be lower, in grower-finisher pigs fed diets containing trace mineral levels lower than common industry standards. Carcass characteristics were not negatively affected.