Effect of supplemental iron on finishing swine performance, carcass characteristics, and pork quality during retail display

¹ Department of Animal Sciences, University of Arkansas, Fayetteville 72701
² Zinpro Corporation, Eden Prairie, MN 55334

^* To whom correspondence should be addressed. E-mail: japple{at}uark.edu.

	Abstract

Crossbred pigs (n = 185) were used to test the effects of dietary iron (Fe) supplementation on performance and carcass characteristics of growing-finishing swine. Pigs were blocked by BW, allotted to pens (5 to 6 pigs/pen), and pens (5 pens/block) were allotted randomly to either negative control (NC) corn-soybean meal grower and finisher diets devoid of Fe in the mineral premix, positive control (PC) corn-soybean meal grower and finisher diets with Fe included in the mineral premix, or the PC diets supplemented with 50, 100, or 150 ppm Fe from Availa-Fe (an Fe-amino acid complex). When the lightest block averaged 118.2 kg, pigs were slaughtered, and bone-in pork loins were collected during fabrication for pork quality data collection. During the grower-I phase, there was a tendency for supplemental Fe to reduce ADG linearly (P = 0.10), whereas, in the grower-II phase, supplemental Fe tended to increase ADG linearly (P = 0.10). Even though pigs fed NC had greater G:F during the finisher-I phase (P < 0.05) and across the entire trial (P = 0.07), live performance did not (P 0.13) differ among dietary treatments. There were linear increases in 10^th rib fat depth (P = 0.08) and calculated fat-free lean yield (P = 0.06); otherwise, dietary Fe did not (P > 0.19) affect pork carcass muscling or fatness. Moreover, LM concentrations of total, heme, and nonheme Fe were similar (P > 0.23) among treatments. A randomly selected subset of loins from each treatment were further fabricated into 2.5-cm-thick LM chops, placed on styrofoam trays, overwrapped with PVC film, and placed in coffin-chest display cases (2.6°C) under continuous fluorescent lighting (1,600 lux) for 7 d. During display, chops from NC-fed pigs and pigs fed diets supplemented with 100 ppm Fe tended to have a more vivid (higher chroma value; P = 0.07), redder (higher a* value; P = 0.09) color than LM chops of pigs fed 50 ppm of supplemental Fe. Moreover, greater (P < 0.01) a*-to-b* ratios in chops from pigs supplemented with 100 ppm Fe indicated a more red color than chops from PC-fed pigs or pigs fed diets supplemented with 50 ppm Fe. In conclusion, however, increasing dietary Fe had no appreciable effects on performance, carcass, or loin characteristics, suggesting that current dietary Fe recommendations are sufficient for optimal growth performance, pork carcass composition, and pork quality.

Key Words: Growth, Iron, Pork, Meat quality, Carcass composition, Retail display