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Effects of feeding dried distiller grains with solubles (DDGS) to immunologically castrated pigs harvested at 5, 7, or 9 weeks post-second dose of Improvest on lean quality
Studies have shown feeding diets containing DDGS to growing-finishing pigs has minimal effects on lean quality of barrows and gilts, but lean quality of immunologically castrated pigs fed DDGS (10.4% crude fat) has not been evaluated. Entire male pigs were weighed at 8 weeks of age (WOA), assigned randomly to dietary treatments, and harvested at 9 (TD9), 7 (TD7), or 5 (TD5) weeks post-second dose of Improvest (gonadotropin releasing factor analog - diphtheria toxoid conjugate; Zoetis, Inc., Florham Park, NJ) in a 4 x 3 factorial arrangement. A 4-phase feeding program (phase 1 for 3 weeks, phases 2 and 3 for 4 weeks each, and phase 4 for 5 weeks) was used for each dietary treatment: positive control (PCon; 0% DDGS in all dietary phases), DDGS step down (SD; 40%, 30%, 20%, and 10% DDGS in the 4 dietary phases, respectively), DDGS withdrawal (WD; 40% DDGS in phases 1 to 3, and 0% DDGS in phase 4), and negative control (NCon; 40% DDGS in all dietary phases). All pigs received the first subcutaneous injection of Improvest at 11 WOA, and the second Improvest dose at 15, 17, or 19 WOA. At 13 WOA, 2 pigs/pen (n = 8 pens/treatment) were randomly selected for harvest at 24 WOA for carcass lean quality measurements at the University of Minnesota Meat Science Laboratory. Harvest day post-second Improvest dose did not affect pH at 48-hour postmortem, objective Hunter color, and subjective lean color scores of the longissimus muscle (LM). Pigs fed PCon tended (P < 0.10) to have lower LM pH at 45-min (6.15 vs. 6.29 ± 0.06) than pigs fed NCon, but by 48-h postmortem, pH was not different among dietary treatments. Drip loss of loin chops and purge loss of loin roasts were not different among dietary treatments. Dietary treatment had no effect on LM L*, but pigs fed PCon had higher (P ≤ 0.05) LM a*(-1.51 vs. -2.02 ± 0.12), and tended (P ≤ 0.10) to have higher LM b* (5.60 vs. 5.13 ± 0.68) compared with pigs fed NCon. Subjective firmness score of loins from pigs fed PCon was greater (P ≤ 0.05) compared with loins from pigs fed WD and NCon (2.60 vs. 2.28 and 2.24 ± 0.12, respectively). Dietary treatment and day of harvest post-second dose of Improvest had minimal effects on lean quality of pork, except for subjective LM firmness.
Keywords: DDGS, Improvest, lean quality