Effect of Gender (Gilt, Surgically- and Immuno-Castrated Male) and Ractopamine Hydrochloride Supplementation on Growth Performance, Carcass and Pork Quality Characteristics of Finishing Pigs under Commercial Conditions

November 13, 2013 — 

This study evaluated the effects of gender and feeding of ractopamine on growth performance, carcass and meat quality characteristics of pigs reared under commercial conditions. The study was carried out as a Randomized Complete Block Design (blocking factor date of start on test) with a 3 x 2 factorial arrangement of treatments: 1) Gender [gilt (G) vs. surgical castrate (SC) vs. intact males immuno-castrate (IC)]; 2) Ractopamine level (0 vs. 5 ppm). The study was conducted out over a fixed duration (126 d) from 1 wk post weaning (28 d of age; 8.04 � 1.31 kg BW) to 154 d of age (111.44 � 4.67 kg BW) in 3 growth periods: nursery (d 0 to 35 of the study), growing (d 35 to 70), and finishing (d 70 to 126). Ractopamine was fed for the final 28 d of the study (d 98 to 126). Pigs were kept in groups of 10 or 11 in the nursery phase, and then moved to the growing-finishing facility where they were kept in groups of 22 to the end of the study. At the end of the growth study, pigs were harvested and carcass and pork quality were evaluated, including consumer evaluation of eating quality. During the nursery, there was no effect of gender (P > 0.05) on G:F, but SC grew faster (P < 0.05) than intact males and G and had greater (P < 0.05) ADFI than IC. There was no effect of gender (P > 0.05) on ADG in the growing period; however, IC had lower ADFI than SC and greater G:F than SC and G. In finishing, IC and SC had similar ADG but grew faster than G; G:F was greater for IC than the other genders. Feeding 5 compared to 0 ppm ractopamine increased ADG, and G:F but had no effect (P > 0.05) on carcass yield or fresh meat quality. Carcass yield was lower but percentage lean cut yield was greater for IC than for SC. Longissimus muscle drip loss was greater (P = 0.05) for IC than SC. Gender had no effect (P > 0.05) on consumer panel evaluation. Feeding ractopamine had no effect on pork flavor and tenderness but improved juiciness scores. Odor scores were similar (P > 0.05) for SC and IC that were fed ractopamine. Consumers gave lower liking scores for odor for IC than SC that were not fed ractopamine. This study highlights the feed efficiency and lean cut yield advantage for IC compared to SC and suggests a similar growth response to feeding ractopamine in these genders. While IC had a lower carcass yield, and higher drip loss, panelists were not able to detect differences in pork juiciness, flavor, and tenderness when compared to SC pigs.

D. V. Bra�a, G. A. Rojo Gomez, M Ellis, and J. A. Cuaron; Effect of Gender (Gilt, Surgically- and Immuno-Castrated Male) and Ractopamine Hydrochloride Supplementation on Growth Performance, Carcass and Pork Quality Characteristics of Finishing Pigs under Commercial Conditions; J ANIM SCI jas.2013-6546; published ahead of print October 1, 2013, doi:10.2527/jas.2013-6546 http://www.journalofanimalscience.org/content/early/2013/10/01/jas.2013-6546.abstract