Effect of ractopamine level, gender, and duration of ractopamine on belly and bacon quality traits

The objective was to determine belly and bacon quality traits in pigs fed ractopamine (RAC) for various durations during finishing. A 2 × 3 × 2 factorial arrangement was used with barrows and gilts, fed RAC levels of 0.0, 5.0, or 7.4 ppm, for 21 or 28 d prior to harvest. Bellies were fabricated and measured for length, thickness, firmness, and processing yields. Once processed, 1.27 cm slices were removed at 25%, 50%, and 75% the distance from the blade end, packaged and digitally imaged using a Chem1 Genius2 Bio Imaging System. Total slice area (TA), total slice length (TL), secondary lean length (SL), secondary lean area (SA), and percent lean area (TA – all lean components = LA) were determined by tracing images in Adobe Photoshop Elements. A composite sample from the three slices was used for proximate analysis to determine moisture and fat composition for each belly. Feeding RAC increased belly yield, TA, TL, SA, and LA (P < 0.05), but did not alter moisture or fat composition (P > 0.05). Gilts had decreased firmness and higher pump uptakes compared to barrows (P < 0.05). Additionally gilts had increased TL, SL, and LA with lower fat and higher moisture content (P < 0.05). RAC feeding duration had no significant effect on belly or bacon quality traits (P > 0.05), furthermore, no interactions were found to be significant (P > 0.05). RAC administration during finishing resulted in improved belly and bacon yields with no negative effects on the quality traits evaluated.