Effects of ractopamine hydrochloride on the growth performance and carcass characteristics of heavy-weight finishing pigs sent for slaughter using a 3-phase marketing strategy.

A total of 2,158 crossbred pigs was used to evaluate the effects of feeding 7.4 mg/kg ractopamine hydrochloride (RAC) on the growth performance and carcass characteristics of heavy-weight finishing pigs sent to slaughter using a 3-phase marketing strategy. The study was performed from 121.0 ± 4.28 kg to 144.5 ± 4.73 BW using a randomized complete block design (blocking factor was d of start on test) with 2 treatments (0 vs. 7.4 mg/kg RAC). Pigs were housed in a commercial wean-to-finish facility in groups of approximately 25 (44 groups/treatment), with ad libitum access to feed and water throughout the study, and pen weights of pigs were recorded at the start (d 0), and on d 7, 21, and 35 of study. Pigs were sent for slaughter according to the following marketing strategy: 1) after 7 d on RAC, the heaviest 16% of each pen was sent for slaughter (Phase 1), 2) after 21 d on RAC, the next 40% of each pen was sent for slaughter (Phase 2), and 3) after 35 d on RAC, the remaining 44% of each pen was sent for slaughter (Phase 3). Pigs were selected for slaughter by visual appraisal and shipped to a commercial facility where standard carcass measurements (HCW, LM depth, and backfat depth) were measured. Overall, feeding RAC increased (P < 0.001) ADG (18.8%) and G:F (23.7%) compared to the control, but lowered (P < 0.001) ADFI (3.3%). In addition, feeding RAC increased (P < 0.001) HCW (3.9 kg), carcass yield (0.7% units), LM depth (5.0%), and predicted lean content (1.0% units), and reduced backfat depth (6.3% lower) compared to controls. With each subsequent phase of marketing, the magnitude of improvements in response to feeding RAC decreased for ADG (43.1, 20.9, and -3.1% for Phase 1, 2, and 3, respectively) and G:F (37.5, 25.8, and 6.4% for Phase 1, 2, and 3, respectively); however, improvements in HCW (1.6, 4.5, and 4.2 kg for Phase 1, 2, and 3, respectively), carcass yield (0.2, 0.6, and 0.9% units for Phase 1, 2, and 3, respectively), LM depth (2.3, 5.7, and 5.2% for Phase 1, 2, and 3, respectively), and predicted lean content (0.2, 1.0, and 1.3% units for Phase 1, 2, and 3, respectively) generally increased from feeding RAC. These results suggest that while improvements in growth performance from feeding RAC will generally decline after 21 d of feeding, improvements in carcass traits, particularly carcass yield and lean content, will continue with feeding RAC until d 35.

Effect of narasin (Skycis) or zinc bacitracin (Albac) inclusion on the growth performance and carcass characteristics of finishing pigs sent for slaughter using a 3-phase marketing strategy.

The objective of this study was to evaluate the effect of dietary inclusion of narasin or zinc bacitracin on the growth performance and carcass characteristics of finishing pigs sent for slaughter using a 3-phase marketing strategy. The study used 2,219 crossbred pigs in a randomized complete block design (blocking factor = start date) with 3 dietary treatments: 1) Control (no feed additive), 2) 15 mg/kg narasin (Skycis, Elanco Animal Health, Greenfield, IN), and 3) 28 mg/kg zinc bacitracin (Albac, Zoetis, Parsippany, NJ). Pigs were housed in single-sex pens of 25 pigs in a commercial wean-to-finish facility and there were 30 pen-replicates of each dietary treatment. All pigs were weighed as a group (i.e., pen) on d 0 (start of experimental feeding period), 77, 91, and 105 (end) of study. Pigs had ad libitum access to feed and water throughout the study period; all feed additions to the feeder were recorded. Pigs were sent for slaughter according to the following marketing strategy: 1) after 77 d on study, the heaviest 20% of each pen was sent for slaughter (Phase 1), 2) after 91 d on study, the next heaviest 48% of each pen were sent for slaughter (Phase 2), and 3) after 105 d on study, the remaining 32% of each pen was sent for slaughter (Phase 3). Pigs within each pen were selected for slaughter by visual appraisal of weight and shipped to a commercial slaughter facility where standard carcass measurements (HCW, LM depth, and backfat depth) were measured. Feeding narasin increased (P < 0.05) final live BW (1.3 kg) and overall ADG (1.1%) compared to the other treatments, which were similar (P > 0.05). Dietary treatment did not impact (P > 0.05) overall G:F. Feeding narasin increased (P < 0.05) HCW (1.4 kg) and carcass yield (0.3% units) compared to the other dietary treatments, which were similar (P > 0.05) for these traits. Overall, these results demonstrate that narasin-fed pigs had improved overall growth rate, HCW, and carcass yield compared to controls or pigs fed zinc bacitracin.

Effect of corn dried distillers grains with solubles, conjugated linoleic acid, and ractopamine (paylean) on growth performance and fat characteristics of late finishing pigs.

An experiment was performed to evaluate effects of dietary ractopamine, CLA, and corn distillers dried grains with solubles (DDGS) on growth and carcass and fat quality of finishing pigs. This study was conducted as a split-split plot arrangement in a generalized randomized block design. In total 1,102 crossbred barrows and gilts (initial BW = 100.4 kg, SD = 3.7 kg; pic 337 × c22) were randomly assigned to 1 of 8 dietary treatments that consisted of 2 diet sources [corn-soybean meal (corn-soy) and corn-soy + 20% DDGS], 2 levels of ractopamine (0 and 7.4 mg/kg), and 2 levels of CLA (0% and 0.6%). The pen was the experimental unit, with 6 replications per treatment for a total of 48 pens with 23 pigs per pen. Pigs had ad libitum access to water and feed during the 27-d experimental period. Ractopamine addition improved (p < 0.05) ADG and G:F over the control group. Furthermore, carcass weight, carcass yield, loin depth, and lean percentage were increased and back fat depth was decreased (p < 0.05) by feeding ractopamine. Feeding CLA resulted in improved (p < 0.05) ADG and G:F and increased lean percentage but reduced carcass yield (p < 0.05). The inclusion of DDGS did not affect ADG, adfi, or g:f but reduced (p < 0.05) carcass dressing percent. An increase (p < 0.05) in the concentration of pufa was observed with inclusion of DDGS, ractopamine, and CLA. Iodine value (iv) increased (p < 0.001) in both belly and jowl samples by feeding DDGS and ractopamine, whereas a decrease (p < 0.01) was observed when CLA was included in the diets. The fatty acid profiles of belly and jowl fat samples were affected (p < 0.05) by diet source × ractopamine, indicating that effects of dietary ractopamine depend on the fatty acid profile of the diet. These results indicate that feeding ractopamine and CLA could improve growth and carcass measures and that CLA was effective in diminishing some of the negative effects, especially on IV, caused by DDGS.

The effect of corn distiller's dried grains with solubles, ractopamine, and conjugated linoleic acid on the carcass performance, meat quality, and shelf-life characteristics of fresh pork following three different storage methods.

The objective of this study was to evaluate dietary corn distiller's dried grains with solubles (DDGS), ractopamine hydrochloride (RAC), and conjugated linoleic acid (CLA) on growth performance, carcass and fat quality, and shelf-life of fresh pork from finishing pigs. Barrows (n=72) were fed one of eight treatments consisting of two diet sources (corn-soy and corn-soy+20% DDGS), two levels of RAC (0 and 7.4ppm), and two levels of CLA (0 and 0.6%) for 28days. Loins were portioned (n=3) into one of three storage conditions (fresh, cold, frozen); each followed with seven days of retail display. Feeding RAC improved ADG and G:F (P<0.05), whereas DDGS decreased belly fat firmness (P<0.05). Dietary DDGS increased total polyunsaturated fatty acids in jowl and belly samples and increased Iodine Value (IV) (P<0.05), but addition of CLA decreased IV. Dietary DDGS, RAC, or CLA had minimal impact on pork quality following varied storage methods.