In the original article, some necessary information was omitted from Table 1.The label "ADFI, kg/d" should have been included in the first column to describe the third and fourth rows of data.The corrected table is shown below.

Ractopamine (RAC) is a feed ingredient for use in finishing pigs that increases pork carcass muscle protein and improves production efficiency. A mathematical analysis of the environmental effects of increased rate of gain, improved feed efficiency, and increased carcass leanness was conducted, and for the analysis, it was assumed that RAC was implemented in all finishing pig diets in the United States at 5 or 10 mg/kg of diet, while producing the same amount of pork protein that is currently being produced. The average responses to 5 or 10 mg/kg RAC fed for the last 28 d before market included a 5.3 or 5.9% increase in carcass protein percentage, a 0.31 or 0.81% increase in carcass yield, a 12.0 or 10.9% increase in ADG, a 0.5 or 2.5% reduction in ADFI, and a 9.3 or 14.3% improvement in G:F, respectively, and approximately 3 fewer days to market. Using these assumptions, the current amount of pork could be produced with 5.3 or 6.3% fewer pigs. Because of improved efficiency and the reduction in animal numbers, 2.8 or 3.4 billion fewer kilograms (equivalent to 0.29 or 0.35 million hectares) of corn and 0.16 or 0.34 billion fewer kilograms (equivalent to 0.059 or 0.127 million hectares) of soybeans would be needed for pork production each year, respectively. This reduction in cropland acreage would lead to an annual reduction of 79 or 97.4 million kilograms of fertilizer, 0.8 or 1.05 million kilograms of pesticides (herbicides and insecticides), and 184 or 233 billion liters of water, respectively. In conclusion, the implementation of RAC in swine diets results in a reduced natural resource demand for pork production and improved environmental stewardship.

The objective of this study was to investigate the effects of feeding diets with 10ppm of ractopamine hydrochloride (RAC; Paylean 9G, Elanco Animal Health, Greenfield, IN) to heavy-weight pigs (final BW of 147kg). Few studies have addressed the effects of RAC on performance and carcass traits at the finishing BW presented in this study. This study was carried out as a randomized complete block design with a 2×2 factorial arrangement of treatments, 1) sex (barrow or gilt) and 2) RAC inclusion (0 or 10ppm), with a total of 128 pigs. Pigs were randomly assigned to pens of 4 and beginning BW was approximately 115kg. After 28 d on test, pigs were slaughtered and a subset of pigs, totaling 64 pigs (2 pigs/pen), were selected for carcass characteristics and meat quality analysis. There were no sex×RAC interactions (P>0.10). Final farm BW was increased (P=0.003) by 3.3kg, overall ADG was increased (P=0.009) by 11.0%, and overall G:F was increased (P<0.001) by 12.9% with RAC. The HCW was increased (P<0.001) by 3.9kg with RAC, and dressing percentage was increased (P=0.001) to 76.04% from 75.06%. In the subset selected for carcass characteristics (n=64), there was a trend of increasing (P=0.08) lean cut yield. Ultimate pH was increased (P<0.001) by 0.08 units, and drip loss was decreased (P=0.011) to 4.31% from 5.59% with RAC. Feeding diets with 10ppm RAC to pigs with ending BW of approximately 147kg proved efficacious in improving BW, ADG, G:F, HCW, and dressing percentage without adversely affecting meat quality traits.

Crossbred pigs (n = 216) were used to test the interactive effect, if any, of ractopamine (RAC) and dietary fat source on the performance of finishing pigs, pork carcass characteristics, and quality of LM chops during 5 d of simulated retail display (2.6 degrees C and 1,600 lx warm-white fluorescent lighting). Pigs were blocked by BW and allotted randomly to pens (6 pigs/pen), and, after receiving a common diet devoid of RAC for 2 wk, pens within blocks were assigned randomly to 1 of 4 diets in a 2 x 2 factorial arrangement, with 5% fat [beef tallow (BT) vs. soybean oil (SBO)] and RAC (0 vs. 10 mg/kg). Diets were formulated to contain 3.1 g of lysine/Mcal of ME and 3.48 Mcal/kg of ME. Across the entire 35-d trial, pigs fed RAC had greater (P < 0.01) ADG and G:F, but RAC did not affect (P = 0.09) ADFI; however, performance was not affected (P >or= 0.07) by dietary fat source. Carcass weight, LM depth, and lean muscle yield were increased (P < 0.01), whereas fat depth was decreased (P = 0.01), in carcasses from RAC-fed pigs; however, carcass composition measures were similar (P >or= 0.27) between fat sources. Feeding 10 mg/kg of RAC reduced (P

Ractopamine HCl (RAC) is a phenethanolamine β-adrenergic agonist used as a feed supplement that repartitions nutrients from fat deposition to increased protein synthesis and muscle protein accretion without deleteriously affecting pork quality. This literature review, as well as meta-analyses of the available results, was undertaken to evaluate the live performance, carcass, and pork quality responses to the various dietary inclusion levels (0, 5, 10, and 20 mg/kg) of RAC. Consensus of literature and meta-analysis indicated that pigs fed RAC, regardless of dietary inclusion level, gained faster (P < 0.001) and more efficiently (P < 0.001) and produced heavier (P = 0.024), more muscular (P < 0.001) carcasses than pigs fed untreated control diets. Furthermore, carcasses from pigs fed diets containing 10 and 20 mg/kg (but not 5) of RAC were trimmer (P < 0.001) and had greater percentages of fat-free lean (P < 0.001) than carcasses of untreated controls. The literature indicates that dietary RAC has no deleterious effects on fresh pork color, firmness, and water-holding capacity; and, although some studies have noted a reduction in marbling, i.m. fat content, or both, meta-analysis of the available information reveals that RAC does not (P = 0.994) alter marbling or i.m. fat content. Inclusion of RAC in swine finishing diets will, therefore, effectively improve performance and carcass compositional attributes that are economically relevant to today's swine producers.

Crossbred pigs (n = 216) were used to test the interaction, if any, of ractopamine (RAC) and dietary fat source on the characteristics of fresh pork bellies. Pigs were blocked by BW (77.6 +/- 6.5 kg) and allotted randomly to pens (6 pigs/pen). After receiving a common diet devoid of RAC for 2 wk, pens within blocks were assigned randomly to 1 of 4 treatments arranged in a 2 x 2 factorial design, with 5% fat (beef tallow vs. soybean oil) and RAC (0 vs. 10 mg/kg). At the conclusion of the 35-d feeding period, pigs were slaughtered at a commercial pork packing plant (average BW of 108.8 +/- 0.6 kg), and fresh bellies were captured during carcass fabrication. Neither RAC (P = 0.362) nor fat source (P = 0.247) affected belly thickness. Subjective (bar-suspension) or objective (compression test) measures of belly firmness were not (P > or = 0.148) affected by the inclusion of RAC in the diet; however, bellies from pigs fed soybean oil (SBO) were softer than those from pigs fed beef tallow (BT), as indicated by perpendicular (P < or = 0.005) and parallel (P < 0.001) suspensions. Moreover, bellies from BT-fed pigs required more (P = 0.096) force to compress 50% of their thickness than bellies from SBO-fed pigs (52.29 vs. 43.51 kg). Color (L*, a*, and b* values) of the belly lean and fat was not (P > or = 0.131) affected by RAC, and lean color was similar (P > or = 0.262) between fat sources; however, belly fat from BT-fed pigs was lighter (P = 0.030) and redder (P = 0.013) in color than belly fat from SBO-fed pigs. Bellies of SBO-fed pigs had greater (P < 0.001) proportions of PUFA and lower (P < 0.001) proportions of SFA and MUFA than belly fat from pigs fed BT. Regardless of the RAC inclusion level, PUFA:SFA and iodine values were lower in belly fat from pigs fed BT than SBO; however, within SBO-fed pigs, PUFA:SFA and iodine values were further increased by feeding RAC (RAC x fat source, P < 0.001). As expected, dietary fat source altered the fatty acid composition of fresh pork bellies, which subsequently impacted fresh belly firmness. Interestingly, including RAC in swine finishing diets exacerbated the effect of feeding SBO on pork fat polyunsaturation.

from 10d to 15d (P<.01), indicating onset of lactation. Megalin expression increased about 3-fold from 0d to 5d (P=.01), then decreased 2.8-fold by 10d (P=.01). Gene expression of LDL-R decreased 4.5-fold (P<.06) from 5d to 10d while folic acid receptor mRNA decreased about twofold (P<.05). We conclude that temporal changes in expression of megalin, LDL-R and folic receptor mRNA during colostrogenesis may be related to the transport of their ligands into colostrum. Hormonal induction of lactation provided a useful model for studying the regulation of colostrogenesis.