Explore
Communities in English
Advertise on Engormix

Ractopamine (Paylean) Response in Heavy-Weight Finishing Pigs

Published: February 22, 2013
By: L. W. Kutzler, C. M. Peterson, Michael Ellis, F. K. McKeith, J. Killefer (Department of Animal Sciences, University of Illinois, Urbana 61801); S. N. Carr, M. J. Ritter, T. A. Armstrong, and PAS (Elanco Animal Health, Greenfield, IN 46140)
Summary

The objective of this study was to investigate the effects of feeding diets with 10 ppm of ractopamine hydrochloride (RAC; Paylean 9G, Elanco Animal Health, Greenfield, IN) to heavy-weight pigs (final BW of 147 kg). 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 10 ppm), with a total of 128 pigs. Pigs were randomly assigned to pens of 4 and beginning BW was approximately 115 kg. 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 3.3 kg, 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 3.9 kg 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 10 ppm RAC to pigs with ending BW of approximately 147 kg proved efficacious in improving BW, ADG, G:F, HCW, and dressing percentage without adversely affecting meat quality traits. 

Key words: cutting yield , finishing performance , pig. ractopamine

INTRODUCTION
Ractopamine hydrochloride (RAC) is an orally active β-adrenergic agonist that is incorporated into feed rations of finishing swine. Numerous studies have demonstrated the efficacy of RAC in improving ADG, feed efficiency, carcass weight, and dressing percentage, and its negligible effects on meat quality (Watkins et al., 1990; Stites et al., 1991; Uttaro et al., 1993; Crome et al., 1996; Carr et al., 2005b, 2009; Mimbs et al., 2005; Apple et al., 2007). Effective in April of 2006, the US Food and Drug Administration approved the feeding of 5 to 10 ppm RAC to finishing swine for the last 20.4 to 40.8 kg of BW gain. The previous label, valid from December of 1999 to April of 2006, approved the use of RAC in finishing swine weighing from 68 to 109 kg of BW. This new label opens the possibility of feeding RAC to swine at heavier final farm BW. Feeding swine to heavier final farm BW may offer economic benefits, such as increased kilograms of pork produced per sow per year as well as increased packer production efficiency (Crome et al., 1996). Few studies have addressed the efficacy of feeding RAC to swine with final farm BW of 130 to 140 kg. Crome et al. (1996) compared the growth and carcass response of finishing swine in 2 BW groups (107 and 125 kg final farm BW). They demonstrated that the heavier BW group still responded favorably to 10 and 20 ppm RAC in regard to growth performance and  carcass traits. In a component of a recent study by Carr et al. (2009), pigs were fed 5 and 20 ppm RAC with 16% CP to a final farm BW of approximately 133 kg. With pigs fed 20 ppm RAC, Carr et al. (2009)  demonstrated a 3.6 cm2 increase in loin eye area (LEA), a 0.35-unit increase in muscle score, and an increase of 0.46 kg on a ham trimmed wholesale cut [Institutional Meat Purchase Specification (IMPS)-401]. This study investigated the effects of 10 ppm RAC on finishing performance, carcass characteristics, and meat quality of pigs slaughtered at approximately 147 kg.
Ractopamine (Paylean) Response in Heavy-Weight Finishing Pigs - Image 1
MATERIALS AND METHODS
Experimental Design
The protocol for this study was approved by the Institutional Animal Care and Use Committee of the University of Illinois. The 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 10 ppm; Paylean 9G, Elanco Animal Health, Greenfield, IN). Pigs were the progeny of PIC 337 × C22 matings. The experiment was carried out over 4 blocks. Each block had 2 replicates, composed of 4 pens per replicate (1 per sex × RAC subclass), resulting in 32 pens across 4 blocks. Each pen housed 4 pigs, resulting in 128 pigs across 4 blocks. 
Allotment, Treatments, and Growth Performance Measurements
Pigs were allotted to pens to create average pen BW of approximately 107 kg. Once pigs were allotted, they were allowed to acclimate to their new pens for 7 d. During acclimation, pigs had ad libitum access to a control diet (Table 1). The 28-d test phase commenced at the end of the 7-d acclimation phase. While on test, pigs were given ad libitum access to the assigned diet (Table 1). Pigs were weighed weekly during the 28-d trial period to determine ADG. Feeder weights and feed additions to each feeder were recorded to determine ADFI (as-fed basis) and G:F. 
Carcass and Meat Quality Measurements
On the final day of test (d 28), pigs were weighed off test in the morning and were housed in their test pens with access to food and water until they were loaded and transported to either the University of Illinois Meat Science Laboratory or the commercial slaughter facility. The 2 pigs closest to the pen mean BW at d 28 were selected for carcass characteristics and meat quality analysis, and these pigs were transported to the University of Illinois Meat Science Laboratory on the morning of slaughter. Meanwhile, the remaining 2 pigs per pen were sent to a commercial slaughter facility on the morning of slaughter, where HCW and last-rib fat were collected for subsequent calculation of percentage of lean (National Pork Producers Council, 2001).
A subset of pigs, totaling 64 pigs (2 pigs/pen), were used to collect detailed measurements on carcass characteristics and fresh pork quality traits. Briefly, pigs were transported the morning of slaughter, electrically stunned, exsanguinated, scalded, dehaired, decapitated, eviscerated, split, inspected, and placed immediately into a 4°C chill cooler. Approximate time from stun to cooler was 45 min. Of the 2 pigs selected from each pen, one was randomly selected for pH decline and temperature decline measurements. Pigs that were selected for pH decline were measured at 45 min, 1.5 h, 3 h, 4.5 h, and 6 h with an MPI pH meter (Meat Probes Inc., Topeka, KS) in the LM of the right side of the carcass. The first time point was collected at approximately the 13th rib, and subsequent time points proceeded anteriorly by 1-rib increments. The temperature decline from 45 min to approximately 20 h was recorded with a temperature recorder (Monitor Company, Modesto, CA) inserted into the right side LM posterior to the last rib. 
After chilling for approximately 20 h, the left side was ribbed at the 10th rib and allowed to bloom for approximately 15 min. Last-rib and 10th-rib fat depths, and 10th-rib LEA were measured. Meat quality traits measured at the 10th rib included subjective color and marbling scores (National Pork Producers Council, 1999), subjective firmness (National Pork Producers Council, 1991), Japanese color score, and objective color using a Minolta CR-300 with a D65 light source and a 0° observer (Minolta Camera Company, Osaka, Japan). A section of LM was dissected out posterior to the 10th rib, and chops were cut. Chop collection beginning from the 10th rib included a 1.0-cm-thick chop, which was discarded; a 1.3-cmthick chop for drip loss; a 2.54-cmthick chop for proximate composition analysis; and a 2.54-cm-thick chop aged for 14 d for Warner-Bratzler shear force determination. Drip loss was used to evaluate water-holding capacity. Chops selected for drip loss measurement were weighed, suspended from a fishhook in a Whirl-Pak bag (NASCO, Fort Atkinson, WI) for approximately 24 h at 4°C, and then reweighed. Results were reported on a percentage loss basis. Proximate composition on homogenized samples was determined by oven drying to determine moisture content and by extraction with an azeotropic chloroformand- methanol mixture to determine extractable lipid, as described by Novakofski et al. (1989).
Ractopamine (Paylean) Response in Heavy-Weight Finishing Pigs - Image 2
The right side of each carcass was further processed to primals and boneless subprimals. Weights of primals, boneless subprimals, and intermediate cuts were collected. All weights represent the weights of the respective cuts from a single side of the carcass. The number associated with the cut description shown in tables is the IMPS (USDA, 1996) or the North American Meat Processors Association (1997) number most closely associated with actual cut specifications. Primal, subprimal, and boneless yields are expressed as a percentage of HCW and were calculated using the following equation: % of HCW =  [(2 × actual cut weight)/HCW] × 100. Lean cut yields were calculated by using the following formula: {[(boneless ham (inside + outside + knuckle + light butt) + Canadian back + boneless tenderloin + boneless sirloin + boneless Boston butt + boneless picnic] × 2}/HCW. The carcass cut yield is the lean cut yield plus the trimmed belly. The lean and fat trimmings generated from boneless cut fabrication were collected and ground, and proximate composition of moisture and extractable lipid was determined as described previously. 
Statistical Analysis 
Data were analyzed using the MIXED procedure (SAS Institute, 2000). The model included the effects of block, sex, RAC inclusion, and the sex × RAC inclusion interaction. The random effect of replicate within block was also included in the model for live animal performance. Pen was used as the experimental unit for the analysis of live performance, and pig was the experimental unit used in the carcass trial. No sex × RAC interactions for any of the criteria were measured; thus, only the main effects of RAC are discussed.
Ractopamine (Paylean) Response in Heavy-Weight Finishing Pigs - Image 3
Ractopamine (Paylean) Response in Heavy-Weight Finishing Pigs - Image 4
RESULTS AND DISCUSSION
Finishing Performance
Finishing performance is presented in Table 2. Live animal performance data are separated into 5 time periods: overall and wk 1, 2, 3, and 4. During wk 1 of the RAC feeding period, there was a trend for an increase (P = 0.08) in ADG, but there were no differences in BW, ADFI, or G:F. During wk 2, RAC increased (P < 0.01) BW, ADG, and G:F. The same response continued during wk 3, with an additional response of decreased (P = 0.03) ADFI. During wk 4, however, the only difference between treatments was BW (P = 0.003). Final farm BW was increased (P = 0.003) by 3.3 kg in the RAC treatment. Inclusion of RAC increased (P = 0.009) overall ADG by 11.0%, corresponding to an overall increase (P < 0.001) in G:F of 12.9%. These overall results are similar to results seen in pigs of lighter BW (Stites et al., 1991; Armstrong et al., 2004). 
Carcass Traits
Carcass traits are presented in Table 3 for all 128 pigs. The HCW was increased (P < 0.001) by 3.9 kg with RAC, and dressing percentage was increased (P = 0.001) to 76.04%, from 75.06%. Similar improvements in HCW and dressing percentage were seen in pigs approaching a similar final BW as targeted in this study (Crome et al., 1996). Watkins et al. (1990) and Carr et al. (2005b) also saw improvement in dressing percentage with 10 ppm RAC. Last-rib fat depth however, was not affected, which is similar to the results of Carr et al. (2005b). The combination of a heavier HCW and equal last-rib fat depth resulted in a greater amount (P < 0.001) of calculated fat-free lean. Effects of RAC on BW and carcass traits in the selected subset (2 pigs/ pen closest to the pen BW mean) are presented in Table 4. Final farm BW was increased (P = 0.007) by 4.1 kg and HCW was increased (P = 0.001) by 4.3 kg with RAC. Dressing percentage was increased (P = 0.02) to 76.13% from 75.34%. Tenth-rib and last-rib fat depths were unaffected by RAC (Table 4). Previous reports of 10 ppm RAC not affecting 10th-rib backfat have been reported (Stites et al., 1991; Armstrong et al., 2004). Inclusion of RAC also increased (P = 0.004) LEA by 3.19 cm2.
Ractopamine (Paylean) Response in Heavy-Weight Finishing Pigs - Image 5
Ractopamine (Paylean) Response in Heavy-Weight Finishing Pigs - Image 6
Carcass Cutting Yields
Effects of RAC on wholesale cut weights as a percentage of HCW are presented in Table 5. Fresh ham (IMPS-401) percentage (P = 0.03) was increased to 24.37% from 23.89% with RAC. This is similar to the results of Carr et al. (2005a), which showed similar increases in fresh ham (IMPS-401) weight percentage, but with 20 ppm RAC. Neck bone (IMPS-421) percentage, however, was decreased (P = 0.006) with RAC. Assuming equal skeletal weights, a decrease in neck bone percentage with the RAC treatment could be due to the resulting increase in HCW with RAC. Shoulder (IMPS-403), jowl, belly (IMPS-408), skin-on loin (IMPS 410), and sparerib (IMPS-416) percentages were unaffected (P > 0.16) by RAC.
Effects of RAC on trimmed wholesale weights as a percentage of HCW are presented in Table 6. Fresh ham (IMPS-401C), picnic (IMPS-405), Boston butt (IMPS-406), skin-on belly (IMPS-409B), and loin (IMPS- 410) percentages were not affected (P > 0.51) by RAC. However, when feeding 20 ppm, as in the study by Uttaro et al. (1993), and holding HCW equal, increases in trimmed weights of loin, ham, and belly were observed. Effects of RAC on boneless cut weights as a percentage of HCW are presented in Table 7. Fresh ham outside (IMPS-402E) percentage was increased (P = 0.003) to 5.18% from 4.93%, and tenderloin (IMPS-415A) percentage showed a trend (P = 0.09) toward an increase. Fresh ham inside (IMPS-402F), light butt, knuckle, picnic (IMPS-405A), Boston (IMPS- 406A), cellar trimmed butt (IMPS-407), Canadian back (IMPS-414), and sirloin percentages were not affected (P > 0.122) by RAC. Carr et al. (2005a), however, reported increases in Boston (IMPS-406A), Canadian back (IMPS-414), and sirloin weight percentages. The effect of RAC on trim composition is presented in Table 8. Lean cut yield values showed a trend toward an increase (P = 0.08) to 37.32% from 36.71%, whereas carcass cut yield was unaffected (P = 0.132; Table 8). The weight percentage of trimmings (IMPS-418) was unaffected by RAC; however, the percentage of moisture was increased (P = 0.05) and the percentage of extractable lipid was decreased (P = 0.01) 23.32% from 24.86% with RAC, resulting in an increase (P = 0.01) in the calculated trimmings fat-free lean percentage to 76.68%. These results coincide with those of Carr et al. (2005a).
Ractopamine (Paylean) Response in Heavy-Weight Finishing Pigs - Image 7
Ractopamine (Paylean) Response in Heavy-Weight Finishing Pigs - Image 8
Ractopamine (Paylean) Response in Heavy-Weight Finishing Pigs - Image 9
Meat Quality
Effects of RAC on meat quality were mixed, as presented in Table 9. National Pork Producers Council (1999) and Japanese color scores and National Pork Producers Council (1999) marbling scores were unaffected by RAC, as seen with other studies (Armstrong et al., 2004; Carr et al., 2005a). National Pork Producers Council (1991) firmness scores, however, were increased (P = 0.004) by 0.54 units with RAC. Objective color was affected by RAC treatment. The L* values showed a trend toward a decrease (P = 0.06; less white) of 1.91 units, the a* values were decreased (P < 0.0001; less red) by 1.73 units, and the b* values were decreased (P = 0.001; less yellow) by 1.36 units. The same trend with a* and b* was seen previously with 10 ppm (Carr et al., 2005a) and 20 ppm RAC (Uttaro et al., 1993). Ultimate  pH was increased (P < 0.0001) by 0.08 units, and drip loss was decreased (P = 0.01) to 4.31% from 5.59% with RAC. The temperature decline from 45 min to 20 h, and the pH decline from 45 min to 6 h were not different at any time point (data not presented), in agreement with the results of Carr et al. (2005b). Other meat quality traits, such as cook loss, shear force, loin percentage moisture, and loin extractable lipid, were also not affected. 
IMPLICATIONS
Feeding 10 ppm RAC to pigs with an ending BW of approximately 147 kg is efficacious in improving BW, ADG, G:F, carcass weight, dressing percentage, and calculated kilograms of fat-free lean. Dietary inclusion of 10 ppm RAC also has minimal effects on meat quality.
LITERATURE CITED
Apple, J. K., P. J. Rincker, F. K. McKeith, S. N. Carr, T. A. Armstrong, and P. D. Matzat. 2007. Review: Meta-analysis of the ractopamine response in finishing swine. Prof. Anim. Sci. 23:179.
Armstrong, T. A., D. J. Ivers, J. R. Wagner, D. B. Anderson, W. C. Weldon, and E. P. Berg. 2004. The effect of dietary ractopamine concentration and duration of feeding on growth performance, carcass characteristics, and meat quality of finishing pigs. J. Anim. Sci. 82:3245.
Carr, S. N., D. N. Hamilton, K. D. Miller, A. L. Schroeder, D. Fernández-Dueñas, J. Killefer, M. Ellis, and F. K. McKeith. 2009. The effect of ractopamine hydrochloride (Paylean ®) on lean carcass yields and pork  quality characteristics of heavy pigs fed normal and amino acid fortified diets. Meat Sci. 81:533. 
Carr, S. N., D. J. Ivers, D. B. Anderson, D. J. Jones, D. H. Mowrey, M. B. England, J. Killefer, P. J. Rincker, and F. K. McKeith. 2005a. The effects of ractopamine hydrochloride on lean carcass yields and pork quality characteristics. J. Anim. Sci. 83:2886. 
Carr, S. N., P. J. Rincker, J. Killefer, D. H. Baker, M. Ellis, and F. K. McKeith. 2005b. Effects of different cereal grains and ractopamine hydrochloride on performance, carcass characteristics, and fat quality in late-finishing pigs. J. Anim. Sci. 83:223. 
Crome, P. K., F. K. McKeith, T. R. Carr, D. J. Jones, D. H. Mowrey, and J. E. Cannon. 1996. Effect of ractopamine on growth performance, carcass composition, and cutting yields of pigs slaughtered at 107 and 125 kilograms. J. Anim. Sci. 74:709. 
Mimbs, K. J., T. D. Pringle, M. J. Azain, S. A. Meers, and T. A. Armstrong. 2005. Effects of ractopamine on performance and composition of pigs phenotypically sorted into fat and lean groups. J. Anim. Sci. 83:1361. 
National Pork Producers Council. 1991. Procedures to Evaluate Market Hogs. 3rd ed. Natl. Pork Prod. Counc., Des Moines, IA. 
National Pork Producers Council. 1999. Pork Quality Standards. Natl. Pork Prod. Counc., Des Moines, IA. 
National Pork Producers Council. 2001. Procedures for Estimating Pork Carcass Composition. Natl. Pork Prod. Counc., Des Moines, IA. 
North American Meat Processors  association. 1997. Meat Buyers Guide.North Am. Meat Processors Assoc., Reston, VA. Novakofski, J., S. Park, P. J. Bechtel, and F. K. McKeith. 1989. Composition of cooked pork chops: Effect of removing subcutaneous fat before cooking. J. Food Sci. 54:15.
SAS Institute. 2000. SAS User’s Guide. Version 8.1 Edition. SAS Inst. Inc., Cary, NC. Stites, C. R., F. K. McKeith, S. D. Singh, P. J. Bechtel, D. H. Mowrey, and D. J. Jones. 1991. The effect of ractopamine hydrochloride on the carcass cutting yields of finishing swine. J. Anim. Sci. 69:3094.
USDA. 1996. Institutional Meat Purchase Specifications. USDA Marketing and Regulatory Programs, Agricultural Marketing Service, Livestock and Seed Program, Washington, DC.
Uttaro, B. E., R. O. Ball, P. Dick, W. Rae, G. Vessie, and L. E. Jeremiah. 1993. Effect of ractopamine and sex on growth, carcass characteristics, processing yield, and meat quality characteristics of crossbred swine. J. Anim. Sci. 71:2439. 
Watkins, L. E., D. J. Jones, D. H. Mowrey, D. B. Anderson, and E. L. Veenhuizen. 1990. The effect of various levels of ractopamine hydrochloride on the performance and carcass characteristics of finishing swine. J. Anim. Sci. 68:3588.
Related topics
Authors:
Michael Ellis
University of Illinois
Follow
J. Killefer
University of Illinois
Follow
Join to be able to comment.
Once you join Engormix, you will be able to participate in all content and forums.
* Required information
Would you like to discuss another topic? Create a new post to engage with experts in the community.
Create a post
Join Engormix and be part of the largest agribusiness social network in the world.
LoginRegister