The effect of ractopamine hydrochloride (paylean®) on lean carcass yields and pork quality characteristics of heavy pigs fed normal and amino acid fortified diets

The effect of ractopamine hydrochloride (PayleanÒ) on lean carcass yields and porkquality characteristics of heavy pigs fed normal and amino acid fortified diets S.N. Carr b, D.N. Hamilton c, K.D. Miller b, A.L. Schroeder b, D. Fernández-Dueñas a, J. Killefer a, M. Ellis a,F.K. McKeith a,* a University of Illinois at Urbana-Champaign, Department of Animal Sciences, 1503 S. Maryland Dr., 205 Meat Science Lab, Urbana IL 61801, United Statesb Elanco Animal Health, A Division of Eli Lilly and Company, 2001 West Main Street, Greenfield, IN 46140, United Statesc Génétiporc LLC, 606 3rd Avenue, W. Alexandria, MN 56308, United States Effects of ractopamine hydrochloride (RAC) on carcass parameters in heavy weight (133.24 ± 8.07 kg) fin- ishing pigs (n = 278) given amino acid fortified (AA) or 16% crude protein (CP) diets were evaluated. A Received in revised form 2 September 2008 total of seven experimental diets were formulated; RAC was added at 0, 5 and 20 ppm to the 16% CP diets (CP0, CP5 and CP20, respectively) and at 0, 5, 10 and 20 ppm to the AA fortified diets (AA0, AA5, AA10 andAA20, respectively). Carcass, tenderloin, and ham weights were heavier (P < 0.05) for RAC AA diets vs.
AA0. Loin weight was heavier (P < 0.05) for AA20 vs. AA0 and CP20 vs. CP0. No differences (P > 0.05) were observed for color or firmness scores. Carcass muscle score, ham weight and protein% were greater (P < 0.05) for RAC diets. Moisture was greater (P < 0.05) and fat was lower (P < 0.05) for AA5 and AA20 vs. AA0 and CP5 and CP20 vs. CP0. Feeding RAC to late finishing swine increases carcass yields and pro- tein% with lower fat% for pigs weighing up to 136 kg.
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from approximately 109 kg to an average market weight today ofapproximately 125 kg with some pigs reaching an average slaugh- Ractopamine hydrochloride (RAC) is a phenethanolamine with ter weight of 140 kg. As pigs become older and heavier, the addi- beta-adrenergic agonist properties and has been reported to in- tional weight gain is often accompanied by an increase in the crease leanness and reduce the amount of fat in pork carcasses amount of fat being deposited at different anatomic positions of as well as exhibit positive effects on growth performance traits in pigs. RAC effects on carcass composition and pork quality have be marketed at heavier weights (125 kg) while not deleteriously affecting growth efficiencies or carcass characteristics. Ractop- amine has been approved for use in finishing swine weighing from numerous production changes that have transpired in the United 68 to 109 kg in the United States since December of 1999 and was States over the last decade. Those changes include genetics and recently given approval by the Food Drug Administration (FDA) in management practices, such as selecting pigs to be much leaner; May of 2006 to be fed at levels ranging from 5 to 10 ppm to finish- producing a leaner meat product for consumers. A management ing swine for the last 20.4 to 40.8 kg of gain prior to harvest.
change in swine production is the use of lower crude protein diets The objective of this experiment was to characterize the effect supplemented with the addition of synthetic amino acids. This of different levels of RAC on carcass parameters in heavy weight strategy is intended to lower the amount of nitrogen excreted in finishing pigs (reared from approximately 99 kg to an approximate the feces and urine of the pig as the amount of nitrogen in the diet target final weight of 136 kg) fed amino acid (AA) fortified or 16% and the pig nitrogen requirements are more closely balanced ation is the weight at which pigs are marketed. Market weightshave gradually increased over the past decade in the United States 2.1. Experimental design, animals and diets One hundred thirty eight barrows and one hundred forty gilts * Corresponding author. Tel.: +1 217 333 1684; fax: +1 217 244 5142.
(PIC 337 sire  PIC C22 dams) were used for this experiment. The 0309-1740/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved.
doi:10.1016/j.meatsci.2008.10.007 S.N. Carr et al. / Meat Science 81 (2009) 533–539 study was carried out as a randomized complete block design. Pigs mately 133 and 139. These pigs were selected and slaughtered were reared during two time periods (replication in time) with an for collection of carcass data on an equal weight basis. At the end initial weight of approximately 99 ± 5.4 kg. Each rearing period of the equal time study, pens not corresponding to the weight pre- (replication in time) consisted of two blocks of barrows and two requisites for carcass evaluation were maintained on RAC treated blocks of gilts, totally four blocks of each gender. Blocks were ran- feed until weights concurred with the defined weight require- domly assigned to an environmental location within the finishing facility. Animals were penned in groups of five pigs during the Once the weight prerequisites were met, pigs were transported rearing period (five pigs/pen) for a total of 56 observations (eight to the University of Illinois, Meat Science Laboratory for slaughter the following morning. At the Meat Science Laboratory, the pigs The diets were formulated to meet or exceed were kept overnight in two pens with a similar number of pigs requirements for vitamins and minerals. The calculated nutrient for each treatment represented in each pen. Pigs were provided ac- content of the diets for this trial is presented in Major feed cess to water, but not access to feed. At approximately 0700 in the ingredients used in formulation of the diets were corn and soybean morning after delivery the pigs were harvested in a random order.
meal, along with appropriate commercial sources of vitamin and The pigs were weighed immediately prior to immobilization.
mineral premixes. Diets formulated to provide 16% CP were the After immobilization the pigs were exsanguinated, scalded, dehai- same for barrows and gilts. At the conclusion of the live phase, red, decapitated, eviscerated, split and placed immediately into a two or three pigs in each pen were designated for carcass dissec- 4 °C cooler. The approximate time from stun to cooler was 45 min.
tion based on final average weight. If less than two pigs weighed At approximately 24 h postmortem, the following carcass data within the weight window, approximately 133–139 kg, pigs imme- were collected: chilled whole carcass weight, chilled right side car- diately above and below the window were selected for dissection.
cass weight, chilled left side carcass weight, carcass length, and When more than two pigs weighed within the weight window, the carcass muscling score based on a subjective five point scale two pigs with the highest carcass priority ranking were selected.
Carcass priority ranking was randomly assigned to each pig within Backfat measurements were taken at the mid line and perpen- all pens prior to conclusion of live phase.
dicular to the skin, and included the skin. All linear fat measure- Amino acid diets were formulated to meet the requirements of ments, which included first rib, last rib and last lumbar vertebra each gender as well as lean growth potential of the animal. Esti- were taken and recorded for each carcass. The sides were ribbed mated lean growth rates were then increased 35% compared to by making a slice perpendicular to the backbone through the lon- control pigs (according to previous research) to reflect the ex- gissimus between the 10th and 11th ribs. Tenth rib backfat was pected increases in lean growth when 20 ppm RAC was added to measured at the 3=4 location over the longissimus muscle of the the diet. The AA fortified diets had lower levels of protein 10th rib of the thoracic vertebra. The longissimus muscle was al- ). Each diet was formulated from estimated lean gain potential lowed to ‘‘bloom” for approximately 5–15 min prior to evaluating and feed intake to contain the minimum CP content that would re- the muscle for quality variables. After evaluating the longissimus sult in an AA balanced ration for lysine, methionine, threonine, and muscle, a value was recorded for each of the meat quality vari- tryptophan. Amino acid fortified diets were very similar in AA con- ables: subjective color, marbling (and firmness tent considering lean growth potential and feed intake levels. A to- ). Longissimus muscle area was traced on acetate film for later tal of seven experimental diets were formulated (1) 16% CP diet with no addition of RAC (CP0); (2) as diet one, but RAC added at The right side of each carcass was fabricated for the determina- 5 ppm (CP5); (3) as diet one, but RAC added at 20 ppm (CP20); tion of fat-free lean percentage (data not presented) and proximate (4) AA fortified diets with no addition of RAC (AA0); (5) as diet four, analysis determination. Carcass side was separated into soft tis- but RAC added at 5 ppm (AA5); (6) as diet four, but RAC added at sues, bone plus connective tissue and skin. All three components 10 ppm (AA10) and (7) as diet four, but RAC added at 20 ppm were then weighed. Soft tissues were then ground at least two times. The grinding procedure was as follows: initial grind througha grinder plate (>12.7 mm). After grinding, the soft tissue was 2.2. Carcass, meat evaluation and proximate analysis mixed thoroughly and prepared for the second grinding, whichwas through a grinder plate (%12.7 mm). The ground soft tissue Carcass phase of the trial was designed as an equal weight was mixed and random samples were collected to form a compos- study. At the end of the equal time study period, individual pig ite sample weighing approximately 3.5–5.4 kg. The composite weight by pen averaged approximately 136 kg. Pens contained at samples were hand-mixed and prepared for the third homogeniza- least one and preferably two pigs averaging between approxi- tion, which was made with a bowl chopper (Talsa, model C40P,Spain). The chopping time was longer than 30 s on the highestspeed possible. These sub-samples where then bagged in Whirl-pakTM bags. Subsequently, proximate analysis was conducted for moisture, fat, protein and ash determination. Duplicate 5 g samples Calculated nutrient profile of the experimental diets.
were oven dried (105 °C, 24 h) to determine percent moisture. Per-cent fat was determined on the samples extracted with a 4:1 mix- ). Percent protein was determined using duplicate 3 g samples using the Kjeldahl method (). Percent ash was determined (using duplicate 5 g samples ig- nited (550 °C, 8 h) in a muffle furnace (Blue M Box Furnace, model The side of the carcass that was not used for determination of fat-free lean and proximate analysis was then further processed into wholesale cuts (trimmed) and boneless sub-primal and their respective weights captured. Trimmings were also collected and S.N. Carr et al. / Meat Science 81 (2009) 533–539 The PROC MIXED procedure of SAS was used to ana- lyze the data with the pig being used as the experimental unit for the carcass phase of the experiment. The model included the ef-fects of level of RAC, gender, and replication nested within block as a random effect and all interactions. Desired treatment compar- isons (AA0 vs. AA5; AA0 vs. AA10; AA0 vs. AA20; CP0 vs. CP5; CP0 vs. CP20; barrow vs. gilt) were tested for selected single degree offreedom contrasts.
Final weight, carcass weights, backfat, loin eye area, and carcass length measurements are presented in Average final weight was 133.24 ± 8.07 kg. Hot and cold carcass weights were greater (P < 0.05) with the addition of RAC in the AA fortified diets.
and also reported greater car-cass weights for pigs fed RAC when compared to control pigs. Car- cass weights did not differ (P > 0.05) among pigs fed the CP diets.
No differences were observed (P > 0.05) in carcass lengths from pigs in any of the CP diets. This is in agreement with the findings shorter (P < 0.05) than the AA0. For all backfat measurements, bar- rows exhibited a larger (P < 0.05) amount of backfat compared to (P < 0.05) were observed with CP20 treated pigs being leaner com- pared to the CP0 pigs for last lumbar and 10th rib. Tenth rib fatdepths were also lower (P < 0.05) for AA20 compared to the AA0.
(P > 0.05) in 10th rib backfat thickness. Pigs from their trials were slaughtered at live weight of approximately 104 and 109 kg, respectively compared to the targeted average ending live weight of approximately 136 kg from this study. With the remaining back- fat measurements, no differences (P > 0.05) were observed be- tween the controls and the RAC supplemented pigs. all reported similar decreases (P < 0.05) in 10th rib fat Loin eye area was increased (P < 0.05) in pigs fed AA10 and AA20 compared to AA0. Pigs fed the CP20 also yielded a larger (P < 0.05) loin eye area compared to CP0. These results are in agree- ment with the findings of and which observed increasing loin eye areas with increasing levels of RAC. For this experiment, the CP5 and AA5 diets were not different (P > 0.05) compared to their respective controls.
Subjective loin quality measurements are presented in .
Gender affected (P < 0.05) color and firmness scores with the barrows being darker and firmer. In contrast, in color scores. Pigs given RAC had greater (P < 0.05) muscle scores for all levels of AA fortified diets compared to AA0 and both levelsof CP diets compared to CP0. This is in agreement with , which also observed an increase in muscling score values Subjective color scores were not changed by the addition of RAC to either the AA fortified diets or the CP diets. This is in agreement topamine fed pigs also did not differ in firmness from the controls.
Again this is consistent with the findings from Subjective marbling scores were different (P < 0.05) between genders with barrows exhibiting greater marbling scores than gilts.
S.N. Carr et al. / Meat Science 81 (2009) 533–539 This was expected as barrows accrete fat at an earlier chronologicalage compared to gilts ( The CP diet supplemented with 20 ppm of RAC had a greater (P < 0.05) marbling score than CP0. These results are inconsistentwith those reported by ported no differences (P > 0.05). One possible explanation for thiscould be that contemporary animals fed a 16% CP diet with RAC supplementation are not meeting their amino acid requirementfor maximal lean accretion. With the addition of RAC to the diet, the lean growth potential of the animal is increased. observed that feeding pigs a lysinedeficient diet for five weeks prior to slaughter resulted in an in- crease in the intramuscular fat content of the longissimus at the10th rib. The marbling levels for this experiment were lower (P < 0.05) for the AA10 compared to AA0.
All trimmed wholesale and boneless weights represent the weights of the respective cuts from a single side of the carcass.
The number preceding the cut description is the Institutional MeatPurchase Specification () and North American Meat Pro- cessors Association ) number of the cut most closely associated with the actual cut specifications.
Trimmed wholesale cut weights are presented in The ham (401) collar off was heavier (P < 0.05) for AA5, AA10 and AA20 fed pigs compared to the AA0 diet. This cut was also heavier (P < 0.05) for the CP5 and CP20 diets compared to the CP0 fed pigs.
This increase in 401 ham weight is consistent to the findings of(RAC at 5, 10 and 20 ppm), ; (RAC at 20 ppm) and ; (RAC at 10 and20 ppm). No differences were observed between the AA0 and AA diets supplemented with RAC or the CP0 and CP diets supple- mented with RAC for the picnic (405) which was consistent with fed the AA5, AA20 and CP20 diets were heavier (P < 0.05) for theBoston butt (406) and loin (410) compared to the AA0 and CP0 con- trols, respectively, which was consistent with results reported by (P > 0.05) were observed between AA0 and AA10 as well as CP0 and CP5 for the Boston butt (406) and loin (410). The belly (409Bskin on) was heavier for the AA5 compared to AA0 which was inconsistent with results reported by where bel- ly was not different when animals were fed high RAC levels. No dif-ferences (P > 0.05) were observed between the RAC supplemented diets and their controls in either the CP or the AA fortified diets for side weight, or spareribs (416). These results were inconsistent to spareribs were heavier when animals were fed high RAC levels. In gender comparisons, gilts did have a heavier (P < 0.05) loin (410) Belly (409B) weight had a sex by RAC interaction (P < 0.05) for AA0 vs. AA10 and AA0 vs. AA20 as well as CP0 vs. CP5 with weight.
The addition of RAC increased belly (409B) weights more in bar- The boneless cut weights are presented in No differ- ences (P > 0.05) were observed between the RAC supplemented diets and the controls in either the AA fortified diets or the CP diets for the ham (402F), ham knuckle (402G), picnic (405A), and cush- ion (405B). The ham (402B), ham knuckle (402G), tenderloin and trimmings were all heavier (P < 0.05) for the AA diets supple- mented with RAC compared to the AA0 diet. The loin (414) was heavier (P < 0.05) for the CP20 fed pigs compared to the CP0, aswell as for the AA20 compared to the AA0 fed pigs. observed increased ham weight, knuckle, tenderloin and loin at high RAC levels (10 and 20 ppm). No differences (P > 0.05) were observed in the sirloin weight for the CP5 and CP20 fed pigs compared to the CP0, nor for AA10 compared to the AA0 fed pigs.
Table 4Effect of ractopamine hydrochloride (PayleanÒ) on trimmed wholesale cut weights of heavy pigs fed normal and amino acid fortified diets (kg) aAccording to the Institutional Meat Purchase Specification ( Effects of ractopamine hydrochloride (PayleanÒ) on boneless cut weights of heavy pigs fed normal and amino acid fortified diets (kg) aAccording to the Institutional Meat Purchase Specification ( S.N. Carr et al. / Meat Science 81 (2009) 533–539 The Boston butt (406A) was heavier (P < 0.05) for CP20 comparedto the CP0 fed pigs, and for AA20 and AA10 compared to the AA0 fed pigs. reported heavier (P < 0.05) Boston butt weights with increasing levels of RAC. Gilts exhibited heavier(P < 0.05) trimmings, tenderloin and loin (414) compared tobarrows.
Proximate analysis values of the whole side soft tissue of pigs are presented in . There was a gender difference (P < 0.05) for all treatments as the barrows yielded soft tissue that had morefat, less ash, less moisture and lower protein values compared to gilts. These results were consistent to those reported by and where moisture and protein were decreased whereas fat percentage was increased for barrows. In comparing treatments,no differences (P > 0.05) were observed in ash values for RAC sup- plemented diets compared to AA0. Pigs fed the CP5 and CP20 diets had greater (P < 0.05) ash values compared to CP0; this result wasconsistent with those ash values observed by when gilts were fed increased levels of dietarycrude protein and RAC. For fat and moisture values, RAC supple- mented diets yielded soft tissue samples that were lower (P < 0.05) in fat and greater (P < 0.05) in moisture compared to their controls with the exception of AA0 vs. AA10 which was only numerically greater for moisture and numerically lower for fat. All pigs supplemented with RAC in their diets had greater (P < 0.05) protein values compared to their respective control. Moisture, fat and protein results were consistent to those reported by Results from this study indicate that RAC has advantageous ef- fects on carcass characteristics and carcass cutting yields when fed to heavy weight swine using both CP and AA fortified dietary re- gimes. Pigs can be marketed at heavier weights (approximately136 kg) without affecting lean carcass characteristics that are de- sired by current market. Furthermore, results from this study con- firm previous research on lighter weight pigs that RAC increases carcass cut yields with decreased percentages of fat and increased percentages of protein for pigs weighing up to 136 kg. In conclu- sion, these results also indicated that RAC fed pigs can be marketed up to approximately 136 kg with no adverse effects on carcass lin-ear traits, carcass cutting yields or carcass quality.
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