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Virginia Cooperative Extension - Knowledge for the CommonWealth

Paylean Pork on the Hoof and the Fork
A Virginia Tech Youth Weekend Demonstration

Livestock Update, May 2001

J. Getz, L. Martin, D. Poyser, and C. M. Wood , Animal & Poultry Sciences

The feed additive Paylean® has been in the spotlight recently, with strong claims to improve finishing hog performance. Controlled research studies and anecdotal reports indicate that Paylean® can make finishing pigs more efficient, leaner, and heavier muscled, thereby improving the bottom line or standings in a show.

Paylean® is the commercial name for a compound called Ractopamine Hydrochloride. Ractopamine is a member of a family of compounds that have beta-adrenergic agonist activity. In general, beta agonists stimulate beta-receptors, which are responsible for a variety of functions throughout the sympathetic nervous system. Ractopamine appears to work by stimulating the beta-receptors to increase nitrogen retention, which increases muscle mass. Less energy is available for deposition as adipose tissue, resulting in improved leanness as well.

The most important thing to remember when using Paylean® is to follow the label directions. Animals should only be fed Paylean® during the last 90 lb of gain or the last 21 to 28 days before slaughter. If you feed the additive for more than the directed amount of time or at a higher than recommended rate the Paylean® will actually have an opposite effect and the animal will start to put on more fat because the beta receptors become saturated and stop responding.

Materials and Methods

To help illustrate these principles and give people a chance to see the results of feeding Paylean® in a controlled situation, four pens of four pigs each were used for a demonstration as part of the 2000 Youth Weekend held at Virginia Tech last December. The six gilts and 10 barrows ranged in initial weight from 141 to 194 lb so they were divided into two sets of heavyweight pigs and two sets of lightweight pigs. One pen in each set was fed a 16% CP control diet (Table 1) and the other set was fed the control diet supplemented with 18 g/ton of Paylean®. The four pens of pigs were fed for 27 days at the Virginia Tech Swine Center. The feed was weighed every day before it was added to the feeders and individual pigs were weighed weekly. At the end of the feeding period all pigs were weighed and ultrasonically scanned for backfat (BF) and loin depth (LD). Because of the small numbers of animals, a statistical analysis of the data was not possible, so the information presented applies only to these 16 animals.

For the live demonstration eight pigs (four control and four treated) chosen to illustrate the variable results of feeding Paylean® were brought to the Judging Pavilion for youth weekend participants to observe and evaluate for leanness, muscling, and structural soundness. Four of those pigs (two treated and two control) were slaughtered at the Virginia Tech Meats Lab that night and the carcasses were used in a seminar on Saturday. Two other pigs were slaughtered earlier in the week so a taste test could be conducted to determine if there were any effects on tenderness, juiciness, or flavor due to the Paylean® additive.

Table 1. Composition of the Control Diet Used in the Virginia Tech Paylean® Youth Weekend Demonstration
Ingredients lb/ton %
Ground Corn 1486.474.32
Soybean Meal, 44% CP 464.0 23.20
Dicalcium Phosphate 16.6 0.83
Ground Limestone17.4 0.87
Vitamin - Se Premix 5.0 0.25
Trace Mineral Premix 1.0 0.05
Salt 5.0 0.25
Copper Sulfate1.6 0.08
Tylosin (10/lb) 3.0 0.15
Totals 2000.0 100.0

Results and Discussion

Average daily gain (ADG) was positively affected by the addition of Paylean® to the diet (Table 2). The heavyweight Paylean® (HP) pigs and the lightweight Paylean® (LP) pigs showed a marked improvement in ADG compared to their respective controls. This result agrees with a summary of 20 studies (Weldon, 2000). As shown by the data in Table 2, however, the HP pigs did not respond to the Paylean® as well as the LP pigs in this demonstration. This difference may have been due to the HP pigs' beta receptor sites becoming desensitized (Herr et al., 2001). According to Schinckel (2000), the response to Paylean® can be variable and can peak well before the end of a 28-day period.

Table 2. Results of Feeding Paylean® for 27 Days to Heavyweight and Lightweight Pigs: Live Performance and Ultrasound Results
Pen ADG F/G Ratio Backfat Loin Depth % Lean
HP 2.38 3.20 1.06 2.47 50.62
HC 2.21 3.87 0.95 2.26 50.67
LP 2.46 3.32 0.87 2.13 51.18
LC 1.92 4.18 1.02 1.95 48.76
HP = Heavyweight Paylean; HC = Heavyweight Control; LP = Lightweight Paylean; LC = Lightweight Control
ADG = Average Daily Gain; F/G = Feed to Gain

In feed to gain ratio (F/G), the HP pigs and the LP pigs showed noticeable enhancement in efficiency compared to controls. This was expected because other studies have shown a 13% improvement in F/G when pigs were fed Paylean® (Harper, 2001). As with ADG, HP pigs apparently did not respond as well to the Paylean® as the LP pigs.

The results that were found for estimated backfat (BF) and percent lean (LEAN) were much more variable than for ADG and F/G (Table 2). Although LP pigs responded as expected to the Paylean®, with decreased backfat compared to controls (Chrome et al., 1996), BF of HP pigs was actually higher on average than the HC pigs. This result was due primarily to one HP pig that scanned 1.65 in BF. With only 16 pigs, one such pig certainly had an impact on the results.

When looking at the data for loin depth (LD), both of the Paylean® groups excelled when compared to the control groups, which is one reason LEAN was almost exactly the same for HP and HC pigs. In general, these results indicated that the Paylean® did increase muscling as the pigs grew, which agrees with other studies that had as much as a 14% increase in LD (Harper, 2001).

There have been some suggestions of soundness problems in pigs fed Paylean®. In this demonstration, some of the pigs were marginal in soundness at the start of the trial, but there was no appreciable deterioration of soundness either in control or in treated pigs. It was easy to see, however, that the extreme muscling in some of the pigs could have been a problem if they got much heavier. Also, it is important that adequate levels of dietary Ca and P be provided to pigs fed Paylean®. The diet used in this demonstration met or exceeded NRC recommendations for these two minerals. For show animals, care should be taken to choose pigs that are structurally sound to start with to avoid such problems.

Carcass data from the four pigs killed Friday night are shown in Table 3, and are similar to the ultrasound data obtained on the live pigs. As mentioned above, Pig No.1, which was an HP pig, had 1.65 in BF and was expected to be leaner and have a larger loin muscle area than it did. Pig No. 4, the other HP pig, was evaluated live as being extremely heavy muscled and in fact did have a 9.0 in2 loin muscle area. In addition, it measured 0.65 in BF at the 10th rib, but measured 1.40 in at the last rib. This fat deposition pattern is often seen in heavily muscled pigs, but the extreme amount of fat at the last rib was unexpected.

Results of the taste panel are presented in Table 4. The taste panel was set up as a blind test (none of the samples were identified in any way), and reflected the perceptions of the youth weekend participants, who were given no training before participating in this exercise. The boneless loins were cooked in the same oven for the same amount of time with the same preparation. Results indicate that there was not much difference between the control and Paylean® loins although there was a tendency for Paylean® pork to be less tender than control pork.

Table 4. Comparison of Cooked, Boneless Loins from Control and Paylean Pigs: Taste Panel Results
Taste Panel Characteristic Control Paylean
Tender 51 44
Not Tender 8 16
Juicy 31 29
Not Juicy28 32
Flavorful46 42
Not Flavorful 14 17
Characteristics were scored on a scale of 1 = Poor to 4 = Very Good. For purposes of the table, scores of 1 and 2 were combined as were scores of 3 and 4. Numbers in the table are the number of participants who recorded that score.

Table 3. Results of Feeding Paylean for 27 Days to Heavyweight and Lightweight Pigs: Carcass Data, USDA Grade, and Carcass Value
Pig
No.		 Live
Wt.		 Hot
Carcass Wt		 Dress
%		 10th
Rib BF		 Last
Rib BF		 Loin
Eye Area		 Length Muscle
Score		 %
Lean		 Marb
Score		 Col
Score		 Firm
Score		 USDA
Grade		 Carcass
Value
1(P) 268 199 74.3 1.65 1.70 6.05 31.60 2 43.3 3 3 4 4 $71.28
2(C) 266 198 74.4 0.90 1.20 7.05 33.20 2 52.8 2 3 2 2 $102.68
3(C) 254 192 75.6 0.80 1.15 6.75 32.70 2 53.3 2 3 3 2 $101.61
4(P) 247 194 78.5 0.65 1.40 9.00 32.20 3 59.3 1 2 3 2 $106.20
P - Paylean
C - Control
Marb = Marbling; Col = Color; Firm = Firmness

Another question often asked about Paylean® is whether it is cost effective to use. For this demonstration, carcass value was calculated based on the Smithfield buying system and cost of gain was calculated for each pen. A base carcass price of $50.45/cwt was used and adjustments for weight, BF, and LD were made for each animal. Using the diet specified in Table 1, the cost of Paylean® adds $0.0266 to a pound of feed, making the total cost per pound $0.1068 for the Paylean® feed and $0.0802 for the control feed. Despite the improved gain and feed efficiency exhibited by the Paylean® pigs in this demonstration, carcass premiums were not sufficient to offset the cost of using the additive. As a result, we lost $0.06/lb when feeding Paylean®. However, when considering the potential results of winning a show or improving your placing in a contest, the $0.06/lb loss might be a worthwhile investment

Table 5. Results of Feeding Paylean for 27 Days to Heavyweight and Lightweight Pigs: Percent Lean, Carcass Value, and Cost of Gain
Pen Percent Lean Carcass Value Cost of Gain
HP 50.62 $383.57 $0.34/lb
HC 50.67 $415.07 $0.31/lb
LP 51.18 $370.66 $0.35/lb
LC 48.76 $327.28 $0.34/lb
HP = Heavyweight Paylean; HC = Heavyweight Control; LP = Lightweight Paylean; LC = Lightweight Control

Literature Cited

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. 74:709­716.

Harper, A. F. 2001. PayleanTM (ractopamine) and 4H - FFA youth swine projects. In: January 2001 Livestock Update. VA Coop. Ext., Blacksburg.

Herr, C. T., A. P. Schinckel, L. Watkins, B. Weldon, and B. T. Richert. 2000. Optimal Paylean Sequence (Step-up/Step-down) When Fed to Late-Finishing Swine. www.ansc.purdue.edu/swine/poŠnutrient/paylean/OptimalPayleanSequence.html accessed March 30, 2001.

Schinckel, A. P., and B.T. Richert. 2000. Impact and Use of Paylean in Market Pigs. www.ansc.purdue.edu/swine/poŠnutrient/paylean/ImpactPaylean.html accessed March 30, 2001.

Weldon, W. C. 2000. Nutritional implications of ractopamine in finishing swine diets. In: Proceedings of the Carolina Nutrition Conference. North Carolina State Univ., Raleigh.



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