INTRODUCTION
Paylean® is a feed additive that was recently registered in Canada. The active ingredient of Paylean® is ractopamine, a beta-adrenergic agonist known to stimulate muscle growth and inhibit lipid growth. There is limited information available on the impact of RAC on the eating quality of pork and the results available are equivocal. Moreover, few studies used taste panel evaluation. Those studies that did evaluate meat quality suggested that RAC had no effect on visual colour, firmness, marbling or sensory juiciness and flavour properties. However, the effect of RAC was inconsistent for some quality traits, specifically, meat tenderness or Warner-Bratzler shear force. The acceptance of pork by the consumer is critical to the industry’s success, therefore it is important to determine if RAC has an impact on eating quality. The data reported here was from a larger trial (see part 1). The specific objective of part 2 was to evaluate the impact of feeding 5 ppm RAC on meat quality and the sensory characteristics of pork.

MATERIALS AND METHODS
The experiment was designed so that the average starting weight within a treatment would be 87 kg. This was to provide an average of 28 days on Paylean prior to slaughter.
All animals were fed a diet comparable to the barn’s normal gilt finisher, The experiment consisted of two treatments: control or 0.25% Paylean®, equivalent to 5 ppm ractopamine (RAC).

In each of two weeks, a total of 8 animals from each gender and treatment (32 animals per week) selected for shipping, were randomly selected for detailed meat quality analysis. Loin eye area and backfat measurements were determined following chilling. Loins were harvested one day post-slaughter, and cut into one inch chops for measurement of drip loss, subjective colour scores, chemical composition, sensory evaluation and shear force. Sensory analysis was conducted using 11 trained panellists. They were provided individual cubes of meat cooked to an internal temperature of 70 C.

RESULTS and DISCUSSION
Similar to the results shown by those feeding ractopamine at 10 ppm or 20 ppm, including ractopamine in the diet at 5 ppm did not markedly affect meat quality parameters (Table 1). pH, drip loss, and visual colour scores were unaffected (P > 0.05). Changes in some of the colour scores were statistically significant, however, the absolute differences are of uncertain significance from a consumer perspective.

Our observation that RAC had no effect on marbling is consistent with some published reports, but not others. The lack of an effect in our study may be due to our low inclusion rate. The decrease in back fat, and improvement in loin-eye area are consistent with the known nmechanism of action of ractopamine.

The increase in shear force, and decreases in observed tenderness supports previous reports that RAC may produce less tender pork. The effect of RAC on shear force was more pronounced in gilts, than barrows. Overall acceptability however, was not affected by the inclusion of RAC in the diet at 5 ppm (Table 2).

ACKNOWLEDGEMENTS
Strategic funding provided by Sask Pork, Alberta Pork, Manitoba Pork Council and Saskatchewan Agriculture and Food Development Fund. Specific funding for this project from Elanco Animal Health is gratefully acknowledged.