R. S. Emnett, S. J. Moeller1, K. M. Irvin, and D. L. Meeker
The Ohio State University Department of Animal Sciences
Improvement of meat quality is one of the primary concerns of the pork industry. Many genetic and environmental factors contribute to the quality of fresh and processed meat products. The dominant Rendement Napole gene (RN) has been found to have both positive and negative effects on pork quality. Currently, the best method for classification of animals as RN positive (RN-RN-, RN-rn+) or RN negative (rn+rn+) is the glycolytic potential test (GP). High-glycolytic potential indicates that the animal is a carrier of the RN gene.
This study investigates the effect of GP on pork-quality traits for a population of 576 post-mortem longissimus dorsi samples from the 1998 National Barrow Show Progeny Test. Animals were classified as high-glycolytic potential (n=26), or low-glycolytic potential (n=550), based on a GP threshold of 160 moles lactate equivalents per gram for the population bimodal distribution. Objective muscle-quality traits measured included loin pH (pH), water-holding capacity (WHC) measured as the weight (mg) of exudate absorbed on a filter paper, Instron tenderness (INS), percent cooking loss (CL), and Minolta color (MIN). Sensory scores evaluated included tenderness (TEN) and juiciness (JUC).
Residual correlations between GP and pH, INS, WHC, CL, and MIN were -0.55, 0.15, 0.20, 0.29, and 0.29, respectively. High GP pigs had significantly (P < 0.01) lower pH (5.42 vs. 5.57) and WHC (0.055 vs. 0.037), greater CL (22.0 vs. 19.2), and paler MIN color (25.24 vs. 23.02) than low GP pigs. No statistical differences were found between low- and high-GP pigs for INS, JUC, or TEN.
Breed was a significant source of variation for all traits evaluated. Berkshire and Chester White breeds exhibited significantly (P < 0.001) lower GP values than Hampshire or Hampshire-crossbred samples. The results of this study agree with previous research, indicating that high GP values are associated with lower pH, poorer WHC, higher CL, and paler color. The differences in GP across breeds warrant future studies to determine the relationship of GP to muscle quality and sensory traits.
1 For more information, contact at: The Ohio State University, Animal Science Building, 2029 Fyffe Road, Columbus, OH 43210, 614-488-3686, fax 614-292-2929, e-mail: moeller.29@osu.edu