Management and nutritional approaches to reducing glycolytic potential and stress responses in pigs

High muscle glycolytic potential (GP) and blood acidosis induced by handling can result in losses of pigs during the pre-slaughter handling and in production of low quality pork. Studies were conducted to evaluate the effects of management and nutrition on muscle GP, blood responses to handling, and meat quality in pigs. Initially it was evaluated the effect of sampling location on variation in pork quality attributes and GP throughout longissimus muscle, and the effect of frequency and timing of biopsy sampling on muscle GP. These studies demonstrated that sample location affects (P < 0.05) pork quality traits and GP in longissimus muscle, but frequency and timing of biopsy sampling do not affect GP. One study investigated the effect of fasting and handling intensity on muscle GP and blood acid-base balance in pigs. This study indicated that fasting pigs for 24 hours did not attenuate the blood acidosis induced by handling, but the combination of fasting and handling reduced (P < 0.05) muscle GP. Another study was conducted to investigate the effects of dietary energy source (control vs. low carbohydrate vs. high fat vs. high fat-low carbohydrate) and fasting (0 vs. 36 h) on the dynamics of muscle GP and blood acid-base balance in response to handling. Dietary energy source and fasting did not affect blood acid-base responses to handling, but feed withdrawal and high dietary fat level reduced (P < 0.05) muscle GP. However, handling induced-depletion of muscle GP was higher (P < 0.05) in fasted than in fed pigs receiving control or high fat diets. When low carbohydrate diet with either low or high fat level was fed, GP depletion was similar in fasted and in fed pigs. The last study was carried out to evaluate the effect of dietary energy source on pork quality. Feeding high fat diets, either with or without low levels of digestible carbohydrates did not affect (P > 0.05) meat quality. The results from these studies indicate that feed withdrawal and dietary energy source do not reduce the acid-base responses induced by handling, but both approaches can be utilized to reduce muscle GP.