Effects of High Protein/low Carbohydrate Swine Diets During the Final Finishing Phase on Pork Muscle Quality

Pork color and water-holding capacity defects (pale, soft and exudative, or PSE pork) are functions of muscle pH and cost of the U.S. pork industry $60 million per year (Morgan et al., 1994). Pork with a low ultimate hP (pH\u3c5.5) has a paler color and lower water-holding capacity. Lactic acid build-up is responsible for lowering pH from 7.0, at the time of death, to 5.2-6.0 at 24h postmortem. Postmortem glycolysis produces lactic acid and can only occur in the presence of the substrate glycogen. Therefore, more glycogen in the muscle at slaughter will result in more lactic acid build up and a lower ultimate pH, which will result in a paler color and a lower water-holding capacity (Ellis et al, 1997) Consumption of carbohydrates is the main source of glucose in the blood (Guyton and Hall, 1996). In human studies conducted by Snitker et al., (1997) eight adult males were given one of two isoenergetic diets: a high-carbohydrate diet (75% of energy as carbohydrate, 15% as protein, and 10% as fat), or a low-carbohydrate diet (10% of energy as carbohydrate, 15% as protein, and 75% as fat) for three days. After the three day dietary maniuplation, glycogen content in the vastus lateralis muscle was significatnly lower for the low-carbohydrate subjects; 296 vs 426 mmol glucose/kg dry muscle, respectively (P\u3c0.001) (Snitker et al., 1997). Therefore, this study was conducted to determine if feeding ultra-high protein/low carbohydrate swine diets during the final finishing phase could reduce muscle glycogen and thereby imporve pork muscle quality