EFFECT OF ORAL LOADING OF ACID OR BASE ON THE INCIDENCE OF PALE SOFT EXUDATIVE PORK (PSE) IN STRESS-SUSCEPTIBLE PIGS

Thirty-three halothane-positive pigs were assigned to one of three ad libitum water treatments 4 days prior to slaughter: control, sodium bi carbonate (12.6 g litre-1), or ammonium chloride (8 g litre-1) to stud y the effect of an oral acid or base load on post-mortem changes in th e longissimus dorsi muscle and on ultimate pork quality. Eight halotha ne-negative pigs were also slaughtered as negative controls. Dietary a mmonium chloride caused a metabolic acidosis as indicated by lower blo od and urine pH, and lower blood bicarbonate in treated pigs. In halot hane-positive pigs, dietary treatments had no significant effect on po st-mortem muscle pH changes or on measurements of muscle quality (colo ur, drip loss, texture scores or protein solubility). There was a weak to modest relationship between the blood gas measurements and meat qu ality indicators. Blood pH (r = 0.566) and bicarbonate (r = 0.514) wer e positively correlated with subjective texture scores and a trend was seen for blood PCO2 and bicarbonate to be positively related to 45 mi n pH and subjective colour. These observations suggest that pigs with increased blood pH and bicarbonate may show an improvement in meat qua lity. Further research is necessary to find the optimum time and level of treatment to maximize the response.