The effect of cyclopiazonic acid on the development of pale, soft, and exudative pork from pigs of defined malignant hyperthermia genotype

Malignant hyperthermia (MH) and the mycotoxin cyclopiazonic acid (CPA) are each associated with abnormal calcium homeostasis in skeletal muscle, a key underlying factor in the development of pale, soft, and exudative (PSE) po rk. To determine whether the natural presence of CPA in livestock feed ingr edients contributes to the varying incidence of PSE in the pork industry, v arious levels of CPA (.1 to 50 mg/kg of diet) were included in the diets of market weight hogs (n = 52) of defined malignant hyperthermia genotype ( N N = normal, Nn = a MH carrier, and nn = MH-positive). Animals with two copi es of the MH mutation (nn) displayed improved live animal performance compa red with NN and Nn animals (increased feed intake, average daily gain, and feed efficiency) but yielded lower quality loin chops as indicated by lower 45-min pH(P <.01), higher Commission Internationale de l'Eclairage (CIE) L * color coordinate values (P <.05), and higher drip losses (P <.01). The ef fects of CPA varied. In the first feeding trial, conducted under normal out side temperatures (2 degrees C), CPA had no effect (P >.2) on either live a nimal performance or meat quality. During the second trial, conducted under extreme outside temperatures (-18 degrees C), CPA-dependent reductions (P <.05) in feed intake, average daily gain, and 45-min pH in nit hogs support the possibility of interactions between malignant hyperthermia and dietary CPA on skeletal muscle calcium homeostasis and the development of PSE pork . These results suggest that this interaction may require stressful environ mental conditions or the ingestion of CPA doses much higher than occur unde r natural conditions.