Lactate metabolism by cardiac muscle and liver from Pietrain and Minnesota No. 1 pigs and their reciprocal crosses.

The objective of this study was to determine the intrinsic capacity of heart and liver to utilize lactate in porcine breeds of varying degrees of stress-susceptibility. Experimental animals were stress susceptible Pietrain barrows (Px P), stress resistant Minnesota No. 1 barrows (Mx M) and barrows from reciprocal crosses of these breeds (P• and M• P). Parameters of postmortem muscle quality generally characterized P• M pigs as exhibiting values intermediate between the pale, soft, exudative musculature of P• P pigs and the normal morphology of the Mx M breed. Muscle quality in M• P pigs tended to be close to M• pigs. No significant differences were noted for the capacity of cardiac muscle to convert lactate to CO2 expressed as micromoles CO2 per gram per hour, or on a total heart weight basis. CO2 production from lactate by liver expressed as micromoles CO2 per gram liver per hour was higher (P<.05) in Px P than Mx P and Px M but not significantly different from MxM; MxM exceeded (P<.05) MxP. Expressed as micromoles CO2 per total liver per hour, Px P pigs exceeded Px M and MX P (P<.05) but were not significantly greater than MxM. It was concluded that lactic acidosis during the stress syndrome is not related to deficient hepatic or cardiac util ization of lactate since the stress susceptible PxP pigs ranked high in both characteristics. (