No abstract

The use of the creatine kinase-luciferase (CK-L) coupled reaction for porcine blood CK determination was studied. Adenosine triphosphate produced by CK is reacted with firefly L light-producing system. The method permits determination of CK in blood as opposed to traditional methods which require plasma or serum. The luciferase procedure was applied to nine barrows each of purebred Pietrain and Yorkshire (Y)-Minnesota No. 1 (M)-Pietrain (P) breeding [Yx M(PX M)]. Pietrain pigs exhibited higher (P<.05) ear-blood CK after transportation at 83 kg live weight, but not after exercise at an earlier age (40 kg live weight). Pietrain pigs exceeded YXM(PXM) pigs for longissimus (P<.01) and trapezius (P<.05) muscle pH decline rates, longissimus area (P<.01), ham plus loin percentage (P<.01), and percentage of four lean cuts (P<.01). YXM(PXM) pigs exceeded Pietrains for longissimus subjective color, morphology and marbling (all P<.01)and backfat thickness (P<.05). Intraclass correlation coefficients between blood CK following transportation stress and longissimus pH (20 min postmortem) were significant (P<.05) for Pietrain (r=--.67) and Y• M(PX M) pigs (r=-.79). Highly significant (P<.01)correlation coefficients were noted between serum CK, as determined by the Rosalki procedure, and blood CK, as determined by CK-L for Pietrain (r=.93) and for Yx M(PX M) pigs (r=.99). (

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 utilization of lactate since the stress susceptible PxP pigs ranked high in both characteristics.