Abstract: A method for assessing the tenderness of meat from an animal, comprising the step of testing the animal for the presence or absence of a genetic marker selected from the group consisting of: (1) an allele of the gene encoding calpastatin (CAST) associated with peak-force variation or genetic variation located other than in the CAST gene which shows allelic association with the CAST allele; and (2) an allele of the gene encoding lysyl oxidase (LOX) associated with instron compression of the semitendinosis muscle or genetic variation located other than in the LOX gene which shows allelic association with the LOX allele.

Abstract: Bovine respiratory disease (BRD) complex, shipping fever, or pneumomic pasteurellosis, is a multifactorial disease whereby a combination of viral infection, adverse environment and poor immune status may combine to predispose animals to bacterial infections. The exotoxin, or leukotoxin (Lkt), may contribute to pathogenesis by impairing the primary lung defenses and subsequent immune responses or by causing inflammations as a result of leukocyte lysis. The present invention provides a modified microorganism which produces an Lkt toxin, wherein said Lkt toxin is partially or fully inactivated. In a further embodiment of the present invention, there is provided a modified microorganism wherein an Lkt toxin operon including an Lkt structural gene and/or a post transational activator of the organism is partially or fully inactivated. The present applicants have found that a precursor of Lkt toxin has reduced toxic activity.