INJECTION-SITE LESIONS - INCIDENCE, TISSUE HISTOLOGY, COLLAGEN CONCENTRATION, AND MUSCLE TENDERNESS IN BEEF ROUNDS

The national incidence and extent of injection-site lesions in the mus cles of the round were determined via audits conducted at retail store s and in purveying establishments. Two additional experiments were con ducted to examine the subsequent effects of pharmaceutical administrat ion on tissue histology, soluble and insoluble collagen concentration, and muscle tenderness in beef bottom-rounds. Injection-site lesion in cidence in beef round cuts audited at retail (n = 3,538) and in steak- cutting facilities (n = 15,464) was 8.45 and 10.04%, respectively, wit h an average lesion-trim of 314.7 and 191.59 g, respectively, in these two studies. Lesion classification revealed that 93.20 and 99.91% of lesions reported for the retail and purveyor audits, respectively, wer e chronologically aged lesions. Overall, 19,002 round cuts were examin ed, and injection-site lesion incidence (nationally) was 9.74%, wherea s lesion-trim averaged 211.8 g. Warner-Bratzler shear measurements tak en near lesions and in areas 7.62 cm from the lesions were higher (P < .001) for lesioned, than for control bottom-round steaks. Warner-Brat zler shear values for lesion cores were 3.5 times greater than those i n paired control (nonaffected) steaks. Concentrations of insoluble and soluble collagen were much higher (P < .001) at the site of the lesio n center in lesion-afflicted vs control steaks. Histological determina tions of the relative proportions of muscle, connective tissue and fat to a distance of 5.08 cm from the site of the lesion center confirmed that severe disruption of muscle tissue constituents and architecture had occurred. Injection-site lesions occur at an unacceptable frequen cy in the muscles of the round, and severe tissue changes accompany th ese lesions that can dramatically affect tenderness of those cuts.