Injection-site lesions in beef muscles and study of the chemistry responsible for green discoloration

Damaged beef muscle tissue resulting from intramuscular injections of animal-health products represents a “quality control” problem. In 1998, 31% and 60% of rounds from carcasses of beef cattle and dairy cattle, respectively, had an injection-site lesion. Frequency of lesions in rounds from carcasses of beef cattle declined 5 percentage points (P < 0.05) between 1998 and 1999, and 6 percentage points (P < 0.05) between 1999 and 2000. Frequency of lesions in rounds from carcasses of dairy cattle declined 9 percentage points (P < 0.05) between 1998 and 1999, and 16 percentage points (P < 0.05) between 1999 and 2000. The national incidence of injection-site lesions in top sirloin butts (n = 240,080) decreased (P < 0.05) between November 1995 (11.4%) and July 2000 (2.1%). During the 2000 National Beef Quality Audit, concern was raised by a major packer relative to a ‘greening’ of injection-site lesions located in muscles of chucks packaged in a high-oxygen environment. Fifty steers were vaccinated with Conquest 5K and allocated to one of two groups; control or vitamin E supplementation for 60 days. Following boxed storage and retail display, 80% of control steaks and 96% of vitamin E steaks had a green injection-site lesion present. Although results suggested that vitamin E supplementation may delay onset of the chemical reaction causing greening of injection-site lesions when packaged in high-oxygen, modified atmosphere, and may reduce the degree of oxidative rancidity formation, supplementation does not eliminate the ‘greening’ reaction. Combinations of myoglobin (Mb), copper sulfate (CuSO₄), hydrogen peroxide (H₂O ₂), vaccine, and aluminum hydroxide were made and subjected to high partial pressures of oxygen. In phase II, combinations of Mb, copper (Cu), sodium sulfide (NaS), sodium sulfite (NaSO₃), sodium sulfate (NaSO₄), and H₂O₂ were made at pH 7.2 or 5.5 and subjected to either low or high partial pressures of oxygen. Based on phase I results, it was concluded that the green color could be a result of CuSO₄ or H₂O₂. Results from phase II indicated that the ‘greening’ reaction observed in injection-site lesions of the chucks was a result of the reaction between myoglobin, copper, and sulfur.