Microbial populations on animal hides and beef carcasses at different stages of slaughter in plants employing multiple-sequential interventions for decontamination.

Multiple-sequential interventions were applied commercially to reduce beef carcass contamination in eight packing plants. The study evaluated microbial populations on animal hides and changes in carcass microbial populations at various stages in the slaughtering process. Sponge swab samples yielded mean (log CFU/100 cm2) total plate counts (TPC), total coliform counts (TCC), and Escherichia coli counts (ECC) on the exterior hide in the ranges of 8.2 to 12.5, 6.0 to 7.9, and 5.5 to 7.5, respectively, while corresponding contamination levels on carcass surfaces, after hide removal but before application of any decontamination intervention, were in the ranges of 6.1 to 9.1, 3.0 to 6.0, and 2.6 to 5.3, respectively. Following the slaughtering process and application of multiple-sequential decontamination interventions that included steam vacuuming, pre-evisceration carcass washing, pre-evisceration organic acid solution rinsing, hot water carcass washing, postevisceration final carcass washing, and postevisceration organic acid solution rinsing, mean TPC, TCC, and ECC on carcass surfaces were 3.8 to 7.1, 1.5 to 3.7, and 1.0 to 3.0, respectively, while corresponding populations following a 24 to 36 h chilling period were 2.3 to 5.3, 0.9 to 1.3, and 0.9, respectively. The results support the concept of using sequential decontamination processes in beef packing plants as a means of improving the microbiological quality of beef carcasses.

Dual-component video image analysis system (VIASCAN) as a predictor of beef carcass red meat yield percentage and for augmenting application of USDA yield grades.

An improved ability to quantify differences in the fabrication yields of beef carcasses would facilitate the application of value-based marketing. This study was conducted to evaluate the ability of the Dual-Component Australian VIASCAN to 1) predict fabricated beef subprimal yields as a percentage of carcass weight at each of three fat-trim levels and 2) augment USDA yield grading, thereby improving accuracy of grade placement. Steer and heifer carcasses (n = 240) were evaluated using VIASCAN, as well as by USDA expert and online graders, before fabrication of carcasses to each of three fat-trim levels. Expert yield grade (YG), online YG, VIASCAN estimates, and VIASCAN estimated ribeye area used to augment actual and expert grader estimates of the remaining YG factors (adjusted fat thickness, percentage of kidney-pelvic-heart fat, and hot carcass weight), respectively, 1) accounted for 51, 37, 46, and 55% of the variation in fabricated yields of commodity-trimmed subprimals, 2) accounted for 74, 54, 66, and 75% of the variation in fabricated yields of closely trimmed subprimals, and 3) accounted for 74, 54, 71, and 75% of the variation in fabricated yields of very closely trimmed subprimals. The VIASCAN system predicted fabrication yields more accurately than current online yield grading and, when certain VIASCAN-measured traits were combined with some USDA yield grade factors in an augmentation system, the accuracy of cutability prediction was improved, at packing plant line speeds, to a level matching that of expert graders applying grades at a comfortable rate.

Chemical dehairing of bovine skin to reduce pathogenic bacteria and bacteria of fecal origin.

A chemical dehairing process was applied to artificially contaminated bovine hide to evaluate the effect on populations of Escherichia coli O157:H7 and Salmonella Typhimurium, as well as other strains of E. coli, total coliforms, and aerobic plate counts (APC). Pieces of hide (4 cm2) were contaminated with bovine feces inoculated with both rifampicin-resistant E. coli O157:H7 and S. Typhimurium to yield a final count of each pathogen of ca. 5.0 log10 CFU/cm2, or with noninoculated feces which produced an approximate final APC of 6.0 log10 CFU/cm2 and a coliform and E. coli count of 5.0 log10 CFU/cm2. Counts of pathogens, APC, coliforms, and E. coli were conducted before and after applying the dehairing treatment. S. Typhimurium and E. coil O157:H7 populations were significantly reduced from initial numbers (5.1 to 5.3 log10 CFU/cm2) to levels below the detection limit of 0.5 log10 CFU/cm2 after chemical dehairing. APC, coliforms, and E. coli counts were also reduced significantly after dehairing, with reductions of 3.4 for APC, 3.9 for coliforms, and > 4.3 log10 CFU/cm2 for other E. coli strains. Since the hide is a major source of fecal contamination of beef carcass surfaces, chemical dehairing may be beneficial in reducing overall contamination of carcasses.

Incidence of injection-site blemishes in beef top sirloin butts.

The occurrence of damaged muscle tissue resulting from intramuscular injections of animal-health products represents a "quality control" problem and an economic loss to the beef industry. Five individual and sequential national audits of injection-site blemishes in beef top sirloin butts have been conducted at the steak-cutter level. During the most recent audit (March 1993), the incidence of injection-site blemishes in top sirloin butts was determined to be 10.87 +/- 2.99%, with an average weight per blemish of 123.39 +/- 5.48 g. A 5-point classification system used to partition the blemishes into chronological stages of the healing process suggested that the majority of the blemishes originated at the cow-calf or stocker levels, or early in the finishing period. Evaluation of blemish data by geographic location of plant-of-origin suggests that the problem occurs throughout the beef production sector.

Slaughter weight loss attributable to pregnancy in feedlot heifers.

Slaughter weight loss attributable to pregnancy in feedlot heifers was determined by immediate postmortem weighing of uteri and uterine contents of pregnant heifers. For each 10% pregnant animals within a group of slaughter heifers, the dressing percentage was reduced for the entire group by 0.66%.