Effectiveness of hind hock rinsing as a process hygiene intervention in bovine slaughter

Bovine hind hocks represent a critical contamination site during slaughter due to their complex anatomical structure and exposure to organic contamination. Therefore, this pilot study assessed the effect of a targeted potable water rinsing treatment applied immediately after distal pre-skinning on microbiological indicators and macroscopic contamination under commercial slaughterhouse conditions. Ten carcasses were assigned to the treated (T) group (manual potable water rinse at 4-6 bar for 5 seconds per limb), while 10 were assigned to the control (C) group. For each group, the same carcasses were sampled at the beginning of the slaughter line (BSL) immediately after distal pre-skinning and at the end of the slaughter line (ESL) by sponge swabbing 6 predefined hock sites to quantify total viable count (TVC), Escherichia coli and Enterobacteriaceae, and to detect the presence of Salmonella spp. and Shiga toxin-producing E. coli. A visual assessment of macroscopic defects was performed on 800 hocks (400 per group). The T group showed significantly greater reductions than the C group for TVC (-1.16 vs. -0.60 log10 CFU/cm²), E. coli (-0.79 vs. -0.37 log10 CFU/cm²), and Enterobacteriaceae (-0.49 vs. -0.01 log10 CFU/cm²). Pathogens detected at BSL were not detected at ESL in either group. Visual non-compliances were lower in the T than the C group (9.8% vs. 24.8%; p<0.001). Within the limitations of this single-plant pilot study, localized hind hock rinsing appears to be a promising supplementary process hygiene intervention associated with reduced microbiological indicators and visible contamination. Further multi-site validation is warranted.