Sources of contamination and effect of acid decontamination on sheep carcasses

Malpura sheep (9 months old) maintained on a complete diet containing 25: 75 roughage and concentrate were slaughtered in this study for carcass quality evaluation. Samples from walls, floors, butcher's hands, knives, live animals and ruminal surface were collected by swabbing an area of 10 cm². After evisceration, half of the carcass was sprayed with tap water (control; normal practice) and another half was sprayed with 1% (v/v) lactic acid solution (50°C, 150 ml/side). Each half carcass (control and treated) was kept at refrigerated temperature (4±1°C). Meat samples were analysed for microbial counts at 0, 4 and 8 day's storage period. The data indicated that the skin of the live animal was significantly contaminated with bacteria. The mean aerobic plate count (APC) of the live animal was significantly (P<0.05) higher (log 3.13/cm²) than other contamination sources. The bacterial numbers increased after slaughter in all the possible source of contamination sites. In floors, the number of APC reached from log 1.78 to 3.23/cm². After evisceration, there was no further increase in the APC. However, after washing with tap water (normal practice) there was a reduction in APC from log 2.89 to 2.65/cm². After washing of carcass with 1% lactic acid, a marked reduction in APC was observed and from 2.89 to 2.37/cm². After 24 hrs chilling of carcasses, the increase was pronounced in untreated carcass surfaces (3.09 cm²) as compared to carcasses treated with lactic acid (2.87 cm²). It can be concluded from the present study that the live animal itself and ruminal surface are most contaminated part and major precautions should be taken during removal of skin and evisceration. The decontamination of carcass with 1% lactic acid significantly reduced carcass contamination.