VARIABILITY AND DETERMINANTS OF CARCASS BACTERIAL LOAD AT A POULTRY ABATTOIR

Roaster chicken carcasses (2,928) were collected from the evisceration line of a poultry abattoir over a 5-month period and identified as to the lot (truck load) and supplier. Bacterial load was determined by m echanically rinsing each eviscerated carcass in sterile water and then using an automated hydrophobic grid membrane interpreter system to ob tain die log10 most probable number of aerobic bacteria per gram of ca rcass. Analysis of variance demonstrated that the between-carcass, bet ween-lots-within-supplier, and between-supplier components of variabil ity in bacterial load represented 73.2, 14.2, and 12.6% of the total v ariability, respectively. There was a significant (p < 0.001) supplier and lots-within-supplier effect on bacterial load of carcasses. A reg ression model demonstrated that bacterial load of lots significantly ( p less-than-or-equal-to 0.05) decreased with increasing hours of opera tion of the evisceration line. Factors in the model which were signifi cantly (p less-than-or-equal-to 0.05) associated with increased bacter ial load included longer crating and holding times, higher visible con tamination scores, slaughter during winter months, higher outdoor temp eratures, and slaughter of lots composed of only pullets. The model ex plained about 23% of the variability in bacterial load.