Crop extraction load and efficiency of crop removal during manual evisceration of broilers: 1. Evaluation of stunning voltage and method of bleeding

Attention has been refocused on the mechanics of crop removal during evisce ration for the purposes of minimizing crop breakage and leakage of contents , which potentially contaminate the carcass. Experiments were conducted to evaluate the influence of stunning voltage and bleeding conditions on the i ncidence of intact crop removal and the maximum load recorded during manual evisceration of male broilers. Stunning voltages of 12, 50, or 200 V or 12 V followed by post-kill stunning were applied at 6 or 7 weeks of age. Carc ass positioning for automated and manual bleeding, in addition to head remo val prior to or during picking, was also evaluated, Stunning voltages did n ot influence the maximum load required to remove the crop intact (3.47 to 3 .50 kg at 6 weeks and 4.14 to 4.64 kg at 7 weeks), However, the incidence o f crops removed intact at 7 weeks was higher for those stunned at 12 V and 12 V plus post-kill stunning (84%) than for those stunned at 50 and 200 V ( 62%), This difference in the incidence of crops removed intact was not obse rved when repeated with broilers at 6 weeks of age that were stunned at 12 and 50 V (76%), Automated head positioning for bleeding or head removal pri or to or during picking did not alter the incidence of intact crop removal (76 and 80%, respectively) when stunned at 12 V, Less load was required to extract intact crops than to extract crops that ruptured during evisceratio n, These results further support previous observations [1] that the crop ap pears to rupture during evisceration not because of weakness but because of greater adhesion.