Crop Extraction Load and Efficiency of Crop Removal During Manual Evisceration of Broilers: 2. Influence of Age, Gender, and Direction of Extraction

Abstract

A series of experiments evaluated the influences of gender and age, the direction of crop extraction on the maximum load required for manual removal of the crop, and the resulting incidence of crops being removed intact. Male and female broilers at 5, 6, 7, and 8 wk of age were electrically stunned, bled, scalded, and defeathered prior to removal of the crop through the thoracic inlet toward the vent or avoiding the thoracic inlet by removal toward the head (n = 16 per gender, age, and direction). The maximum load required to remove the crop increased with age and body weight but at a slower rate than body weight. Values for males were 21% higher than those for females over the 4-wk period. When maximum load was adjusted by weight at slaughter, the gender difference was no longer significant. The maximum load required to extract the crop toward the head was 16% less than through the thoracic inlet. This difference was present for male and female broilers at each age sampled. Correlations between live weight and maximum load were higher for crops pulled through the thoracic inlet (r = 0.78) than for those removed toward the head (r = 0.57) and also were higher for crops removed intact (r = 0.84) than for those crops that broke (r = 0.66). Over the 5-to-8-wk period the incidence of crops removed intact that were pulled through the thoracic inlet was 69% for females and 59% for males, compared to significantly higher incidences of intact crop removal obtained for crops removed toward the head, which were 92% for females and 98% for males. These results suggest that the maximum load to extract the crop increases at a slower rate than live weight for both female and male broilers from 5 to 8 wk of age.