Emergency slaughter and regular slaughter: prevalence of post mortem lesions and effect of risk factors
This retrospective study collected and compared information about the occurrence and typology of pathological lesions observed throughout the post mortem inspection of cattle (focusing on dairy cows) that have undergone emergency slaughter compared to those obtained from animals subjected to regular slaughter. Data from 16,899 dairy cows (6761 of them being submitted to emergency slaughter – ES, and the others to regular slaughter - RS), were recovered at an industrial plant located in Lombardy (Northern Italy) through a two years period. Lesions were classified based on the organ affected (lung, heart, liver, kidney and other locations) and on the typology. General and specific prevalence was calculated, and the effect of animal age and slaughtering season was analyzed.
The general prevalence of lesions determining the condemnation of the viscera and/or of the whole carcasses was 9.2% for both RS and ES animal populations. Significant differences were detected considering single organs, with higher prevalence in RS animals for lung (2.0% vs 1.6%), heart (1.0% vs 0.6%), liver (5.8% vs 2.6%) and kidney (1.5% vs 0.7%) lesions, whereas a significantly higher rate was observed in ES animals (5.3% vs 1.0%) for lesions in other locations (including muscles). The most frequently detected lesions in the organs were pneumonia (lung), pericariditis (heart), steatosis an (liver), and interstitial nephritis (kidney); despite of their prevalence, these lesions were hardly associated to whole carcass condemnation, that occurred mainly in the presence of purulent/gangrenous lesions. Lesions in “other” locations were mainly represented by alteration of meat characters (infiltration of serum/blood, altered flesh characteristics), that were frequently associated to the condemnation of the whole carcass.
Considering the slaughtering season, a significantly higher prevalence of lesions was observed in autumn for all the organs inspected in both RS and ES animal populations. Finally, animals’ age influenced significantly the prevalence of lesions, with an increasing rate in older animals for liver and kidney lesion, while for lung and heart lesions, an increase was observed until 5-7 years-old category, and a slight decrease was evidenced in older animals. The lesions in other locations followed an opposite trend, with significantly higher prevalence in younger animals (< 3 years of age) and a gradual decreasing trend.
The data obtained showed the utility of feedback of data collected at slaughter to direct the inspection procedures, especially in higher risk situations (such as emergency slaughtered animals) and to improve farming practices to reduce the impact of health/welfare problems occurring in the population of dairy cows.