Assessment of cleaning systems for cattle

Summary

Dags (concretions of dung, hair, soil, urine, sugars and straw) form on the hides of feedlot cattle during periods of extended wet weather, and are attached to the animal by hair alone. The effective removal of dags from the hides of cattle remains a significant issue for the livestock industry in Australia. There is a requirement for feedlots and processors to remove dags and present clean cattle for slaughter. This cleaning is undertaken to reduce the likelihood of microbial meat contamination and irreversible damage during leather processing.

The aim of the project was to provide relevant information that industry could use in deciding on the future use of a cleaning method in their own production system. The project assessed the available range of cleaning systems for effectiveness in removing dags and associated microbiological contamination, occupational health and safety issues, animal welfare issues and the effects on meat and hide quality.

Three trials were performed on cattle. One of these, a smaller trial of 20 cattle, was conducted in summer to assess the effects of cleaning treatments on dust load and subsequent final microbial load of carcasses from those cattle. Two further trials were undertaken in winter to assess the same cleaning treatments in high dag load season. Treatments were assessed by measuring:

• effectiveness of dag removal, assessed visually utilising the UK Clean Livestock Grading System
• effects on microbial levels on carcasses in the chiller.
• costs of applying the treatment.
• effects on animal welfare.
• effects on occupational health and safety.
• effects on meat quality

The major findings of the project were:

• there is no direct correlation between the dag loading of the live animal and the microbiological quality of the carcasses.
• the level of E.coli on the carcasses tested was very low, and well within the USDA Mega-Reg requirements.
• all treatments in the three trials were effective at reducing the dag loading of live animals, assessed using the UK Clean Livestock Grading System. Only shearing totally eliminated the dag loading.
• lowest stress was seen in animals in the spray wash and detergent, spray wash and pre-shear/shear groups.
• 0 H & S risks are lowest in the spray wash, wash and detergent, RRDRS and the post slaughter air knife treatments
• lowest costs were seen in the wash and detergent treatments and the two post slaughter treatments (air knife and Parke Rota Shear™).