Factors Affecting The Cleanliness Of Cattle Housed In Buildings With Concrete Slatted Floors

Summary

• From a series of experiments at Grange Research Centre, cattle were cleanest at housing in the autumn, however, within 3 to 4 weeks of housing on concrete slats and fed with a diet of grass silage, cattle were dirtiest, with the majority of the cattle in category 4 or 5.
• Cattle tended to be cleaner in the late March, early April period as they shed their winter hair coat.
• Cattle fed concentrates plus straw were significantly cleaner at slaughter compared to similar cattle offered grass silage plus concentrates.
• Cattle housed indoor on slats during the summer were cleaner than cattle on similar diet and accommodation during the winter.
• High dry matter silage produced cleaner cattle than did low dry matter silages.
• Back and tail clipping of cattle at the commencement of the winter finishing period did not have any positive effect on cleanliness score or liveweight gain when the cattle were accommodated in well ventilated slatted floor houses.
• A survey of 19 farms specialising in finishing cattle failed to show any correlation between stocking density, solid floor area or level of concentrate feeding on the cleanliness of finishing cattle.
• A survey of 36 finishing units, designated as producers of "clean" or "dirty" cattle at slaughter, found that units with clean cattle had houses which were in general well ventilated, had A-type roofs with an open ridge outlet and in general the grass silage offered was a higher dry matter. In contrast, finishing units with dirty cattle tended to be poorly ventilated and the grass silage offered had a lower dry matter.
• Overall in the survey cattle cleanliness score was not affected by stocking density (2.0m ² 3.8m ²) or the proportion of solid floor area in the pen.
• Cattle accommodated on gang slats were dirtier than those accommodated on single slats.

Introduction

Regulations governing the level of cleanliness of animals presented for slaughter were introduced by the Department of Agriculture and Food in Ireland in February 1998. These regulations outline five different categories of cleanliness ranging from 1 (clean) to 5 (very dirty) by which cattle presented for slaughter are assessed. These categories are similar to those presented in the British Meat Hygiene Service Clean Livestock Policy (1997). Categories 1 to 4 are accepted for slaughter. Category 4 animals with heavy amounts of adherent dirt/faeces on the primary sites (Figure 1) are accepted for slaughter after some changes in dressing procedure are carried out. Category 5 animals are not accepted for slaughter.

Figure 1 Primary sites for cleanliness measurements

There is contradictory evidence with respect to the effect of dirtiness of the hide of the animal on carcass microbial contamination. Ridell and Korkeala (1993) and Newton et al., (1978) demonstrated that there was a direct correlation between the microbial load on the cattle hide and on the carcass surface. Irrespective of the experimental evidence on this issue, the presentation of clean animals at slaughter, is desirable in order to minimise the introduction of a reservoir of pathogenic bacteria into the meat processing plant (Hadley et al., 1997).

There has been little experimental work carried out on factors affecting dirtiness of cattle. A survey by Scott and Kelly (1989) showed that cattle from any one of a number of housing systems can have dirty hides. They noted (contrary to popular opinion) that straw bedding systems were not necessarily the cleanest, neither were slatted floors the dirtiest. There was a general trend for animals to appear cleaner later in the season (March - April) and this was thought to be due to a combination of factors especially the loss of the winter coat.

This project was undertaken to determine what were the main factors affecting the cleanliness of cattle prior to slaughter and the following areas were investigated:-

1. Effect of time of year and type of diet on the cleanliness of finishing cattle.
2. Effect of tail clipping and back clipping at housing on cattle cleanliness score.
3. Survey of cattle cleanliness on 19 farms which specialise in finishing cattle.
4. Survey of farms producing finishing cattle which are designated to present "clean " or "dirty" cattle at slaughter.

Effect of time of year and diet on cleanliness of finishing cattle

The objective of the study was to examine the effect of cattle housed on concrete slats on category of cleanliness in respect to time of year, type of diet fed and duration of housing. The cleanliness scores were assessed, by a trained observer using photographic reference material provided by Department of Agriculture and Food, on cattle used in finishing experiments at Grange Research Centre.

Effect of back clipping and tail clipping on cleanliness score and performance of finishing cattle

Reports from Scotland indicate that back and tail clipping of finishing cattle at the start of the winter feeding period results in cleaner cattle and improved animal performance. Clipping the back of the animal allows the animal to dissipate heat and to sweat less, thereby, reducing the risk of dirt accumulation. In order to test the hypothesis that this had a positive effect on cleanliness and animal performance, finishing animals were assigned to either a control or a clip treatment.

Experiment 1. 72 Ch X Fr steers with a mean weight of 487 kg were accommodated on single concrete slats (6/pen) in an A type house which had good ventilation. Within each pen 3 animals were randomly selected for back (15 cm wide from withers to tail base) and tail clipping and the other 3 animals were assigned as controls.

Experiment 2. 28 three-quarter Continental steers with a mean weight of 560 kg were accommodated on concrete gang slats (5 to 7 per pen) in a A type house which had good ventilation. Within each pen animals were randomly selected for back and tail clipping and the remaining animals were assigned as controls. Data was analysed using ANOVA.

Both experiments commenced in the first week of November and were completed by the first week of March after a 120 day period indoors with the animal fed a diet of grass silage plus concentrates. The Department of Agriculture, Food and Rural Development Category 1 to 5 scores for cleanliness was used to monitor the animal at start and throughout the experimental period. Back and tail clipping at the commencement of the winter feeding period did not have any effect on cleanliness score or liveweight gain (Table 1).

Survey of cattle cleanliness on 19 selected farms specialising in finishing cattle

A survey was undertaken on 19 commercial farms (437 cattle) specialising in finishing cattle to determine what on-farm factors affect the cleanliness of cattle. The farms were surveyed in late February and early March (1991). The survey compared number of animals per pen, space allowance per animal, amount of concentrate fed, void floor area and solid area at front and back of pen, with a cattle cleanliness score of Category 4 and 5.

Survey of Factors Affecting the Cleanliness of Cattle

There is usually not a cleanliness problem with cattle sold off pasture, as they will normally be dirt score Category 1 or 2. Dirty cattle may come from indoor housing in the months of December through to March. However, after 4 to 6 weeks indoors a large proportion of cattle will be in Category 4 or 5. Thereafter the scores begin to decrease and this trend continues through late March/early April, being associated with the shedding of their winter coats. The production of clean cattle may be a problem as the accommodation used is mainly concrete slatted floors (loose straw bedded accommodation is not feasible on a wide scale) and the most common finishing diet is unwilted grass silage plus concentrates.

Different sources have suggested that the type of feed may affect the cleanliness of the animal e.g. it was stated that lower dry matter silage diets may cause wetter faeces and thus, dirtier animals. Anecdotal evidence for years suggests that the stocking rate of animals on slats affects the cleanliness of animals. In order to determine the actual level of dirt on cattle accommodated on concrete slatted floors a survey of 46 cattle finishing units was undertaken.

Acknowledgements

Our appreciation to our colleagues at Grange Research Centre for the provision of animals for the various experiments. Our appreciation to our Teagasc Advisory colleagues for the selection of farms for the various surveys and to the farmers for their kind co-operation. The skilled technical assistance of Mr. D. Prendiville is gratefully acknowledged.

References

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