Slatted floors are popular throughout Ireland as they offer a labour and cost-effective system of slurry management that does not need bedding or regular cleaning out.
However there is clear evidence from previous studies at AFBI that beef cattle actually prefer rubber to concrete slats for both lying and standing, so rubber floors may have the potential to enhance animal welfare.
Previous work carried out at both AFBI and Teagasc have reported conflicting effects of overlaying slats with rubber on animal performance, as detailed in Table 1.
Within a DAERA funded programme of work, AFBI has recently completed a series of studies examining the effect of overlaying concrete slats with rubber for dairy-origin bulls. The rubber was clipped into position directly over the concrete slat, using a plastic rigid fixing system at each side of the slat. Furthermore, to reflect typical rearing protocols for such animals in temperate countries such as Ireland and the UK, the bulls were grazed for several months during the grazing season, before being intensively finished indoors and slaughtered at less than 16 months of age.
Key questions posed in the project were:
- How does overlaying slats with rubber affect bull performance and welfare?
- Is it economically viable for farmers to overlay slats with rubber for dairy-origin beef bulls?
A description of the studies and the age and live weight of the bulls used are presented in Table 2 and the performance of the animals in Table 3. The data from the three studies was combined and statistical analysis of this combined data gave a clear picture of the positive effect of overlaying slats with rubber on performance (Table 4).
Across the 3 trials an average of a 9kg increase in carcass weight was found in dairy-origin bulls accommodated on rubber covered slats compared with those on concrete slats (Table 4). At current beef and rubber overlay prices this equates to a payback time of 3.5 years, after which there would be an increase in profit for the producer.
Within the published literature many variables such as breed, slaughter weight, pen space allowance, group size, pre-experiment accommodation, rubber product type and diet could potentially have an impact on the effect of floor type on animal performance. Of these gender would seem to have an important role to play; whereby an effect of floor type on performance has been commonly observed in bulls but not in steers or heifers.
The reason behind these gender differences are not fully understood but may be related to the higher growth rates of bulls. Also the different production systems of rearing and finishing bulls compared with steers and heifers mean that bulls tend to have one longer housing period, compared with two shorter housing periods for steers and heifers.
Furthermore, results from the recent AFBI project indicated that the effect of floor type on performance is influenced by the diet offered. When bulls were offered ad libitum concentrates, those accommodated on rubber covered slats had a higher concentrate intake than bulls accommodated on concrete slats. In contrast, there was no difference in intake between cattle on the two floor types when the bulls were offered a diet of grass silage supplemented with 6 kg concentrate. Additionally there was no beneficial effect of changing floor type from slats to rubber or straw during the finishing period on animal performance.
Another important aspect to consider when comparing floor types is the cleanliness of cattle, since a dirtier hide is associated with a higher bacterial contamination of the carcasses. Increased dirtiness of cattle accommodated on rubber covered slats has previously been reported to be due to the lower drainage area relative to fully slatted concrete floors and this has been seen in dirtier cattle kept on perforated rubber mats. Results from AFBI’s recent project indicated that floor type had no effect on the cleanliness at slaughter of beef cattle in any of the studies.
An interesting pattern emerged in animal cleanliness in these studies (Figure 1), whereby all animals got dirtier when housed, but as they lost their winter coats animals became cleaner. There was evidence that those accommodated on rubber covered slats were cleaner than those accommodated on concrete slats at this time, even though the drainage area was reduced in rubber covered slats compared with concrete slats (18 v 24% respectively. However floor type had no significant effect on animal cleanliness by slaughter.
Commercial suppliers of rubber overlays for slats have been focused on cattle cleanliness in their design of rubber coverings for slats and the design of the rubber used in this series of studies was curved on the upper side of the rubber slat to assist removal of faeces and urine into the slurry tank below. Contrary to what we might have expected, increasing the space allowance to twice the current recommended rate had no effect on the dirtiness of the bulls.
Health and behaviour
Lameness has potential to negatively affect overall livestock productivity (and thus farm profit margins), so it was important to assess as part of the project.
Researchers in Sweden have raised concerns about welfare of cattle accommodated on fully slatted concrete floors in terms of hoof health and joint swelling, whilst German scientists have highlighted the reduced ability of cattle on slats to readily get up and down on concrete slats. On the other hand Italian researchers expressed concern that rubber flooring is not abrasive enough for sufficient hoof wear and could result in cattle with overgrown hooves.
Within the programme of work at AFBI there was less sole bruising noted in bulls kept on rubber slats compared with concrete slats. In addition, despite some evidence of greater claw dimensions in bulls accommodated on rubber flooring there was no effect on locomotion score, indicating that this degree of increased hoof net growth had no impact on walking ability.
The abrasiveness of concrete slats is likely to be linked to the age of the slats and different commercial rubber products have differing hardness and abrasiveness properties. An analysis of the bulls’ lying and standing behaviours indicated that cattle on slats took less steps and got up and down less often than those on rubber. Cattle finished on straw got up and down most often and took the highest number of steps.
These behaviours suggest that rubber flooring is a potential compromise between concrete slats and straw bedding in terms of animal welfare.
- Concrete slatted floors are a practical option in terms of labour and slurry management, particularly where straw-bedding is not economically viable.
- Increased daily live weight gain is likely to be found in bulls accommodated on slats overlaid with rubber, making this is an economically viable choice.
- Additionally rubber floors provided a more comfortable floor, allowing bulls to get up and down more easily; cleaner cattle and less hoof bruising.
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