Modern commercial sow facilities are built with durability and cleanliness in mind. Floors in these facilities are often built using slatted concrete to ensure better ease in cleaning and manure management. Unfortunately, with such flooring systems, we often see an increase in lameness and injury to the sow. Lameness is not only an animal welfare issue due to the pain associated with lameness, but it can also have significant economic impact to the producer due to poor reproductive efficiency, piglet health and sow longevity. Research is needed to identify how to mitigate the negative effects of concrete slatted floors while maintaining the ability to effectively clean these production facilities. Adding temporary and mobile substrates such as rubber mats may be one solution to minimize lameness severity and increase sow longevity and productivity. Therefore, the objective of this study was to investigate the effect of rubber mats in farrowing crates on performance and behavior of lame and non-lame commercial sows.

The study took place on a 5000 sow commercial swine farm. All sows were evaluated in group pens prior to enrollment of study by an experienced veterinarian. Sows with any evidence of disease or injury (with the exception of lameness) were ineligible for enrollment. At enrollment, sows (100-109 day of gestation) were evaluated for lameness by one trained veterinarian using a 1-3 walking and standing lameness scoring systems (1. Non-lame, 2. Lame, and 3. Severely lame; non-weight bearing on one leg). Sows were blocked by parity and assigned to one of four treatments based on their lameness score at enrollment 1) Lame Control (LC; n=45); 2) Lame Rubber Mat (LR; n= 48); 3) Non-Lame Control (NLC; n= 61); and 4) Non-Lame Rubber Mat (NLR; n =59). The control treatment (C) consisted of a standard farrowing crate with slatted flooring in the sow and piglet area, while the rubber mat treatment (R) consisted of a farrowing crate fitted with a perforated rubber boar mat (Heavy duty rubber mat, FarmerBoy Ag, $78.08). Mats covered an area from the front of the sows shoulder to their hindquarters and remained in the farrowing crate until weaning. Once piglets were weaned and sows moved back to breeding, mats were removed from all crates, power-washed and disinfected between each use and reused the following week.

 
Measures collected
Lameness scores were collected weekly for each sow by a trained veterinarian utilizing the standing scoring system described previously. To evaluate the effect of lameness between the time of farrowing to the time of weaning, sows were grouped into one of four lameness categories at the end of lactation; 1. Lame-Lame (LL); sows receiving a lameness score ≥1 in gestation and at weaning (n=39); 2. Lame-Non-lame (LN; sows receiving a lameness score of ≥1 in gestation and a score of 0 at weaning (n=51); 3. Non-lame-Non-Lame (NN); sows receiving a lameness score 0 in gestation and at weaning (n=82); and, 4. Non-lame- Lame (NL); sows receiving a lameness score of 0 in gestation and a score ≥1 at weaning (n=25).

Additional measurements included sow body weight, body condition score, lesion scores, and behavior (time spent lying, standing, sitting, drinking, nursing or eating). Measurements were collected weekly until weaning. Production data was also collected and included total piglets born, number born alive, stillborns, mummies, total weaned, total cross-fostered and f piglet mortality (low viability, deformed, micro piglet, spraddle legged, starved, rupture, crushed and injured).

 
Results
Lameness severity was not affected by the presence of a rubber mat placed in the farrowing crate. Lameness was also not affected by sow body weight or body condition. Lesions present on the skin of the sow decreased over the time the sow was housed in the farrowing crate and the presence of the rubber mat did not increase the number of lesions. The decrease in lesions over time is likely a result of sows being housed individually (eliminating aggressive interactions between sows) and providing time for the lesions to heal.
 
Lameness did not have an effect on the total piglets born, number of piglets born alive, number of stillborn, or mummified piglets per litter. No differences in average piglet weight at farrowing was found but sows entered the farrowing crate lame weaned piglets with 0.6 kg lower average weaning weight compared to other sows. Piglets housed in farrowing crates with a rubber mat had a 0.4 kg lower average weaned weight and 0.8 more piglets were laid on.
 
These findings suggest that the rubber mat used did not impact lameness in farrowing and lactating sows and the presence of a rubber mat resulted in greater incidence of laid on pigs. This may be most likely due to insulating properties of the rubber mat and the desire for the piglets to seek out a warmer environment within the crate. The placement of the rubber mat near the sow may be the likely reason we saw an increased in laid on pigs. Further research is needed to be able to properly assess the potential use of rubber mats as a flooring substrate to mitigate lameness in farrowing crates.