The three keys to preventing paw lesions are to ventilate poultry houses for relative humidity (RH) in order to prevent moisture build-up around the drinker/feeder lines and the sidewalls, manage drinkers to prevent leaks, and acidify the litter surface to neutralize ammonia. In houses that are ventilated through a curtain crack or fixed inlet boards ventilating for RH is difficult as air entering the houses does not have sufficient velocity to flow across the ceiling but rather drops straight to the floor dumping moisture along with it.
In a study conducted by Weaver and Meuerhof (1991), raising birds at a 45% RH compared to a 75% RH reduced paw lesions substantially. Birds in the 75% RH group had three times the ammonia burns on the feet and the severity of the lesions was greater than those birds raised in the 45% RH group. In addition to decreasing moisture at the litter surface, acidification of the litter with PLT® litter acidifier to neutralize the ammonia that is in solution is also important. Using the appropriate rate of PLT® for the litter age and applying a little extra in the damp areas will help to neutralize the ammonia in solution.
Scoring System For FPD
In the European Union, FPD scoring is often used as an indicator of animal welfare conditions during the live production phase. The FPD scoring systems reported in the poultry literature such as the Ekstrand score (Ekstrand et al. 1998) and the modified Ekstrand score (Pagazaurtundua and Warriss, 2006) are the ones that have been developed in the EU strictly for this purpose. In these scoring systems, the total surface area that the lesions cover determines the foot score rather than the depth of the lesion. These scoring systems are also designed for use at processing in order to evaluate the performance of farms that may not be vertically integrated with the plant. For processing plants in the United States, however, paws are evaluated for their export potential and not for animal welfare reasons. The USDA grading measurements are far stricter than the animal welfare measurements of the EU. USDA classifies ammonia burns as a “resolving or healing wound” and allows 13 small (≤ 0.5 inches), 6 medium (> 0.5 to 1 inch), or 3 large (> 1 inch) lesions per sample size of 50 randomly selected feet. In order for a FPD scoring system to be useful in the US, a scale matching the USDA grading system is needed. In addition, a scoring system that can be used in the field on young birds as a predictor of how a flock will grade at processing is useful.
After several evaluations of a large number of birds on a wide variety of farms, the following three score system was devised for scoring birds at 7-10 days of age in order to predict how a flock will grade at the processing plant. Scoring birds at this age allows remedial action to be taken to prevent further deterioration of the paws, as well as makes the catching and handling easier on both the birds and the scorer.
- Only the underside of the bird’s foot is scored. Paws that have attached dirt should be washed prior to scoring.
- Both paws are scored with the higher score recorded.
- A minimum of 30 birds per house should be evaluated.