Foot Pad Health as Part of On-Farm-Monitoring in Turkey Flocks

Abstract

Currently, there is no consistent approach to on-farm and post-mortem foot pad (FP) assessment in turkey husbandry in sampling of both feet, sample sizes of birds and scoring schemes during the production period. Therefore, in a field study, 11,400 turkeys, i.e., 22,800 feet, were macroscopically scored at 4-week intervals, 60 birds per flock per date, in accordance with the scale system of Hocking et al. ( 1 ). Spearman's rho was calculated between the foot pad dermatitis (FPD) score of both feet of an individual turkey. Sample size for FPD monitoring was calculated for several flock sizes, considering expected FPD prevalence and the error and confidence level (α = 0.01, 0.05, 0.1). To compare macroscopic to histological findings, ten excised FPs were histopathologically investigated by hematoxylin & eosin staining. To align manual macroscopic FPD evaluations with a technical system, 20 photographic images of FPD were measured using the ImageJ program. The scores of both feet of an individual turkey correlated between r = 0.252 and r = 1.000. Thus, both feet of a bird should be monitored, while the worse foot should be evaluated. As an exemplary sample size for on-farm FPD assessment, 77 turkey poults were calculated in a flock of 4,000 birds with an expected FPD prevalence of 40% and α = 0.1. The sample size of monitored birds within a flock should differ and depend on flock size and expected FPD prevalence. Histopathological findings showed normal and non-affected structures of a macroscopic Score 0 and a moderate ulcer of the macroscopic Score 1 and Score 2. The applied assessment scheme should distinguish first alterations and scar tissue as separate scores to differentiate the need for management intervention vs. the success of management measures that were already implemented. FPD affected areas were given lower Scores and assessed to be healthier when evaluated by an image system, compared to a manual assessment. Furthermore, with regard to an increase in camera-based assessments, the boundary of the metatarsal pad needs to be clarified. In conclusion, a new scoring system is required, as the size of the FP cannot be clearly defined and different tissue textures, as well as valid sample sizes are not currently sufficiently considered.

Walking on Tiptoes: Digital Pads Deserve Increased Attention When Scoring Footpad Dermatitis as an Animal Welfare Indicator in Turkeys

“…Ulcerations are described as a loss of the epidermis, usually associated with an inflammatory reaction ( 18 ). According to a study by Stracke et al ( 14 ), there is a link between the occurrence of ulcerations and the size of the lesion on the metatarsal pad, findings which are in agreement with Toppel et al ( 13 ). Similar results were observed for broiler chickens ( 19 , 20 ).…”

“…Even if the inclusion of scoring on the digits should be easy to apply, a separate evaluation of the digital pads would ease the manual evaluation in case of a technical breakdown. Besides implementing the digits, using the total foot as reference could refine existing automatic assessment methods, especially regarding recent discussions on the correct definition of the size of the metatarsal pad ( 13 ). As the results in this study provide strong correlations between the standard FPD scoring system and FP/RA1 (using alterations on the metatarsal pad in relation to the total foot), this could be a good alternative.…”

“…In order to ensure reliability (which is essential in a scientific context, but also plays a great role when focusing on international market competition), such a system, especially when practically used at the slaughterhouse, should be clearly defined, results should be repeatable between different classifiers and it should be quick and easy to use. The five-point scoring system proposed by Hocking et al ( 11 ) fulfills all these criteria ( 11 , 13 , 14 ).…”

“…Image analysis seems to be a promising approach to automatically evaluate FPD at the slaughterhouse, first systems of which have already been used for broilers ( 25 , 26 ). In German slaughterhouses, a similar technique is employed for turkeys ( 13 ), with the classification of severity levels being based on the standard scoring system of Hocking et al ( 11 ). In this latter study, the authors state that integrating alterations on the digits might improve the quality of FPD evaluation.…”

Automatic Assessment of Keel Bone Damage in Laying Hens at the Slaughter Line

“…They are a cheap, non-contact and cost-effective tool, and have already been used to monitor diverse livestock health and behavior measures (reviewed by [ 18 , 19 , 20 ]). Automatic, image-based assessment systems are routinely applied to, e.g., the evaluation of foot pad lesions in broilers and turkeys [ 21 , 22 , 23 ]. Even though some of the keel bone fractures, which are not associated with deviations from the straight line or clearly visible callus formation, are not detectable by visual inspection (and only to a limited degree by palpation), a major part of KBD, including deviations and thereby fractures, is clearly visible and therefore a good candidate for image processing.…”