Characterizing the spatial distribution of woody breast condition in broiler breast fillet by compression force measurement

Accurate and objective distinction of the varying severity of woody breast (WB) myopathy is an ongoing concern in the poultry industry due to its significant economic impact. WB myopathy, characterized by abnormal tissue hardness and rigidity in the breast ( Pectoralis major ) muscle of broilers, is distributed heterogeneously in its location throughout the fillet. Past studies examined the heterogeneity of WB myopathy throughout the fillet but only investigated a few locations (≤ 5). In this study, we conducted compression force (CF) measurements at varying numbers of locations per fillet, ranging from 10 to 38, depending on the probe sizes (6, 13, and 25 mm diameters) and instrument types (a texture analyzer and a custom robotic force sensor). CF and contact pressure (CP) values were analyzed at both the individual contact location level and the 2D fillet-image level to study the spatial distribution of WB myopathy. The location-level analysis was conducted using statistical methods such as the ANOVA test, whereas the image-level analysis involved 2D spatial interpolation of measured CF data points, the creation of 2D heatmaps to visualize CF values across the entire breast fillet, and the prediction of woody breast percentage (WB %) per fillet. The results showed significant distinctions in the output of the 25 mm probe when visualized using the heatmap, highlighting variations among WB-affected regions within a fillet and across different WB categories. In contrast, the other two probe sizes did not exhibit such pronounced heterogeneity. The results of the WB % prediction indicated that, when using the 25 mm probe, the WB % values ranged from 16% for normal breast fillets to 35% for moderate WB fillets and 50% for severe WB fillets. Similar increasing trends in the ranges of WB % values were observed for the other probe sizes as well. When the cranial and caudal areas were compared, the cranial area showed superior performance in discerning the WB severity. The study demonstrated that CF measurements made at a minimum of 10 locations could potentially offer an effective means of accurately distinguishing between the severity levels of WB myopathy and the affected areas.