The effect of electrical parameters (intensity and voltage) to obtain an effective water-bath stunning in a commercial poultry slaughterhouse was studied. A total of 390 broilers were randomly divided into six experimental groups according to the intensity (150 and 200 mA) and voltage (51-60, 61-80 and 81-100 V). Statistical analysis showed a significant (p<0.001) effect of electrical parameters on the cloacal reflex since the response rate was 8 s for 96% of broilers. On the other hand, the stunning treatments suppressed the palpebral reflex up to 12 s in 80% of broilers. All stun-treated broilers showed breathing response after 27 s with an average time between 45 and 50 s depending on voltage and intensity of the current. Regarding voltage, the percentage of complete neck cutting increased with the increase of voltage, presenting the highest levels in broilers stunned at 81-100 V (100 and 92.8%, for 150 and 200 mA, respectively). Concerning to intensity, the best results were obtained in broilers stunned at 150 mA, showing mean percentages of 94.83 and 87.30%, for 150 and 200 mA, respectively. The bruises on wings were significantly (p<0.001) affected by voltage, observing the highest values in broilers slaughtered at lower voltages. An opposite trend was observed on bruises under the wings since the lowest voltages showed (p<0.001) lower levels (1.34 and 1.42%, for 150 and 200 mA, respectively). Finally, bruises on dorsal winds and on back were significantly (p<0.001) influenced by intensity level, showing the lowest percentages in broilers stunned at 150 mA.

A multivariable linear model was used to analyse the incidence of carcass quality defects over one year in a commercial database that included 1,856 flocks of Ross broilers (9,188 shipments, 1,975,420 carcasses inspected). The incidence of foot-pad dermatitis (FPD), scratches and wing and back haematomas was scored and analysed in terms of the effects of transport distance, arrival time to the slaughterhouse, waiting time at the slaughterhouse, maximum outside temperature on the day of transport, feed conversion rate, stocking density, bird type (yellow-skinned females or males, white-skinned females or males and roaster females), thinning (birds transported after thinning, birds remaining after thinning, and non-thinned flocks), bed litter type (rice hulls, chopped straw or wood shavings), and ventilation system (dynamic, static or tunnel). The incidence of FPD was significantly (p<0.001) lower at higher maximum temperatures and higher in flocks with a higher feed conversion rate. FPD also increased with stocking density (kg/m2) and was, on average, 5.0% higher in males than females. Regarding thinning, FPD was 13% lower in birds transported after thinning. Birds raised on chopped straw had more FPD (49.3%), followed by wood shavings (31.1%). Scratches were higher at higher temperatures and increased with transport distance. Birds transported after thinning had 5.8% more scratches than non-thinned birds, while increased stocking density (kg/m2) on the farm tended to increase scratches. Back haematomas were 32.6% higher in birds that were thinned, while wing haematomas increased with stocking density (kg/m2). Back haematomas were also 23.7% higher in males and more common in white-skinned birds.

Breast anomalies in broilers, especially wooden breast (WB) and spaghetti meat (SM), cause high economic losses to the poultry meat sector. In order to identify the parameters that have a causal effect and to reduce the incidence of these myopathies, 141,792 broilers were analyzed in a total of 1477 batches using a visual grading system. The relationship among productive parameters such as the feed conversion ratio, live weight, growth rate, and mortality, was evaluated. Effects due to skin color (white vs. yellow), broiler sex (male, female, and mixed groups), feed presentation (grain vs. mash), and veterinary treatments (treated vs. untreated) were also included in the statistical study. Live weight was observed to have a significant effect (p < 0.001) on WB incidence, which increased by 1.11 for each 100 g of weight. Weight did not significantly affect the incidence of SM. Males had a higher incidence of WB and a lower incidence of SM than females. The incidence of both myopathies varied between samples that turned out to be significantly affected by some of the variables considered in the model, such as grain feeding and the feed conversion ratio. Controlling these factors in the broiler production could help to reduce the incidence of WB and SM.