This study aimed to evaluate the effects of different stunning frequencies and electrical current waveforms on chicken welfare and meat quality. Two-hundred-thirty-two Cobb broilers, 48 d of age and 2.76 ± 0.47 live-weight, were randomly assigned into 4 stunning treatments - 2 frequencies (300 Hz and 650 Hz) and 2 current waveforms (direct current [DC] and alternating current [AC]). Broilers were electrically stunned in a water bath in a commercial slaughterhouse (70 V, 100 mA). The electronarcosis and stunning efficiency were confirmed by assessment of visual parameters (absence of rhythmic breathing, ocular reflex, and coordinated wing flapping) and blood parameters (lactate, glucose, creatine kinase, sodium, and potassium), which were measured after bleeding. The incidence of traumas and injuries was assessed after plucking. Meat quality analysis was performed in Pectoralis major (PM), with determinations of pH, breast yield (PMY), water holding capacity (WHC), water absorption capacity (WAC), thawing loss (DL), cooking loss (CL), shear force (SF), and instrumental color (a*, b*, L*, C*, and h). The interaction between waveform and frequency was significant (P < 0.05) only for lactate, sodium, and lightness (L*). Lactate and sodium levels decreased at 300 Hz-DC. Meat lightness increased at 300 Hz-DC. The individual effect of frequency was significant for glucose, creatine kinase, potassium, WHC, PMY, b*, C*, and h. Regarding waveform, AC decreased plasma glucose and DC decreased creatine kinase and WAC. In general, stunning frequency exerts greater influence than waveform on the welfare and meat quality parameters of broilers. The use of frequency at 650 Hz proved to render animals efficiently unconscious and to promote greater meat quality.
Introduction: Deltamethrin (DM) is a synthetic pyrethroid toxic to vertebrates and lethal to fish at concentrations one million times lower than to mammals. It can be easily absorbed by the gills even when at low concentrations in the water, which contributes to the increased fish sensitivity. Objective: Determine the lethal and sub-lethal concentrations of DM to Jundiá (Rhamdia quelen) during 96 hours of exposure. Materials and methods: The study used 108 Jundiá fish with an average weight of 40 ± 5 g. The experiment was executed in triplicate and each set of fish was submitted to one of the following conditions: control (0 mg.L-1) and eight concentrations of DM (0.1; 0.5; 1.0; 1.5; 1.7; 2.0; 2.3; 5.0 mg.L-1). Results: Themain toxic signs observed were alterations in the respiratory, nervous and integumentary systems. The sub-lethal concentration at 96 hours was between 1.0 and 1.5 mg.L-1 and the lethal concentration was 1.7 mg.L-1. Conclusion: DM shows toxicity to Jundiá when present at ≥ 1.0 mg.L-1 in water.
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