Effects of different moving devices at loading on stress response and meat quality in pigs

Abstract

Although there is increasing evidence regarding the negative welfare and meat quality implications of electric prod use for slaughter-weight pigs, this handling tool continues to be used. Therefore, the behavioral and physiological response and carcass and meat quality of 360 pigs being loaded onto a truck for transportation to slaughter according to 3 handling procedures were studied. The 3 handling procedures were 1) moving with an electric prod and board from the finishing pen to the truck (EP); 2) moving with a board and a paddle from the finishing pen to the truck (PAD); 3) moving with a board and a paddle from the finishing pen and using a compressed air prod in the ramp before going into the truck (CAP). A subpopulation of 144 pigs (48 pigs/treatment) was equipped with heart rate monitors. Blood samples were collected from the same animals at exsanguination for the analysis of creatine phosphokinase and lactate. Data were analyzed using an ANOVA for factorial design, with the animal as the experimental unit. Behavior was analyzed with MIXED model procedure with treatment as a fixed effect. During loading, EP pigs slipped and fell (P < 0.001) and overlapped (P = 0.03) more often, but stopped (P < 0.001) and attempted turns (P = 0.01) less often than CAP or PAD. With CAP, pigs made more 180° turns (P = 0.01) than with PAD or EP. Loading with EP led to more and longer vocalizations (P = 0.02 and P = 0.001, respectively) than loading with CAP or PAD. Loading took longest with CAP and was quickest with EP (P = 0.01). Pigs handled with EP had a greater heart rate than those moved with PAD and CAP at loading (P < 0.001), wait at loading (P < 0.001), at unloading (P = 0.05), and in lairage (P = 0.02). Pigs loaded with EP had greater (P = 0.05) lactate concentrations in blood at exsanguination compared with pigs handled with CAP, with pigs loaded with PAD being intermediate. Furthermore, ultimate pH values in the semimembranosus and adductor muscles of EP pigs were greater (P = 0.002 and P = 0.004, respectively) compared with those from PAD and CAP pigs. Greater (P = 0.04) incidence of blood-splashed hams was found in EP pigs compared with PAD and CAP pigs. Therefore, considering animal welfare, carcass bruising, and blood splashes standpoints, EP should be replaced with PAD or CAP. However, additional research is necessary to identify methods that improve the loading efficiencies of PAD and CAP without adversely affecting animal welfare parameters.