Water sprinkling market pigs in a stationary trailer. 2. Effects on selected exsanguination blood parameters and carcass and meat quality variation

In each of 12 weeks between May and September, 2011, two identical pot-belly trailers were loaded with 208 pigs each and transported to the slaughter plant (2 h trip). One of the two trailers was equipped with a water sprinkling system (WS) installed inside the truck compartments whereas the other one transported pigs under standard commercial conditions (control, CONT). The water sprinkling system was activated for 5 min in the stationary truck, both at the farm (at the end of loading) and at the plant (immediately before unloading). Blood lactate levels at exsanguination, carcass and meat quality traits were assessed on a sub-sample of randomly selected pigs (n=384/576). Exsanguination lactate levels were lower (P=0.02) in WS pigs compared to CONT, regardless of ambient temperature. Concurrently, the pH value of the Longissimus dorsi (LD) muscle at 1 h post-mortem (pH1) was greater (P=0.009) in WS pigs compared to CONT, regardless of ambient temperature. The effect of water sprinkling interacted with location inside the truck and ambient temperature. Water sprinkling reduced exsanguination lactate levels in pigs transported in compartments 5 and 8 (which are located at the front and at the rear of the middle deck, respectively) such that lower lactate was observed in compartment 5 at 15 degrees C (P=0.03) and 18 degrees C (P=0.009), and in compartment 8 at 22 degrees C (P=0.03) and 25 degrees C (P=0.04). In compartment 5, the pH1 value in the LD muscle of WS pigs was higher than in the CONT group at 18 degrees C (P=0.002), 22 degrees C (P<0.001) and 25 degrees C (P=0.005); pH1 in the SM muscle of WS pigs was lower at 18 degrees C (P=0.01) and 22 degrees C (P=0.02); and drip loss in the WS group was lower than in the CONT group at 22 degrees C (P=0.01), and at 25 degrees C (P=0.02). No significant effect was detected in compartment 4 (which is located at the rear of the top floor), or in compartment 9 (which is located at the front to the bottom deck). The results of this study showed that the sprinkling protocol applied was effective, particularly in some trailer compartments, in reducing stress response and improving pork quality of pigs transported in pot-bellied trailers. (C) 2013 Elsevier B.V. All rights reserved.