Effect of pre-slaughter transport plant on blood constituents and meat quality in halothane genotype of NN Large White × Landrace pigs

A 3 × 3 factorial experiment has been conducted to study the effects of different transport time (Short: 40 min vs. Medium: 3 h vs. Long: 5 h) and stocking densities (Low: 5 pigs per pen or 230 kg/m2, Medium: 6 pigs per pen or 275 kg/m2 and High: 7 pigs per pen or 325 kg/m2) on some blood constituents and meat quality of four hundred and thirty two pigs including seventy two pigs that had been DNA tested (genotype: NN). The results are as follows: 1) Lactate dehydrogenase enzymatic activity increased as transport time increased, but it reached significance only for the high density group (P < 0.05). Lactate concentration was significantly lower in the group subjected to 3 h transport and low stocking density (P < 0.05). The concentration of cortisol was higher after 5 h transport than those transported for shorter time (40 min or 3 h; P < 0.05) and also significantly increased (P < 0.05) in the highest stocking density. The stocking density treatment had a difference tendency that ACTH concentration gradually increased as density enhanced. 2) Drip loss, pHu and Opto-staru were significantly affected by transport time in the longissimus thoracis muscle. Opto-staru was the only meat quality that was affected by transport time in the semimembranosus muscle, while the values of pH1, pHu, Opto-star1 and Opto-staru were lower (P < 0.05) in the low density group than medium or high density group. 3) The pigs from the 3 h transport group had significantly lower RBC, HGB and HCT (P < 0.05) compared with the short or long time transport groups. At the same time, pigs under the long time transport showed lower count of LYM than pig under 1 and 3 h transport conditions. Hence, from these data we conclude that the most adequate pre-slaughter transport time was 3 h for medium stocking density (less than 275 kg/m2) and at a warm environmental temperature in the Chinese commercial transport conditions.