本文研究了电击晕、CO2致晕和不同在轨时间（32、38、44 min）对杜大长三元杂交猪血液应激指标、预冷损耗以及猪肉品质的影响。结果显示：与电击晕相比，CO2致晕使生猪血液中乳酸含量、皮质醇含量、肌酸激酶含量和乳酸脱氢酶含量分别显著（p＜0.05）降低了85.50 mg/dL、161.62 ng/mL、2828.36 U/L、192.71 U/L，断骨率降低了2.82 %。在CO2致晕条件下，在轨时间由32 min延长至44 min时，腔体温度（喷淋后）和预冷损耗分别降低了1.72 ℃和0.28%，且预冷损耗达到最小（0.89%）。另外，在所有处理中，采用CO2致晕且在轨时间为44 min的工艺条件时，红度值a*最大（7.55）且嫩度较高，滴水损失（3.22%）、蒸煮损失（29.90%）、疑似PSE肉发生率（19.13%）及PSE肉发生率（9.10%）均为最低，从而改善了猪肉品质。因此，在实际生产中采用CO2致晕并适度延长在轨时间，可以减小应激反应、降低预冷损耗、改善猪肉品质。

Influences of electrical stunning, CO2 stunning and different durations in orbit (32, 38 and 44 min) on blood stress indicators, pre-cooling loss and pork quality of Dudachang crossbred pig were studied in the paper. The results showed that lactic acid content, cortisol content, creatine kinase content and lactate dehydrogenase content in CO2 stunning pig blood were lowered significantly by 85.50 mg/dL, 161.62 ng/mL, 2828.36 U/L and 192.71 U/L (p＜0.05), respectively, compared with that by electrical stunning. The bone breakage rate was lowered by 2.82%. Body chamber temperature (after being sprayed) and pre-cooling loss were reduced by 1.72 ℃ and 0.28 %, respectively when duration in orbit was prolonged from 32 min to 44 min under CO2 stunning condition, and the pre-cooling losses reached the minimum level (0.89%). In addition, the redness value a* was the maximum (7.55), with higher tenderness, while drip loss (3.22%), cooking loss (29.90%), suspected incidence of PSE meat (19.13%) and the incidence of PSE meat (9.10%) were the lowest in all treatments, when CO2 stunning was adopted under the orbit duration process conditions for 44 min. Therefore, CO2 stunning with proper orbit duration prolongation in practical production could reduce stress reaction, lower pre-cooling loss and improve pork quality.

公益性行业（农业）科研专项（201303083）