Observational studies describing the impact of transport duration on weaned piglet welfare are limited. Current Canadian transport regulations are heavily informed by studies involving market hogs. Due to physiological differences between weaned piglets and market hogs, additional data on their response to transport are needed for age-specific evidence-based recommendations. A cohort study was conducted to describe and compare mortality, injury, weight change, hematological or biochemical changes in hydration, muscle injury and stress response observed in weaned piglets undergoing short duration (SD, <3 h), or long duration (LD, >30 h) commercial summertime transport events. Data collection on 440 of 11,434 transported piglets occurred the morning of the day before transport (T0), at arrival (T1) and approximately 3 to 4 d (78 to 93 h) after arrival at the nursery barn (T2). Low mortality occurred over all transport events (0.06%) with no association observed between transport duration and odds of death during transport (P = 0.62). The incidence of lameness between T0 and T1 was low (1.84% of the 435 focal piglets scored) with all lameness cases identified as mild in severity. Lesions on ears and skin were more prevalent than other injury types after transport (T1) and may have been related to mixing aggression associated with weaning rather than transport alone. LD piglets weighed 0.39 kg less than SD piglets at T1 (P < 0.01), but no difference in group weight was observed at T2 (P = 0.17). Hematological and biochemical differences were present between groups at T1. LD piglets had increased hematocrit levels compared with SD piglets (P = 0.01), suggesting increased body water losses. SD piglets showed greater levels of muscle injury compared with LD piglets including elevated aspartate aminotransferase (P < 0.01) and creatine kinase (P < 0.01). However, these parameters were within normal reference ranges for piglets of this age group. Indicators of physiological stress response including cortisol and neutrophil to lymphocyte ratios were elevated in SD piglets compared with LD piglets (P = 0.02 and P < 0.01, respectively). The results of this study demonstrate that both short and long transport durations can result in detectable physiological changes in weaned piglets. The overall impact of these durations on piglet welfare should be further explored by analyzing behavioral time budgets during and after transport.

中文翻译：

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在加拿大商业环境中观察到的断奶仔猪对两个运输时间的生理反应

描述运输时间对断奶仔猪福利影响的观察性研究是有限的。当前的加拿大运输法规很大程度上来自涉及市场生猪的研究。由于断奶仔猪和商品猪之间的生理差异，需要更多关于它们对运输反应的数据来制定针对特定年龄的循证建议。进行了一项队列研究，以描述和比较在短期（SD，<3 小时）或长期（LD， >30 h) 商业夏季运输活动。对 11,434 头运输仔猪中的 440 头的数据收集发生在运输前一天的早晨（T0），到达时（T1）和到达保育舍后（T2）大约 3 到 4 天（78 到 93 小时）。所有运输事件的死亡率都较低（0.06%），运输持续时间和运输过程中的死亡几率之间没有观察到相关性（P = 0.62）。T0 和 T1 之间跛行的发生率很低（435 头病灶仔猪评分的 1.84%），所有跛行病例的严重程度都被确定为轻度。运输后（T1）耳朵和皮肤上的损伤比其他损伤类型更普遍，并且可能与脱机相关的混合攻击有关，而不是单独运输。LD 仔猪在 T1 时比 SD 仔猪重 0.39 kg (P < 0.01)，但在 T2 时未观察到组体重差异 (P = 0.17)。在 T1 时，各组之间存在血液学和生化差异。与 SD 仔猪相比，LD 仔猪的红细胞比容水平增加（P = 0.01），表明体内水分流失增加。与 LD 仔猪相比，SD 仔猪表现出更高水平的肌肉损伤，包括升高的天冬氨酸氨基转移酶 (P < 0.01) 和肌酸激酶 (P < 0.01)。然而，这些参数在这个年龄组的仔猪的正常参考范围内。与 LD 仔猪相比，SD 仔猪的生理应激反应指标（包括皮质醇和中性粒细胞与淋巴细胞的比率）升高（分别为 P = 0.02 和 P < 0.01）。这项研究的结果表明，短途和长途运输持续时间都可以导致断奶仔猪的生理变化。