Etterlin Pernille Engelsen, Morrison David A, Österberg Julia, Ytrehus Bjørnar, Heldmer Eva, Ekman Stina
Section of Pathology, Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences (SLU), 750 07, Uppsala, Sweden.
Systematic Biology, EBC, Uppsala University, 752 36, Uppsala, Sweden.
Acta Vet Scand. 2015 Sep 29;57:63. doi: 10.1186/s13028-015-0154-7.
Organic pig production is expanding and amongst the objectives of organic farming are enhancing animal health and welfare. However, some studies have reported a higher prevalence of lameness and joint condemnation at slaughter in free-range/organic pigs than in conventionally raised pigs. Organic slaughter pigs have free-range housing in which indoor and outdoor access is compulsory, while in conventional farming the pigs are commonly confined to indoor pens. The present study evaluated the effects of free-range and confined housing on lameness prevalence in a herd of 106 finisher pigs, and whether osteochondrosis and Erysipelothrix rhusiopathiae associated arthritis influences these effects. We also evaluated the association between clinical lameness during the rearing period and joint condemnations at slaughter.
Seventy free-range and 36 confined housed fattener pigs were scored for their gait twice during the rearing period and 848 joints were evaluated post mortem. Osteochondrosis was more frequent among free-range than confined pigs (P < 0.05), and when present it was also more severe (P < 0.001). Pigs with more numerous and more severe osteochondral lesions had their gait affected more than did pigs with fewer such lesions (P < 0.05). Hence it was a paradox that we did not detect more lameness among the free-range pigs than the confined pigs. E. rhusiopathiae associated arthritis was not diagnosed. The association between gait remarks/clinical lameness and joint condemnations at slaughter was not significant.
The results indicate that free-range housing may have both positive and negative effects on locomotory traits. Free-range pigs may be less clinically affected by osteochondrosis than are confined pigs. One explanation for this effect may be strengthening of joint supportive tissue and pain relief promoted by exercise. Visual gait scoring missed serious joint lesions that probably were harmful to the pigs, and should therefore not be used as a sole indicator of joint/leg health in welfare inspection of pigs. The association between gait scores and joint condemnation appeared to be poor. This study was limited to one herd, and so more and larger studies on the effects of free-range housing on lameness severity and osteochondrosis development in pigs are recommended.
有机猪养殖正在扩大，有机养殖的目标之一是提高动物健康和福利。然而，一些研究报告称，与传统养殖的猪相比，散养/有机猪的跛行患病率和屠宰时关节废弃率更高。有机屠宰猪采用散养方式，必须有室内和室外活动空间，而在传统养殖中，猪通常被限制在室内猪栏。本研究评估了散养和圈养对106头育肥猪群跛行患病率的影响，以及骨软骨病和猪丹毒杆菌相关关节炎是否会影响这些结果。我们还评估了育肥期临床跛行与屠宰时关节废弃之间的关联。
在育肥期对70头散养猪和36头圈养猪的步态进行了两次评分，并在死后对848个关节进行了评估。散养猪的骨软骨病比圈养猪更常见（P < 0.05），而且一旦出现，病情也更严重（P < 0.001）。骨软骨病变数量更多、更严重的猪，其步态受影响程度比病变较少的猪更大（P < 0.05）。因此，一个矛盾的现象是，我们并未发现散养猪的跛行情况比圈养猪更多。未诊断出猪丹毒杆菌相关关节炎。步态评分/临床跛行与屠宰时关节废弃之间的关联不显著。
结果表明，散养可能对运动性状有积极和消极两方面的影响。散养猪在临床上受骨软骨病的影响可能比圈养猪小。这种影响的一种解释可能是运动促进了关节支持组织的强化和疼痛缓解。视觉步态评分遗漏了可能对猪有害的严重关节病变，因此在猪的福利检查中，不应将其作为关节/腿部健康的唯一指标。步态评分与关节废弃之间的关联似乎较弱。本研究仅限于一个猪群，因此建议开展更多、规模更大的研究，以探讨散养对猪跛行严重程度和骨软骨病发展的影响。
