Norring M, Valros A, Valaja J, Sihvo H-K, Immonen K, Puolanne E
1Research Centre for Animal Welfare, Department of Production Animal Medicine,University of Helsinki,Helsinki,Finland.
2Department of Agricultural Sciences,University of Helsinki,Helsinki,Finland.
Animal. 2019;13(8):1690-1695. doi: 10.1017/S1751731118003270. Epub 2018 Dec 17.
Wooden breast myopathy, a condition where broiler breast muscles show a hardened consistency post-mortem, has been described recently. However, it is not known how wooden breast myopathy affects the bird activity or welfare. Altogether, over 340 birds of five commonly used commercial hybrids were housed in 25 pens, and sample birds killed at ages of 22, 32, 36, 39 and 43 days. Their breast muscle condition was assessed post-mortem by palpation. The birds were gait scored and their latency to lie was measured before killing. For further behavior observations, one affected and healthy bird in 12 pens were followed on 5 days for 20 minutes using video recordings. The connection of myopathy to gait score and activity was analyzed with mixed models. A higher gait score of wooden-breast-affected birds than that of unaffected birds (2.9 ± 0.1 v. 2.6 ± 0.1, P < 0.05) indicated a higher level of locomotor difficulties over all age groups. The wooden-breast-affected birds had fewer crawling or movement bouts while lying down compared with unaffected (P < 0.05). Wooden breast myopathy-affected birds were heavier (2774 ± 91 v. 2620 ± 91 g; P < 0.05) and had higher breast muscle yield (21 ± 1 v. 19 ± 1%; P < 0.05) than unaffected birds overall. Older birds had longer lying bouts, longer total lying time, fewer walking bouts, more difficulties to walk and to stand compared with younger birds (P < 0.05). Birds with poorer gait had longer total lying time and fewer walking bouts (P < 0.05). Birds with greatest breast muscle yield had the largest number of lying bouts (P < 0.05). It was concluded that wooden breast myopathy was associated with an impairment of gait scores, and may thus be partly linked to the common walking abnormalities in broilers.
木胸肌病是一种肉鸡胸肌在死后呈现硬化质地的病症，最近已有相关描述。然而，尚不清楚木胸肌病如何影响禽类的活动或福利。总共将超过340只5种常用商业杂交品种的禽类饲养在25个鸡舍中，并在22、32、36、39和43日龄时宰杀样本禽类。通过触诊在死后评估它们的胸肌状况。在宰杀前对禽类进行步态评分并测量其躺卧潜伏期。为了进行进一步的行为观察，使用视频记录对12个鸡舍中的一只患病禽类和一只健康禽类连续5天、每天20分钟进行跟踪。使用混合模型分析肌病与步态评分和活动之间的关联。受木胸肌病影响的禽类的步态评分高于未受影响的禽类（2.9±0.1对2.6±0.1，P<0.05），这表明在所有年龄组中运动困难程度更高。与未受影响的禽类相比，受木胸肌病影响的禽类在躺卧时的爬行或运动次数更少（P<0.05）。总体而言，受木胸肌病影响的禽类比未受影响的禽类更重（2774±91对2620±91克；P<0.05），胸肌产量更高（21±1对19±1%；P<0.05）。与年轻禽类相比，年长禽类的躺卧时间更长、总躺卧时间更长、行走次数更少、行走和站立更困难（P<0.05）。步态较差的禽类总躺卧时间更长且行走次数更少（P<0.05）。胸肌产量最高的禽类躺卧次数最多（P<0.05）。研究得出结论，木胸肌病与步态评分受损有关，因此可能部分与肉鸡常见的行走异常有关。
