Sørensen P, Su G, Kestin S C
Department of Animal Breeding and Genetics, Danish Institute of Agricultural Sciences, Tjele.
Poult Sci. 2000 Jun;79(6):864-70. doi: 10.1093/ps/79.6.864.
The effects of stocking density (STD) on leg weakness in broiler chickens was assessed in two trials. The interaction between age and STD on leg weakness was further evaluated in one trial. In Trial 1, walking ability was assessed at 28, 42, and 49 d of age. Birds were stocked at 833, 625, or 435 cm2 per bird. In Trial 2, birds were stocked at 625 or 455 cm2 per bird and assessed for tibial dyschondroplasia (TD) by radiographic examination at 28 d and walking ability at 35 d. Foot pad burn, hock burn, and angulation of the hock joint were also assessed at slaughter on Day 42. Body weight was measured during both trials. At 4 wk of age, leg weakness was a relatively minor problem; few severely lame birds had a gait score (GS) of 4 or 5 at any density. However, 2 wk later, the birds had substantially poorer walking ability. Further deterioration had occurred by 7 wk of age. At all ages, males exhibited greater leg weakness than did females, and the proportion of severely lame birds increased with age of assessment. The effect of STD was consistent across both trials; higher STD were associated with poorer walking ability and reduced live weights. In Trial 2, higher STD resulted in more foot and hock burns. Females were more sensitive to STD than were males However, there was no effect of STD on the prevalence of TD or angulation of the hock joint. The effect of high STD on walking ability was apparent even at 4 wk of age. Adjusting the observations for differences in BW did not alter the findings. It was concluded that the lower STD substantially reduced the prevalence of leg weakness.
在两项试验中评估了饲养密度（STD）对肉鸡腿部无力的影响。在一项试验中进一步评估了年龄与STD对腿部无力的交互作用。在试验1中，在28、42和49日龄时评估行走能力。每只鸡的饲养面积分别为833、625或435平方厘米。在试验2中，每只鸡的饲养面积为625或455平方厘米，并在28日龄时通过X光检查评估胫骨软骨发育不良（TD），在35日龄时评估行走能力。在42日龄屠宰时还评估了脚垫烧伤、跗关节烧伤和跗关节角度。在两项试验中均测量了体重。在4周龄时，腿部无力是一个相对较小的问题；在任何密度下，很少有严重跛行的鸡步态评分为4或5。然而，2周后，鸡的行走能力明显变差。到7周龄时进一步恶化。在所有年龄段，雄性比雌性表现出更强的腿部无力，并且严重跛行鸡的比例随着评估年龄的增加而增加。STD的影响在两项试验中是一致的；较高的STD与较差的行走能力和体重减轻有关。在试验2中，较高的STD导致更多的脚垫和跗关节烧伤。雌性比雄性对STD更敏感。然而，STD对TD的患病率或跗关节角度没有影响。即使在4周龄时，高STD对行走能力的影响也很明显。对体重差异进行观察调整并没有改变研究结果。得出的结论是，较低的STD显著降低了腿部无力的患病率。
