Regmi P, Nelson N, Steibel J P, Anderson K E, Karcher D M
Department of Animal Sciences, Michigan State University, East Lansing, Michigan.
Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan.
Poult Sci. 2016 Oct 1;95(10):2225-34. doi: 10.3382/ps/pew199. Epub 2016 Jul 18.
Susceptibility of caged layers to osteoporosis and cage layer fatigue has generated interest in newer housing systems that favor increased load-bearing activities. However, high incidences of fractures incurred during lay period have been reported in these newer systems. This study is aimed at determining the housing and strain effects on bone properties: dry weight, percentage ash content, cortical density (CBD), cortical thickness (CBT), and keel bone deformities. Tibia, femur, and keel from Hy-Line Brown (HB), Hy-Line Silver Brown (SB), and Barred Plymouth Rock (BR) hens housed in conventional cages (CC), cage-free (CF), and cage-free with range (outdoor access; R) were studied. At 78 wk, 60 hens from each strain and housing system combination were euthanized and bones were excised for analysis. Quantitative computed tomography (QCT) was used to measure CBD and CBT in each bone. Three-dimensional images of keels were generated from software using QCT scans to analyze the deformities. Tibiae CBT was greater (P < 0.01) in BR compared to other two strains. Between housing systems, CBT was greater (P < 0.05) for mid and distal tibia of R and CF compared to CC. Tibiae and femoral cortex were denser (P < 0.05) in BR compared to HB and SB. There was no effect of housing system for femur CBD, but CBD was greater (P < 0.05) for middle and distal tibia of birds housed in R compared to CC. CBD for keel bone was greater (P < 0.05) in CF and R birds compared to CC birds. The housing system did not influence the dry bone weight and ash percentage of tibiae and femur. Each housing system was associated with high prevalence (>90%) of keel deformities and the housing and genotype influenced the type of deformity. These findings indicate that range and cage-free housing may have beneficial impact on tibia and keel bone integrity compared to conventional cages but the improvement may not be sufficient to prevent fractures or deformities of keel.
笼养蛋鸡对骨质疏松症和笼养蛋鸡疲劳的易感性引发了人们对更有利于增加承重活动的新型饲养系统的兴趣。然而，在这些新型系统中，产蛋期骨折的发生率很高。本研究旨在确定饲养方式和应变对骨骼特性的影响：干重、灰分含量百分比、皮质密度（CBD）、皮质厚度（CBT）和龙骨骨畸形。研究了饲养在传统鸡笼（CC）、无笼（CF）和有户外活动区域的无笼鸡舍（R）中的海兰褐（HB）、海兰银褐（SB）和横斑洛克（BR）母鸡的胫骨、股骨和龙骨。在78周龄时，对来自每个品系和饲养系统组合的60只母鸡实施安乐死，并切除骨骼进行分析。使用定量计算机断层扫描（QCT）测量每根骨骼的CBD和CBT。利用QCT扫描软件生成龙骨的三维图像，以分析畸形情况。与其他两个品系相比，BR的胫骨CBT更大（P<0.01）。在不同饲养系统之间，R和CF的胫骨中部和远端的CBT比CC更大（P<0.05）。与HB和SB相比，BR的胫骨和股骨皮质更致密（P<0.05）。饲养系统对股骨CBD没有影响，但与CC相比，R组鸡的胫骨中部和远端的CBD更大（P<0.05）。与CC组鸡相比，CF组和R组鸡的龙骨骨CBD更大（P<0.05）。饲养系统不影响胫骨和股骨的干骨重量和灰分百分比。每个饲养系统都与高比例（>90%）的龙骨畸形相关，饲养方式和基因型会影响畸形类型。这些发现表明，与传统鸡笼相比，户外活动区域和无笼饲养可能对胫骨和龙骨的完整性有有益影响，但这种改善可能不足以预防龙骨骨折或畸形。
