Bone fragility in egg laying hens

产蛋鸡的骨骼脆弱

• 批准号: RGPIN-2019-05374
• 负责人: Willie, Bettina
• 金额: $ 2.91万
• 依托单位: McGill University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=687571
• 关键词: Bone; fragility; egg; laying; hens

Bone is a common and ubiquitous tissue that forms the skeletons of most vertebrates, however nearly all of what is known concerning bone adaptation and fragility has been gleaned from studies in mammals. The egg laying hen is the most efficient calcium transporter among all vertebrates, transferring approximately 10% of its total body calcium volume daily to produce an egg shell, of which only half is estimated to originate from dietary sources. Estimates suggest that 20-35% of mortalities occurring in commercially caged egg-laying hens are caused by underlying disuse osteoporosis. Of concern is the prevalence of keel bone fractures that are reported to occur in 5.5% of hens at the onset of lay and affect up to 97% of hens by the end of lay. Canada has recently implemented a ban on new conventional cage construction and a 20-year phase-in period of alternative housing. Little is known about the effect of alternative housing on bone mass, structure and especially tissue level material properties in different strains chickens. Interestingly, studies have shown that hens in free run floor-housed or aviary systems have stronger bones, but a higher number of old healed fractures (occur prior to depopulation) compared to hens housed in conventional cages. The etiology of these fractures remains unclear, although some speculate that they are due to increased collisions. It remains unclear how bone adaptation to mechanical stimuli provided by different housing contributes to fracture risk. ***In this research program, I will examined hens housed in three commonly used commercially available systems which provide varying levels of mechanical stimuli. I will examine mechanical strains engendered in keel bones during various activities in two strains of hens (Lohmann Brown and Lohmann Select Leghorn-Lite) throughout the lay period (18, 32 and 54 weeks of age). I will also examine fractured and nonfractured keel bone mass, microstructure, and quality in hens to determine if outcome measures are altered in fractured bones. To determine if bone quality during fracture is also deteriorated at remote sites I will also perform these analyses in a long bone (tibiotarsus) of adult hens with and without keel bone fractures. The short-term goal of this NSERC DG is to elucidate the etiology of keel bone fractures in hens. The long-term goal of my program is to use bioengineering approaches to understand skeletal health of birds. This program will allow us to study in a highly-controlled animal model and environment, the detailed interactions between the two fundamental processes that play critical roles in bone regulation and adaptation mechanical stimulation and mineral homeostasis. This research program is poised to provide Canadian poultry farmers information concerning the etiology of keel bone fractures and how housing environments may contribute to fracture risk, as they seek to adhere to new housing guidelines.**

骨骼是构成大多数脊椎动物骨骼的一种常见且无处不在的组织，然而，几乎所有关于骨骼适应和脆弱性的已知信息都是从哺乳动物的研究中收集到的。在所有脊椎动物中，蛋鸡是最有效的钙转运体，每天将其全身钙体积的10%左右转移到蛋壳中，其中只有一半估计来自饮食来源。据估计，在商业笼养的蛋鸡中，20-35%的死亡是由潜在的废用性骨质疏松症引起的。值得关注的是龙骨骨折的患病率，据报道，5.5%的母鸡在产蛋开始时发生骨折，到产蛋结束时影响的母鸡高达97%。加拿大最近实施了一项禁令，禁止新的传统笼式建筑和20年的替代住房逐步淘汰期。不同鸡舍对不同品系鸡骨量、结构尤其是组织水平材料性能的影响尚不清楚。有趣的是，研究表明，与饲养在传统笼子里的母鸡相比，自由饲养的地板饲养或鸟舍系统中的母鸡骨骼更强壮，但旧愈合骨折（发生在种群减少之前）的数量更高。这些骨折的病因尚不清楚，尽管一些人推测是由于碰撞增加所致。目前尚不清楚骨骼对不同外壳提供的机械刺激的适应如何导致骨折风险。***在这个研究项目中，我将研究饲养在三种常用的商业系统中的母鸡，这些系统提供不同程度的机械刺激。我将在整个产蛋期（18、32和54周龄）对两种母鸡（Lohmann Brown和Lohmann Select leghhorn - lite）的各种活动中产生的龙骨机械应变进行研究。我还将检查母鸡骨折和非骨折的龙骨质量、微观结构和质量，以确定骨折后的结果是否会改变。为了确定骨折时骨质量是否也会在远处部位恶化，我还将对有和没有龙骨骨折的成年母鸡的长骨（胫跗骨）进行这些分析。这个NSERC DG的短期目标是阐明母鸡龙骨骨折的病因。我的项目的长期目标是用生物工程的方法来了解鸟类的骨骼健康。这个项目将允许我们在一个高度控制的动物模型和环境中，研究在骨调节和适应中起关键作用的两个基本过程之间的详细相互作用机械刺激和矿物质稳态。这项研究计划旨在为加拿大家禽养殖户提供有关龙骨骨折的病因和住房环境如何可能导致骨折风险的信息，因为他们寻求遵守新的住房指南