Nutritional means to enhance skeletal development in pullets and subsequent effects on layers productivity, bone health and welfare

加拿大的供应管理鸡蛋生产系统有1,021个注册鸡蛋农场，总产量约为2000万只，为加拿大的国内生产总值贡献了12.8亿美元。骨骼健康表现为骨质疏松症是不同饲养制度下蛋鸡的一个持续问题，对鸡群的生产力和蛋壳质量产生不利影响，从而影响盈利能力。骨质量受遗传、住房制度、环境和营养的影响。然而，性成熟度降低而不同时改善饲料中的矿物质含量的趋势可能与母鸡用更少的饲料生产更多蛋的能力增加（更多的钙输出和更少的输入）并列，使得骨矿化在饲养和/或产蛋周期中受损，从而引起由代谢性钙不足和骨质疏松症引起的死亡和发病。改善蛋鸡骨骼健康的研究往往集中在产蛋期间的环境和营养调控上。然而，在12周龄时，小母鸡发育成一个成熟的框架大小，随后在性成熟前后形成髓骨，在活动期补充钙可能太晚而不能改善骨密度和质量。我们的假设是，适当的骨骼发育对于高水平的产蛋量和现代蛋鸡替代性住房的挑战至关重要。本研究旨在探讨饲料结构（纤维含量和石灰石颗粒大小的控制）和最佳钙、磷和维生素D补充对雏鸡骨骼发育的作用以及对母鸡生产力、蛋壳质量、存活率和福利的后续影响。这是一个及时的研究，并将提供有价值的信息，以鸡蛋行业在即将到来的变化，在加拿大母鸡住房系统。该项目将采用各种实验、统计和分析技术，从而为培养高素质的人才提供极好的机会。具体而言，该研究项目将支持1名博士，2名硕士论文，1名硕士课程，2名本科生和1名博士后研究员以及一名技术人员的培训。

Canadian supply managed egg production system has 1,021 registered egg farms with a total of approximately20 million layers and contributes $1.28B to Canada's GDP. Bone health manifested as osteoporosis is apersistent problem in layers under different housing systems with detrimental effects on flock productivity andegg shell quality and thus profitability. Bone quality is influenced by genetics, housing system environment andnutrition. However, the trends of decreased sexual maturity without concurrent refinement in mineral contentof the feed may juxtapose with the hen's increased capacity to produce more eggs with less feed (more calciumoutput and less input) such that bone mineralization is impaired during rearing and /or lay cycle giving rise tomortality and morbidity stemming from metabolic calcium insufficiency and osteoporosis. Studies to improvehen skeletal health often focus on manipulating environment and nutrition during the laying. However, aspullets develop a mature frame size by 12 weeks of age followed by formation of medullary bone aroundsexual maturation, supplementing calcium during active lay may be too late to improve bone density andquality. Our hypothesis is that proper skeletal development is essential for high levels egg production andchallenges of alternative housing for modern layers. Studies will be conducted to investigate the role of feedstructure (manipulation of fiber fraction and limestone particle size) and optimal calcium, phosphorous andvitamin D supplementation on skeletal development pullets and subsequent effects in productivity, egg shellquality, livability and welfare in hens. This is a timely research and will provide valuable information to theegg industry in light of the forthcoming changes in Canadian hen housing systems. The project will employ avariety of experimental, statistical, and analytical techniques thus providing excellent opportunities for thetraining of highly qualified personnel. Specifically, the research project will support training of 1 PhD, 2 MScby thesis, 1 MSc by coursework, 2 undergraduate students and 1 Postdoctoral Fellow as well as a technician.