Comparative analysis of the morphology, chemistry and structure of the tibiotarsus, humerus and keel bones in laying hens

ABSTRACT

1. Bone properties are adapted to their specific functions in the animal, so various types of bones develop different characteristics depending on their location in the skeleton.

2. The aim of this research was to compare the chemical composition, mineral characteristics and structural organisation in tibiotarsus, humerus and keel bones as representatives of hen skeletal mineralisation. Complementary analytical techniques, such as X-ray radiography, optical and electron microscopy, thermogravimetry and 2D X-ray diffraction, were used for characterisation.

3. The humerus had a thinner cortex and cortical bone mineral had higher crystallinity and a greater degree of crystal orientation than the tibiotarsus. The humerus generally lacks medullary bone although, when present, it has a higher mineral content than seen in the tibiotarsus. These differences were attributed to the different forces that stimulate bone formation and remodelling.

4. The keel cortical bone had a lower degree of mineralisation than the tibiotarsus or humerus. Its degree of mineralisation decreased from the cranial to the distal end of the bone. This gradient may affect keel mechanical properties, making it more prone to deformation and fractures.

5. Data from studying different bones in laying hens can help to understand mineralisation as well as finding solutions to prevent osteoporosis-related fractures.

KEYWORDS:

• Tibiotarsus
• humerus
• keel
• bone
• laying hens
• morphology
• biochemistry
• structure

Acknowledgments

We are grateful for financial support through grants CGL2015-64683-P (Ministerio de Ciencia e Innovación, Spain), RNM-179 group (Junta de Andalucía, Spain) and ERANET ANIHWA grant ‘BetterBones’. We thank Jose Romero, Rocio Marquez (U. Granada) for their help during sample preparation and analyses.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the ERANET ANIHWA grant ‘BetterBones’ [291815]; COST Action Keel Bone Damage [CA15224]; Ministerio de Ciencia e Innovación, Spain [CGL2015-64683-P].