The objective of a study at The Hebrew University in Rehovot, Israel, was to examine the effect of embryonic nutritional enrichment on the development and properties of broiler leg bones (tibia and femur) from the prenatal period until maturity.

In a paper published in Journal of Animal Science, R. Yair and colleagues explain that, to accomplish the objective, 300 eggs were divided into two groups: a non-injected group (control) and a group injected in ovo with a solution containing minerals, vitamins and carbohydrates (enriched).

Tibia and femur from both legs were harvested from chicks on embryonic days 19 (E19) and 21 (E21) and days 3, 7, 14, 28 and 54 post-hatch (n=8). The bones were mechanically tested (stiffness, maximal load, and work to fracture) and scanned in a micro-computed tomography (μCT) scanner to examine the structural properties of the cortical [cortical area, medullary area, cortical thickness, and maximal moment of inertia (I-max)] and trabecular (bone volume percentage, trabecular thickness, and trabecular number) areas.

To examine bone mineralisation, bone mineral density (BMD) of the cortical area was obtained from the μCT scans and bones were analysed for the ash and mineral content.

The results showed improved mechanical properties of the enriched group between E19 and day 3 and on day 14 (P<0.05).

Differences in cortical morphology were noted between E19 and day 14 as the enriched group had greater medullary area on E19 (femur), reduced medullary area on E21 (both bones), greater femoral cortical area on day 3 and greater I-max of both bones on day 14 (P<0.05).

The major differences in bone trabecular architecture were that the enriched group had greater bone volume percentage and trabecular thickness in the tibia on day 7 and the femur on day 28 (P<0.05).

The pattern of mineralisation between E19 and day 54 showed improved mineralisation in the enriched group on E19 whereas on days 3 and 7, the control group showed a mineralisation advantage, and on days 28 and 54, the enriched group showed again greater mineralisation (P<0.05).

Yair and colleagues conclude their study demonstrates that in-ovo enrichment affects multiple bone properties pre- and post-natally and showed that avian embryos are a good model for studying the effect of embryonic nutrition on natal and post-natal development.

More importantly, they say, the enrichment led to improved mechanical properties until day 14 - roughly one-third of the lifespan of the bird - which confers a big advantage for the young broiler.

Additionally, the improved mineralisation and trabecular architecture on days 28 and 54 indicate a potential long-term effect of altering embryonic nutrition, the researchers remarked.

Reference

^{Yair R., R. Shahar and Z. Uni. 2013. Prenatal nutritional manipulation by in ovo enrichment influences bone structure, composition, and mechanical properties. J. Anim. Sci. 91(6):2784-2793. doi: 10.2527/jas.2012-5548}

August 2013