Bone type matters in broiler bone ash

Matching leg bone type to bird age improves sensitivity of bone ash measures in poultry, new research has revealed.

A Nottingham Trent University study found that the best leg bone for differentiating response to diet alters with bird age.

Bone ash content accurately represents key mineral content – calcium and phosphorus – and has long been the poultry sector’s tool of choice for assessing skeletal mineralisation.

As the sector advances in its quest for precision agriculture, it is increasingly important to ensure the assessment tools used by poultry scientists remain sensitive enough to detect subtle alterations in dietary supply of nutrients.

Phosphorus is vital for the development and maintenance of the skeletal system in poultry, but represents a knife’s edge in nutrient supply: under-supply risks skeletal integrity issues for the birds and over-supply is economically and environmentally costly.

Phosphorus is supplied to poultry either as rock phosphate  – which is a finite global resource predicted to run out in 50-100 years – or by adding a digestive enzyme,phytase, to the diet to make plant phosphorus available to poultry.  

The global phytase market is estimated to be worth £300 million and to save the feed sector around £2 billion each year.

The economic and environmental interest in optimising efficiency of phosphorus use in poultry is immense so it is vital that bone mineralisation measures can identify even the smallest improvement in bone mineralisation resulting from a dietary change.

The findings from this latest study, published in the Journal of Applied Poultry Research, showed that using smaller bones such as the foot in early life and the larger femur bones near slaughter age dramatically increased the sensitivity of the bone ash method.

The team, from the university's School of Animal, Rural and Environmental Sciences, studied the effect of feeding broiler chicks diets with either standard or low phosphorus supply over five weeks from hatching. Each week, the toe, foot, tibia and femur bones from 12 birds were individually assessed for ash content.

The researchers found that while toe ash was the most time efficient bone to measure, it was only able to identify diet differences at week two post hatch, whereas the femur did not show any differences until week three but then continues to show differences between diets until week six.

Both foot and tibia ash differentiated between the ‘control’ and ‘low’ diets in weeks two and five, and tibia continued to show significant differences between the diets into week six.

"It was useful to find foot ash provides a comparable alternative to tibia ash as it is so much easier to retrieve and measure, but there are clear age limitations to when it can be used," said Dawn Scholey, who manages the university's Poultry Unit.

She said: "I think interest in femur ash may grow alongside interest in meat processing efficiency, as carcass femur fractures cause disruptions during processing.”

NTU poultry research group leader Emily Burton added: “As scientists, it is our job to constantly ensure we provide the poultry sector with the best possible ways to measure the impact of their developments.

“This finding is just one segment in a major ongoing project to identify the best methods for assessing skeletal integrity in both broilers and egg laying strains of poultry.”

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Bone type matters in broiler bone ash

Published on 29 August 2017
  • Subject area: Animal, equine and wildlife
  • Category: Press; School of Animal, Rural and Environmental Sciences

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