Bone mineralisation and strength in range cattle

Abstract

Cattle (358) from western New South Wales were sampled at abattoirs as part of a survey of mineral status of range cattle. Each animal was described for breed, sex, age, and body condition, and their origin traced back to their range, which was described for forage offered and soil type. Rib bone samples were taken for chemical and mechanical analyses to provide data on percentage phosphorus (% P) and percentage calcium (% Ca) (fat-free bone), percentage ash, ash density, matrix density, ash : matrix, bending moment, and deformation.

A tree-based classification model was used to form groups of animals with common background factors (e.g. soil, age, sex, weight). Several of these groups were suspected of being osteodystrophic based on the chemical and physical data. Young cows and cattle in poor body fat condition on poor quality forage were at risk and should have responded to phosphorus supplementation with rain and better pasture conditions.

Identification of osteodystrophy in these cattle was most readily diagnosed from ash density data and not from % P, % Ca, or Ca : P. Bone strength interpretation was limited to young cattle. Reference values, as an indication of normal range, are provided for each of the parameters.