The unsolved mystery of Aotearoa: Spontaneous humeral fractures in first lactation dairy heifers.

Abstract

In New Zealand spontaneous humerus fracture in first lactation dairy heifers has been reported. There has been an apparent sudden increase in the number of cases over the last seven to eight years. The syndrome leads to an estimated loss of 5000 dairy heifers every year which represents major economic and welfare loss. It is hypothesised that spontaneous humeral fractures are occurring as a result of skeletal fragility that may be due to growth check during the rearing period rather than a specific traumatic event in early lactation. This study examined the effect of age and different feeding regiments on morphological measures of bone and measures of bone development and the correlation between measures of bone development. Peripheral quantitative computer tomography scanning was conducted on the mid-diaphyseal region of the third and fourth metacarpal bones of the right forelimb of 24 KiwiCross calves. The results of this research indicate that restricted feeding during the first 12 weeks of the life of a calf does not cause a difference in bone strength. This pilot study addressed only one aspect of this multifactorial problem. Implications and suggestions for future research are discussed.