Bone Morphology and Strength in the Mid-Diaphysis of the Humerus and Metacarpus in Dairy Calves Prior to Weaning

Abstract

Calf growth rate in relation to future milk production has been thoroughly studied; however, the observation of growth arrest lines in bones from heifers with humeral fractures has highlighted the need to understand bone growth in relation to calf growth. The aim of this study was to describe the relationship of peripheral quantitative computed tomography (pQCT)-derived measures of bone strength and morphology with gross measurements of size and growth in pre-weaning dairy calves. Liveweight, height, body length, girth and leg length were measured at one, six and twelve weeks of age. At these intervals, the mid-diaphysis of the metacarpus was also scanned in the live animal using pQCT. At six and twelve weeks old, a subset of calves were euthanised and the humerus was collected and scanned at the mid-diaphysis using pQCT. Differences in growth patterns were observed between the metacarpus and humerus over time. Weight was the best predictor for measures of periosteal circumference and stress strain index (R2 = 0.49–0.58) in the metacarpus, and also the best predictor for measures of stress strain index at all ages in the humerus (R2 = 0.94). The strong relationship with weight and bone measures emphasises the need for adequate preweaning nutrition for future bone growth.

The Effect of Sex and Age on Bone Morphology and Strength in the Metacarpus and Humerus in Beef-Cross-Dairy Cattle

“…The results in the present study agree with an earlier observation from a younger cohort of cattle that identified live weight as the major explanatory variable for measures of bone mass and strength in the metacarpus and humerus [ 3 ]. In addition, in the current study, it was demonstrated that the relationship of live weight with measures of bone mass and strength was modified by age and sex.…”

“…The pQCT scanning was carried out using the same protocol previously reported by Gibson et al [ 3 ]. Briefly, pQCT scanning was carried out using an XCT 2000 peripheral quantitative computed tomography machine (Stratec Medical, Pforzheim, Germany).…”

“…As live weight increases, bone must increase in size and strength to maintain strain within physiological limits [ 1 ]. The application of this theory has been supported by research looking in to the relationship between bone and strain where increases in live weight or loading result in a rise in bone strength [ 2 , 3 ]. The nature and magnitude of the bone response is dependent on the region within the bone and the stage of maturation of the animal.…”

The Mid-Diaphysis Is a Poor Predictor of Humeral Fracture Risk Indicating That Predisposing Factors Are Recent

“…Bone size and strength have been shown to be strongly correlated with live weight [6,7]. Due to the opportunistic nature of bone acquisition in both the control and affected groups, live weights could not be consistently or reliably obtained.…”

“…pQCT scanning was carried out using the same protocol previously reported by Gibson, et al [6] and Gibson, et al [7]. Briefly, pQCT scanning was carried out using an XCT 2000 peripheral quantitative computed tomography machine (Stratec Medical, Pforzheim, Germany).…”