Osteoporosis is the cause of spontaneous humeral fracture in dairy cows from New Zealand.

Outbreaks of humeral fractures in dairy cows have been reported in New Zealand for several years. Gross, histologic, and histomorphometric findings in the humerus from primiparous cows with spontaneous humeral fracture were compared to age-matched control cows. Affected cows had a complete nonarticular spiral fracture of the humerus. Histologically affected humeri had a thicker growth plate with abnormal architecture, thinner cortex with increased abnormal resorption, increased resorption in the distal humerus, decreased trabecular density, abnormal trabecular architecture, presence of growth arrest lines and woven bone formation. Histomorphometry showed reduction in bone volume, trabecular perimeter, and trabecular width. Cows grazed on fodder beet had thicker growth plates with an abnormal appearance compared with cows grazed on pasture, and cows with low/marginal liver copper concentration had more resorption cavities in the distal humerus and thinner cortical bone compared with cows with adequate liver copper concentration. Decreased trabecular density (OR = 249.5), abnormal cortical resorption (OR = 54.2), presence of woven bone formation in the proximal metaphysis (OR = 37.2), and the number of resorption cavities in the distal humerus were significantly associated with a high probability of fracture. Ribs had enlargement of the costochondral junction with fractures in different stages of healing. Histology of the ribs revealed abnormal growth plate appearance, presence of fracture lines, callus tissue, fibrosis, and microfractures. Cows with humeral fracture have osteoporosis due to decreased bone formation and increased bone resorption, likely associated with inadequate feed quality and perhaps copper deficiency leading to a reduction in bone strength and fracture.

Bone quality changes as measured by Raman and FTIR spectroscopy in primiparous cows with humeral fracture from New Zealand.

The occurrence of spontaneous humeral fractures in primiparous dairy cows from New Zealand prompted the study of bone material from affected cows to further characterize this condition and to outline a likely pathogenesis. Previous studies indicate that these cows developed osteoporosis due to periods of suboptimal bone formation followed by increased bone resorption during the period of lactation complicated by copper deficiency. We hypothesized that there are significant differences in the chemical composition/bone quality in bones from cows with spontaneous humeral fracture compared to cows without humeral fractures. In this study, Raman and Fourier transform infrared spectroscopy band ratios were, for the first time, measured, calculated, and compared in bone samples from 67 primiparous dairy cows that suffered a spontaneous fracture of the humerus and 14 age-matched post-calving cows without humeral fractures. Affected bone showed a significantly reduced mineral/matrix ratio, increased bone remodeling, newer bone tissue with lower mineralization and, lower carbonate substitution, and reduced crystallinity. As such, is likely that these have detrimentally impacted bone quality and strength in affected cows.

The microenvironment of the ovarian follicle in the postpartum dairy cow: effects on reagent transfer from cumulus cells to oocytes in vitro.

This study's hypothesis was that the nutrient composition in follicular fluid (FF) of ovarian follicles in early lactating postpartum cows may influence reagent transfer from cumulus cells (CC) to the oocyte. To test this, concentrations of amino acids (AA), cholesterol, glucose, and nonesterified fatty acids were measured in FF from the largest antral follicles at Days 21 and 46 postpartum during which time, most animals were expected to have resumed ovulatory activity. From the range of concentrations measured, two media compositions (Lac and Half-Lac) were prepared to compare with medium 199 (M199). The AA and cholesterol concentrations in FF were on average, approximately 35% and greater than 1000% higher than in M199, respectively. The nonesterified fatty acids, but not glucose, concentrations also exceeded those in M199. The transfer of fluorescent dye from CC to oocytes in bovine cumulus-oocyte complexes incubated with and without phosphodiesterase inhibitors (dipyridamole and milrinone) and/or forskolin was assessed. Maximum dye accumulation in oocytes incubated in M199 occurred after 4 hours and was further increased (P < 0.001) by dipyridamole. The addition of dipyridamole to Lac, but not Half-Lac, media also increased dye accumulation. There were effects of media (P < 0.001), cholesterol (P < 0.001), and forskolin (P < 0.05) on dye accumulation but no effects of stearic or palmitic acid in either Lac or Half-Lac media. The addition of oleic acid in Half-Lac (P < 0.01), but not Lac, media inhibited dye accumulation. These results support the hypothesis that reagent transfer from CC to oocytes is compromised when the AA composition in FF is low, as sometimes occurs during early lactation.