Bone Composition in Male and Female Göttingen Minipigs Fed Variously Restrictedly and Near ad Libitum

The current study evaluated the influence of restricted feeding at low and medium levels versus near ad libitum food intake, on the growth and bone development in male and female Göttingen minipigs aged 8 to 43 weeks fed two different types of diets. Diet 1 was a low fat, high fibre diet, whereas diet 2 was a high fat, low fibre diet. A higher level of feed intake led to a significant increase in the following parameters: body weight development, bone size (length and width of rib and femur), bone volume (rib), bone (rib) dry matter and ash content (mg), as well as bone density (femur) as measured by X-ray absorption. Diet 2 gave a significantly higher body weight, bone volume and bone density of the femur shaft (cortical bone density) as compared to diet 1, whereas feed conversion was significantly lower on diet 2. On either diet, female minipigs had a significantly higher body weight development, bone volume, and dry matter and ash content of the rib (mg) as compared to males. Also bone mineral concentrations in the femur, expressed as calcium, phosphorus and magnesium in mg/cm3, were significantly higher in females as compared to males, as was the Ca:Pi ratio. Bone density measurements of the femur’s proximal and distal segment, and total femur bone density (g/cm2) were significantly higher in females as compared to males. Feed conversion in females was significantly lower than in males. This study illustrates that female and male minipigs show distinct differences in body and bone metabolism. Bone densities, in contrast to bone mineral concentrations, were related to the level of feed restriction and may therefore be useful biomarkers to study the influence of nutrient intake on bone metabolism in Göttingen minipigs.