Effects of casein, whey and soy proteins on volumetric bone density and bone strength in immunocompromised piglets

SummaryBackground & aimsBone-promoting effect of different proteins in early life, under immunocompromised conditions, is unknown. We investigated effects of milk- and plant-derived proteins on bone development in immunocompromised piglets.MethodsNewborn, colostrum-deprived piglets were assigned to a formula based on either casein (n=11), whey (n=11) or soy (n=10) as the protein source (each 55 g/L), and equal amounts of fat, carbohydrates, calcium and phosphorus.Results & ConclusionDespite efforts to sustain immuno-protection (sow serum and antibiotic injections), some piglets became sick and were early euthanised. After 6 days, bone density (peripheral quantitative computed tomography), bone mechanical strength (three-point bending test) and serum insulin-like growth factor-I (sIGF-I) (immunoassay) were measured in the surviving piglets (casein n=5, whey n=9, soy n=5).ResultsBaseline body weight was not significantly different between the groups and between early euthanised and surviving piglets. After 6 days, all piglets showed depressed growth and low sIGF-I levels. At trabecular sites, whey reduced bone mineral density compared with casein and soy (P⩽0.01), and reduced mineral content compared with casein (P⩽0.01). Whey decreased cortical thickness and bone strength compared with casein (P⩽0.04).ConclusionDespite immunocompromised conditions, casein and soy protein may promote a better bone development in colostrum-deprived piglets.