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

Abstract

Summary Background & aims Bone-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. Methods Newborn, 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 55g/L), and equal amounts of fat, carbohydrates, calcium and phosphorus. Results & Conclusion Despite 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). Results Baseline 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). Conclusion Despite immunocompromised conditions, casein and soy protein may promote a better bone development in colostrum-deprived piglets.