Interactive effects of vitamin D^sub 3^ and strontium on performance, nutrient retention and bone mineral composition in laying hens

Strontium is currently prescribed for patients with osteoporosis to increase bone density and reduce bone fractures but its relevance in animal nutrition is obscure. In order to investigate the effect of supplemental strontium and vitamin D3 on performance, egg quality and skeletal integrity in poultry a total of 108 laying hens, 99 weeks of age, were fed three levels of strontium (0, 500, 1000 mg kg...) and two levels of vitamin D3 (2500, 5,000 iu kg...) over a 12-week period. There was an improvement (P < 0.05) in egg production and feed conversion efficiency with strontium at 500 mg kg... and a significant increase in egg weight in those hens fed additional vitamin D3. Supplemental strontium increased phosphorus, sodium and strontium retention in birds fed 2500 iu D3 kg... but reduced phosphorus, sodium and strontium retention in birds fed 5000 iu D3 kg..., resulting in an interaction (P < 0.01) between strontium and vitamin D3. Addition of 5000 iu D3 kg... increased egg weight (P < 0.05); predominantly by increased albumen content (P < 0.05), whereas strontium supplementation reduced egg weight (P < 0.001). Similarly, 5000 iu kg... D3 increased apparent metabolizable energy (P < 0.05); in contrast, strontium supplementation reduced (P < 0.05) apparent metabolizable energy. The addition of 500 mg kg... strontium significantly improved egg production and feed efficiency; however, further investigation needs to be undertaken to refine the optimum level of strontium required to maximize hen performance. The interrelationship between strontium and vitamin D3 requires further exploratory study. (ProQuest: ... denotes formulae/symbols omitted.)