Vitamin D, Strontium and Laying Hens – What’s the Connection?

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 mg/kg, 1000 mg/kg) and two levels of vitamin D3 (2,500 iu/kg, 5,000 iu/kg). There was an improvement (P < 0.05) in egg production and feed conversion efficiency with strontium at 500mg/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 2,500 iu D3/kg but reduced phosphorus, sodium and strontium retention in birds fed 5,000 iu D3/kg resulting in an interaction (P < 0.01) between strontium and vitamin D3. Addition of 5000 iu/kg D3 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 metabolisable energy (P < 0.05); in contrast strontium supplementation reduced (P < 0.05) apparent metabolisable energy. The interrelationship between strontium and vitamin D3 requires further study.