Interactive effect of vitamin D and strontium on performance and bone composition in broiler chickens

Vitamin D and strontium have a close physiological interrelationship in respect to mineral homeostasis and skeletal integrity which is not well defined. To elucidate this relationship a total of 960-day-old male broiler chickens were fed for 40 days one of eight diets comprising of two levels of vitamin D-3 (5000 or 10,000 IU/kg) and four levels of strontium (0, 400, 800 or 1200 mg/kg). Bodyweight gain, feed intake, bone composition and ileal nutrient digestibilities were analysed. All treatments improved BWG in excess of breed Ross 308 expectations and there was no statistical difference in overall performance between treatments. In the starter period, higher vitamin D-3 interacted with the highest level of strontium supplementation to reduce BWG (P<0.05) and increase FCR (P<0.05). There was no change in percentage tibia ash content between treatments. Increasing concentrations of dietary strontium resulted in a reduced Ca content (P<0.01) and an increase in strontium (P<0.0001), Mg (P<0.01) and K content (P<0.05) of bone. The ileal digestibility of sodium was reduced in birds fed higher vitamin D-3 with the highest level of strontium supplementation (P<0.05). There was no improvement in BWG or FCR by day 40 with higher levels of vitamin D-3 and various levels of supplemental strontium however performance was negatively affected in the starter phase. Strontium supplementation in the presence of additional vitamin D-3 altered tibia bone composition and reduced Na Heal digestibility. The ratio of 30:1 for calcium to sodium in bone was maintained across all treatments as did the total percentage content of calcium, sodium, strontium, potassium and magnesium at 43%. The higher level of vitamin D-3 (10,000 IU/kg) with no added strontium (0 mg/kg) produced the heaviest BWG per bird by day 40 (3157 g) however it was not statistically significant. The higher level of vitamin D-3 significantly increased mortality. The feeding of lower doses of strontium and vitamin D-3, particularly in the starter phase, requires further investigation. (C) 2015 Elsevier B.V. All rights reserved.