Effects of 25-hydroxycholecalciferol and soy isoflavones supplementation on bone mineralisation of quail

1. The effects of 25-hydroxycholecalciferol (25-OH-D3) and soy isoflavones supplementation on performance, carcase recovery, bone mineral density, and tibia ash, Ca, P, and serum vitamin D concentrations and alkaline phosphatase activity in the Japanese quail (Coturnix coturnix japonica) exposed to high ambient temperature were evaluated. 2. A total of 270 ten-d-old Japanese quail were randomly assigned to 9 treatment groups, 6 replicates of 5 birds each in a 2 x 3 x 3 factorial arrangement of treatments. Birds were kept in a temperature-controlled room at either 22 degrees C (thermo-neutral) or 34 degrees C (heat stress) for 8 h/d (09:00-17:00 h) and given a basal (control) diet or the basal diet supplemented with one of three levels of 25-OH-D3 (0, 250 and 500 IU/kg of diet) combined with one of three levels of soy isoflavones (0, 400 and 800 mg/kg of diet). 3. Birds kept at 34 degrees C consumed less feed and gained less weight than control birds. An increase in body weight, feed intake (and improvement in feed efficiency and carcase recovery were found in soy isoflavones and 25-OH-D3-supplemented quail reared under heat stress conditions. Bone mineral density, tibia ash, Ca, and P were linearly improved by 25-OH-D3 and soy isoflavones supplementation in both thermoneutral and heat stress groups. Serum vitamin D levels and alkaline phosphatase activity were improved by 25-OH-D3 and soy isoflavones supplementation in both thermoneutral and heat stress groups in quail. 4. In conclusion, a combination of 25-OH-D3 and soy isoflavones supplementation to basal diet significantly improved bone mineralisation in quail.