Effect of Organic Acids and Prebiotics on Bone Quality in Laying Hens Fed Diets with Two Levels of Calcium and Phosphorus

In an experiment conducted on caged Bovans Brown hens, the effect of diet supplementation using organic acids and prebiotic fructans on the biomechanical and geometrical indicators of the tibia and femur bones was evaluated. At 25 weeks of age, layers were randomly assigned to 14 experimental groups, each comprising 6 hens kept in individual cages. A 2 x 7 factorial arrangement, with two dietary levels of calcium and phosphorus (normal - 37.0 g Ca/kg, 6.5 g P/kg, and reduced - 32.5 g Ca/kg, 6.0 g P/kg), and with diets supplemented by selected additives (none; inulin, 7.5 g/kg; oligofructose, 7.5 g/kg; short chain fatty acids (SCFA), 5.0 g/kg; medium chain fatty acid (MCFA), 2.5 g/kg; SCFA, 3.0 g/kg + MCFA, 2.0 g/kg; inulin, 3.0 g/kg + SCFA, 5.0 g/kg) was used. The experiment was conducted for 45 weeks and concluded when the hens were 70 weeks old. At 70 weeks of age, reducing the dietary levels of Ca and P had decreased the bone breaking strength by 8.9% (P &#x2AAC 0.001) and the yielding load by 5.6% (P &#x2AAC 0.05). A similar tendency for bone breaking strength (P &#x2AAC 0.05) and stiffness (P &#x2AAC 0.05) was found in the femur bones. The diet with a lower level of Ca and P negatively affected the geometrical indicators of the bones such as cortex thickness (P &#x2AAC 0.05) and cross section area (P &#x2AAC 0.05), but had no effect on bone weight and length. Hens fed diets supplemented with oligofructose, MCFA, SCFA + MCFA or inulin + SCFA displayed a significantly higher bone breaking strength and yield load in the tibia bone than that of the control group. In the case of femurs, a positive influence of MCFA or simultaneous addition of inulin + SCFA on bone breaking strength was found. The additives had no significant effects on the geometrical indicators of either bone. It was concluded that selected feed additives which lower the pH of the diet and intestinal content can beneficially affect the biomechanical indicators of the bones of high-productive laying hens