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Abstract
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This study was carried out to evaluated the effects of various levels of strontium on osteoporosis, bone density and eggshell quality in 180 Hy-Line W-36 of laying hens from 38-48 weeks of ages. Experiment was arranged in a completely randomized design (CRD) including 6 treatments, 5 replicates cages and 6 birds in each. Experimental treatments consisted of control diet contains corn and soybean meal (without strontium) and 2, 3, 4, 5 and 6 including 1, 2, 3, 4 and 5 gr strontium carbonate per kg of diet, respectively. The bone density was measured by X-ray for osteoporosis at 46 weeks of ages. Egg quality and quantity were measured biweekly. Results have indicated that there was a significant increase in ash contents, bone volume and density of leg bone in all treatments compared to the control diet (P<0.0001). Shape index, shell weight, shell ratio and shell thickness were not affected by different levels of strontium enduring the experimental period (P>0.05). Higher levels of bone strontium and calcium were shown in treatment 5 (p<0.05). Bending strength, density and leg bone weight were observed in the experimental groups. On the other hand, there were no significant differences in maximum strain, resistance to break and elasticity of bones. In general, the results of this study have shown that the level of 3 gr carbonate strontium/ kg diet could be considered to increase bone density and reduce osteoporosis. It is a good strategy for increasing resistance to bone fracture of laying hens. In addition, no adverse effects were observed on egg quality, quantity and bone parameters of lying hens.
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