Abstract
The strength of leg bones is not only genetically determined but it also depends on the gender, age, health condition and nutrition of slaughter birds. Calcium ions deficit in bones results in the deterioration of skeleton structure and reduction of bone strength. The presented work compiles the results of studies concerning the effect of feed additives on the level of calcium in the bones of broiler chickens, published during the past 10 years. From the analysis of available literature it follows that some additives had a positive effect on the accumulation of calcium (e.g. vitamin D, probiotics, prebiotics and synbiotics), some were not very explicit (e.g. ascorbic acid and phytase), while others did not have a significant effect on the accumulation of calcium in bones (e.g. herbs and chelates). It is concluded from our collected information that the use of probiotics, prebiotics and synbiotics offers the best advantages for poultry. These additives, apart from stimulating the accumulation of calcium in bones, also benefit animal health.