Calcium Nutrition of Broilers: Current Perspectives and Challenges

SIMPLE SUMMARY: Calcium (Ca) is essential for the skeletal growth and a plethora of other functions in broilers. Calcium is closely related to phosphorus (P) in terms of absorption and postabsorptive utilisation of both minerals. However, the oversupply of Ca and its potential antinutritive effects in commercial broiler diets are currently receiving attention. In recent decades, considerable attention has been directed towards the P nutrition of poultry because P is the third most expensive nutrient in poultry diets and is a major contributor to environmental pollution. To improve P utilisation and conservation, the poultry industry is moving to a digestible P system from the historically used nonphytate or available P. Thus, there is an urgent need to develop a digestible Ca system in order to meet the requirement of birds and generate accurate digestible Ca to digestible P ratios. During the last decade, considerable progress has been made to define the availability of Ca and P in terms of ileal digestibility. The specific aim of the present overview was to highlight the recent advances in the measurement of ileal Ca digestibility of Ca sources and digestible Ca requirement of broilers. Aspects of homeostatic control mechanisms, Ca sources and the factors influencing Ca digestibility are also addressed. ABSTRACT: Calcium (Ca) plays an essential role in poultry nutrition as 99% of Ca is located in birds’ skeletal system. However, oversupply of Ca rather than deficiency of Ca is the current concern in commercial broiler diets. Calcium is an inexpensive dietary nutrient due to the cheap and abundant availability of limestone, the major Ca source; therefore, little attention was given to the oversupply of Ca in the past. The recent shift in the use of digestible P in broiler feed formulations has necessitated a closer look at digestible Ca, as Ca and P are interrelated in their absorption and postabsorptive utilisation. In this context, data on ileal digestibility of Ca and P in ingredients has been determined. Preliminary data on the digestible Ca and digestible P requirements for the different growth stages of broilers have also recently become available. The present review focusses on these recent advances in Ca nutrition. In addition, aspects of homeostatic control mechanisms, different Ca sources and factors influencing Ca digestibility in poultry are covered.