A re-evaluation of calcium and phosphorous requirements for optimal performance and bone integrity of the Ross 308 broiler

Abstract

Calcium and phosphorus are vitally important macro minerals and are the most abundant minerals found in the broiler, playing a vital role in bone development and mineralisation. Phosphorus also plays an important role in growth as it is prevalent within nucleic acids, nucleotides, phospholipids and phosphorylated proteins. Considering the fast growth rate of the broiler and the rapid production cycles that the modern broiler is exposed to, it should be essential to have the correct levels of Ca and P in the broiler diet. There is a likelihood that nutritionists have been over supplementing these minerals due to the lack of understanding of their absorption rates and bioavailability and how they interact with each other. As a result very large safety margins are applied due to fear of causing deficiencies. As phosphorus is the third most expensive ingredient in a broiler diet, it would also be of economic advantage if the inclusion levels are dropped without negatively influencing performance and health. New research suggests that the Ca and P levels in a broiler diet can be safely reduced compared to the levels that nutritionists have been supplementing up to now. The main objective of this study was to determine if feeding lower levels of Ca and P to broilers throughout the rearing period compared to the current South African industry standard for Ca and P inclusion levels (308 Ross Broiler management manual, 2009) would affect body weight gain and performance as well as bone mineralisation. Other objectives of the study were to determine if reducing Ca and P levels in finisher feed would compromise bone integrity and also to determine the effect of the interaction between Ca and P at various inclusion levels on requirement levels in the broiler in terms of growth performance, bone mineralisation, phosphorous excretion and profitability of broiler production.