Optimising the use of phosphorus sources in growing meat ducks

Abstract

Optimal utilisation of limited phosphate resources in animal feeding requires detailed knowledge of both the requirement for available phosphorus (P), and the availability of P from relevant feed ingredients. In growing ducks, the P concentration of gained body weight and the inevitable P losses voided determine the requirement for available P. The concentration of available P needed in the diet then depends on the feed conversion ratio. Plant and mineral feedstuffs contribute to the available P content of the diet depending on their respective availability. This review summarises the literature on P nutrition in ducks with regard to factors affecting P requirement and considerations of P availability, including the use of microbial phytase. Most of the published data refer to the Pekin duck. The P content in body weight gain is 5.0-5.5 g/kg in young ducks, and it probably decreases with age. The ratio of Ca to P in body weight gain is about 1.8:1. Inevitable P losses are not yet quantified and can only be estimated to account for 1 g/kg of feed intake. Availability of P from plant-based diets without P supplements and phytase ranged between 28 and 49%. Availability of P from different mineral sources ranged between 77 and 100%. Microbial phytases were efficient in improving the availability of P from plant-based diets. A simple model is presented, which allows flexible calculations to be made of the necessary P concentrations in the diets for ducks. The most efficient tool for reducing the use of P sources is the frequent adjustment of the dietary P content during the growth period. Data from growth studies indicate that the suggestions made herein are sufficiently safe for application in Pekin duck feeding.

Keywords::

• ducks
• growth
• phosphorus
• requirement factors
• utilisation
• phytase
• model