APSS 2013 Proceedings - The University of Sydney
APSS 2013 Proceedings - The University of Sydney
APSS 2013 Proceedings - The University of Sydney
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Aust. Poult. Sci. Symp. <strong>2013</strong>.....24<br />
USING THE GEOMETRIC FRAMEWORK TO EXPLORE CALCIUM AND<br />
PHOSPHORUS INTERACTIONS AND THE EFFECT ON BROILER WELFARE<br />
E.J. BRADBURY 1 , S.J. WILKINSON 1 , G.M. CRONIN 1 , P.C. THOMSON 2 ,<br />
A. SACRANIE 3 and A.J. COWIESON 1<br />
Summary<br />
Calcium (Ca) and phosphorus (P) are the two most abundant minerals in bone and<br />
poultry diets; however, they have a complex multifactorial relationship. To explore<br />
the interactive effects <strong>of</strong> Ca and available phosphorus (av.P) on broiler performance<br />
and skeletal health, 600 Ross 308 day old male broilers were fed one <strong>of</strong> 15 dietary<br />
treatments. Diets were formulated to one <strong>of</strong> three total densities <strong>of</strong> Ca: av. P, with a<br />
spread <strong>of</strong> five different ratios (4, 2.75, 2.1, 1.5 and 1.14:1) at each density. Dietary<br />
av.P was more influential on broiler performance than dietary Ca. Feed intake<br />
increased with higher av.P levels, but was inhibited at low levels <strong>of</strong> av.P. Body weight<br />
gain increased rapidly with increasing dietary av.P. Latency to lie results showed that<br />
birds that were fed diets with a 2.1:1 ratio <strong>of</strong> Ca: av. P had the longest standing times,<br />
indicating better leg health.<br />
I. INTRODUCTION<br />
<strong>The</strong> relationship between calcium (Ca) and phosphorus (P) in broiler nutrition is one<br />
that is complex and multifactorial. <strong>The</strong> digestion and absorption <strong>of</strong> these minerals is<br />
influenced by other dietary vitamins and enzymes as well as endogenous hormones.<br />
<strong>The</strong> modern broiler has a high requirement for Ca and P for energy metabolism and<br />
skeletal development. Deficiencies in Ca, P or both nutrients can have negative effects<br />
on bird performance as well as skeletal health. Due to the selection for rapid growth in<br />
broilers, some indirect welfare consequences have arisen; <strong>of</strong> particular importance are<br />
the adverse effects on skeletal health (Shim et al., 2012). Current research shows that<br />
due to the high porosity <strong>of</strong> the cortical bone it is prone to bone deformities, which can<br />
impair broiler mobility, which is considered a welfare concern.<br />
To better understand the complex relationship between Ca and P in poultry<br />
nutrition, a novel graphical approach termed the geometric framework was used. <strong>The</strong><br />
geometric framework allows for a graphical representation <strong>of</strong> two or more nutrients,<br />
and explores the interactive effects <strong>of</strong> these nutrients. This study aims to investigate<br />
the optimum dietary Ca and available P (av.P) concentrations for broiler performance<br />
and skeletal health using the geometric framework.<br />
II. MATERIALS AND METHODS<br />
All experimental procedures conducted had approval from <strong>The</strong> <strong>University</strong> <strong>of</strong> <strong>Sydney</strong><br />
Animal Ethics Committee. A total <strong>of</strong> 600 Ross 308 day-old male broiler chicks were<br />
obtained from a commercial hatchery. Chicks were randomly allocated across 75<br />
cages (750mm x 750mm x 510mm) with eight birds per cage and five replicate cages<br />
per treatment. <strong>The</strong> cages were housed in a temperature controlled room; temperature<br />
<strong>of</strong> 31 °C for the first five days and reduced by 0.5 °C per day until 24 °C (d21). <strong>The</strong><br />
1 Poultry Research Foundation, <strong>The</strong> <strong>University</strong> <strong>of</strong> <strong>Sydney</strong>, Camden, NSW 2570.<br />
2 <strong>The</strong> <strong>University</strong> <strong>of</strong> <strong>Sydney</strong>, Faculty <strong>of</strong> Veterinary Science.<br />
3 Nutreco, Poultry Research Centre, Toledo, Spain.<br />
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