APSS 2013 Proceedings - The University of Sydney

Aust. Poult. Sci. Symp. 2013.....24
MINERAL COMPOSITION OF CALCIUM SOURCES USED BY THE AUSTRALIAN
POULTRY FEED INDUSTRY
S.J. WILKINSON 1 , B. RUTH 2 and A.J. COWIESON 1
Summary
A mineral compositional survey of 14 limestone sources commonly used by Australian
poultry feed manufacturers was performed. Samples were wet acid digested prior to the
determination of Ca, P, Mg, Fe, K, Mn, Na, Cu, Sr and Zn concentrations by inductivelycoupled
plasma-optical emission spectroscopy. The results from this survey show large
differences between the highest and lowest determined concentrations in all of the minerals
analysed and in particular those of P (241 mg/kg), Na (186 mg/kg), Mn (237 mg/kg), Fe
(1397 mg/kg) and K (125 mg/kg) values. Data from this survey indicate that the trace
mineral composition of limestone sources is variable and that these values may need to be
considered as a part of standard quality control procedures.
I. INTRODUCTION
Limestone is composed primarily of CaCO 3 and is commonly used as a source of calcium
(Ca) in poultry diets. Pure CaCO 3 has a molecular weight of approximately 100g/mole and
so is around 400 g/kg Ca. However, CaCO 3 sources used in animal feeding are typically only
370-380 g/kg Ca, sometimes less, due to the presence of other minerals such as Mg or Fe.
Furthermore, the bioavailability of Ca to the bird is affected by many factors including the
source of Ca, solubility, gut retention time, particle size as well as the presence of other
minerals (Oso et al., 2011). A paucity of information detailing the mineral composition of
commonly used Ca sources is available to the Australian poultry industry. This paper reports
on the determined mineral composition of 15 samples of Ca sources commonly used in the
Australian poultry feed manufacturing industry.
II. MATERIALS AND METHODS
Fourteen samples of limestone (CaCO 3 ) in the form of powder (N=13) and grit (N=1) were
obtained from various feed mills and distributors throughout Australia. Samples were wet
acid digested using nitric acid and hydrogen peroxide (Peters et al., 2003) prior to the
determination of Ca, P, Mg, Fe, Cu, K, Mn, Na, Sr and Zn concentration by Inductively
Coupled Plasma-Optical Emission Spectroscopy using a Perkin Elmer OPTIMA 7300 (Perkin
Elmer Inc, Waltham, MA, USA). All samples were analysed as received in triplicate. Results
are sample means presented as g/kg for Ca and Mg and as mg/kg for Fe, K, Mn, Na, Sr and
Zn. The concentration of P is reported as mg/kg for all samples except those reported as
g/kg.
III. RESULTS AND DISCUSSION
The results for the determined mineral composition are shown in Table 1. For all samples, the
concentration of Cu was below detectable limits and is not reported. All samples contained
higher than expected Ca concentrations and when combined with the micro-mineral results
this suggests that the samples were not pure CaCO 3 . Calcium concentrations ranged from
1 Faculty of Veterinary Science, The University of Sydney. stuart.wilkinson@sydney.edu.au
2 Ruth Consolidated Industries. bsruth@rci.com.au
45