APSS 2013 Proceedings - The University of Sydney

Aust. Poult. Sci. Symp. 2013.....24
RELATIONSHIP BETWEEN THE APPARENT METABOLISABLE ENERGY AND
GRAIN CHARACTERISTICS OF MAIZE
D.V. THOMAS 1 , A. HARDACRE 1 , S.M. RUTHERFURD 2 and V. RAVINDRAN 1
Maize is an important energy source in poultry feed formulations in New Zealand. No
published data are available on the variability in apparent metabolisable energy (AME)
content of maize grown in New Zealand. A total of 24 samples, representing 8 cultivars, were
collected from different growing locations in the North Island. The samples were subjected to
the measurement of various grain characteristics (bulk density [BD], 50g kernel number
[KN], protein content, oil content and stenvert hardness [SH]). The AME was assayed using
the rapid method of Farrell (1978) with two modifications. Male broiler chickens (28-day
old) were used instead of adult cockerels and assay diets containing 965 g/kg wheat and 35
g/kg vitamin and mineral supplements were used instead of substituting 500 g/kg of the
cereal into a sorghum-basal diet. Each assay diet, in mash form, was offered ad libitum to
four replicates (6 birds/ replicate) per sample. The correlation coefficients of AME with the
grain characteristics were calculated. As summarised in the Table below, the AME of maize
samples showed considerable variation, ranging between 11.86 and 14.81 MJ/kg dry matter.
Cultivar Number of
samples
Average AME
(MJ/kg dry matter)
Range
(MJ/kg dry matter)
1 4 12.97 12.82 – 13.20
2 4 13.58 13.12 – 14.22
3 2 13.51 13.32 – 13.69
4 2 13.70 13.58 – 13.81
5 5 14.10 13.31 – 14.81
6 2 13.61 13.60 – 13.61
7 2 13.59 13.58 – 13.61
8 3 12.91 11.86 – 13.65
The variation determined in grain characteristics were: BD, 52.8 to 80.9 kg/hl; KN,
134 to 258 kernels; protein content, 76 to 113 g/kg; SH, 2.9 to 9.6 kj; and oil content, 25 to
42 g/kg. The AME was not correlated with protein content (r=-0.01; P=0.98) and poorly
correlated with BD (r=0.37; P=0.11). Significant correlations were observed with KN (r=-
0.49; P