Calculations and statistical analyses
The colour parameters were L*, lightness, which
ranges from 0 for black to 100 for white, a* for
red/green chromaticity and b* for yellow and blue
chromaticity, in accordance with the recommendations
of the International Commission on Illumination
(CIE 1976). From the a* and b* values, the
hue (Hab) and chroma (Cab) values were calculated.
Hue, namely the visible colours in the electromagnetic
spectrum (e.g. red, blue and yellow), provides
an angular measurement where 08 indicates a red
hue, 908 denotes a yellow hue, 1808 green and
2708 blue. Hue is calculated using the equation,
Hab = arctan (b*/a*) (Hunt 1977). Chroma is an
expression of saturation or intensity of the colour
attained and is expressed by the equation,
Cab = (a*2 + b*2)1/2 (Hunt 1977). Data were
analysed statistically using analysis of variance
(ANOVA) for feeding type (Steel & Torrie 1980). Significant
differences among means (P 0.05)
were ranked using Duncan’s new multiple range
tests. The results were presented as means SD
and significance was indicated when P 0.05.