ISSN:
1439-0426
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Biology
,
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
An attempt was made to measure the apparent digestibility (AD) of cholesterol and fatty acids using 5aL-cholestane as a marker (cholestane-method) using tilapia. Oreochromis niloticus, and the freshwater prawn, Macrobrachium rosenbergii, as test animals. The results were compared with those obtained by the Cr2O3-method. Casein-based test diets containing 0.3% levels of cholestane and chromic oxide as markers were prepared for determination of AD of dietary cholesterol and fatty acids. After 2 weeks of acclimation, the test animals, tilapia (average 3.0 g wet weight) and freshwater prawn (average 0.5 g wet weight) were fed the test diets for 1 week, and faecal samples were collected over 6 subsequent days. Lipids in the diets and faeces were extracted with chloroform-methanol and saponified with 10% KOH in methanol. Gas-liquid chromatography (GLC) on 1.5% OV-17 of the unsaponifiable matters afforded the quantities of 5aL-cholestane and cholesterol, whereas that on 5% Shinchrom E-71 of the saponifiable matters provided the quantities of fatty acids. Chromic oxide was determined by a wet-digestion method. In tilapia, the AD of cholesterol determined by cholestane- and Cr2O3-methods were 78.1% and 73.5%, respectively. The AD of individual fatty acids differed with the types of fatty acids, but those of fatty acids determined by the two methods in this study were similar, except for a slightly higher value of several fatty acids such as 16:1 in the cholestane-method than in the Cr2O3-method. This indicates that 5α-cholestane as well as Cr2O3 can be conventionally used as a marker for determining AD of fatty acids and cholesterol. The cholestane-method is advantageous as it permits parallel analysis of cholesterol (or fatty acids) and 5α-cholestane by GLC using small amounts of faecal sample. The cholestane-method was also useful for analysing digestibilities of cholesterol and total lipids in freshwater prawn. However, slight differences between the cholestane- and Cr2O3-methods were observed in the AD of several fatty acids such as 14:0 and 16:1.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1439-0426.1997.tb00095.x
