Total lipids, triglycerides, and phospholipids were measured with
colorimetric assays in a Shimadzdu spectrophotometer (Chaudhry,
1989) in 10 semen samples (the 5 used for fatty acid analysis and in 5
additional ones). For determination of total lipids a sulphuric acid–
vanillin–benzoic acid reagent was used. Triglycerides were saponifi-
cated, the resulting glycerol was oxidized with sodium metaperiodate
to formaldehyde and formaldehyde was condensed with acetylacetone
and ammonia to form 3,5-diacetyl-1,4-dihydrolutidine. Phospholipids
were digested with nitric acid and the liberated phosphate
was measured. Cholesterol was determined with an enzymecolorimetric
assay of Allain et al. (1974)