A total of 156 compounds were identified from these
samples. There was considerable individual variation in the
presence or absence of different compounds identified at
various stages. Urine is a highly complex biological material;
the nature of its chemical constituents depends on the
endocrine status and body temperature, as well as on the
genetic background [20]. Another interesting observation
was that certain compounds that were detected in the individual
sample of a particular stage were not present in
the pooled sample. Again, certain other compounds could
be found in the pooled sample, but were not present in any
of the individual sample. It could be possible that after
pooling of the urine samples, some changes may have
occurred in the chemical conformation of the compounds,
which were detected in the individual samples, resulting in
the formation of a different/new chemical compound. Thus,
some compounds that were detected in the pooled samples
could be the mixture of two or three compounds detected
in the individual samples. A compound was therefore
considered to be present at a particular stage only when it
was found in 50% or more samples. Thus, a compound was
considered to be present if found in at least four out of
seven estrus samples, three out of five diestrus, three out of
six pregnancy, and four out of seven bull urine samples.
Twenty-one compounds were finally identified on the basis
of this criterion (Table 1). The constituents identified in
the urine samples belonged mainly to alkanes, alcohols,
amides, amines, ketones, and phthalates. Among the
different compounds, alkanes were predominantly present
compared with all the other constituents.