This is perhaps a special adaptation
mechanism developed by natural selection in the
evolution of buffaloes, the animal with the lower
glomerular fi ltration rate (GFR) being better able to
survive. The cause of low urinary excretion of PD
in buffaloes could possibly be due to differences
in the GFR (Chen and Ørskov, 2004; Thanh and
Ørskov, 2006). A recent study clearly demonstrates
a lower GFR in buffaloes compared with cattle so
the nitrogen source from plasma stays in the blood
longer (Thanh and Ørskov, 2006; Thanh et al.,
2009).
Another special mechanisms may be
the greater permeability of the buffalo’s rumen compared to that in cattle when we have seen the
purine excretion in urine was lower in buffaloes
than cattle, a fi nding supported by the work of other
scientists (Chen (1989); Chen and Orskov (2004);
IAEA (1997); Joint FAO/IAEA (2003); Liang et al.
(1999, 2005)). This seems to happen only when the
rumen is developed; before that, when the animal is
just suckling milk from its mother or milk bottles,
which means the rumen has not yet developed,
the purine (allantoin and uric acid) excretion in
the urine of buffaloes is the same as that in cattle
(Thanh et al., 2009). So the rumen structure may
also be a special adaptation in the evolution of the
buffalo