Comparison of herbage intakes estimated from in vitro or
alkane-based digestibilities
H. Dove; J.A. Milne; R.W. Mayes
CSIRO Division of Plant Industry, Canberra, Australia
Proceedings of the New Zealand Society of Animal Production.
1990, 50: 453-454
In 34 lactating ewes (10 fistulated at the rumen and abomasum),
herbage intakes were calculated using herbage digestibilities estimated
either in vitro, or by using the plant cuticular wax component
pentatriacontane (C35 alkane) as an internal marker. Alkane-based
herbage intakes in intact ewes rose from 1672g OM/d at 14d of lactation
to 2798g OM/d at 42d. In the fistulated ewes, the equivalent herbage
intakes were 1736 and 2240g OM/d respectively. Alkane-based and in
vitro-based intakes were not significantly different at 14d of
lactation in either intact or fistulated ewes. Later in lactation,
alkane-based intakes were significantly higher in both groups of ewes.
In the fistulated ewes, estimates of the proportion of digested OM
apparently disappearing across the rumen and of the efficiency of
microbial protein synthesis were calculated from abomasal flows of
digesta and microbial protein. These results suggested that the alkane-
based herbage intakes were the more accurate.
Keywords: NZSAPAB;
Intake; alkanes; in vitro digesta flow; microbial
protein; lactation; ewes
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Last Updated 25-01-1997
