Starch manipulation in
ruminants for growth,
production and health
Introduction
• High producing ruminants are fed on a high
concentrate to forage ratio diets for high production
of milk and meat.
• Starch from grains- maize, barley and wheat is
broken down by ruminal microbes to produce
energy-VFAs among other metabolites.
• Rapidly broken down starch in the rumen leads to
the accumulation of SCFAs that leads to drop in pH
and metabolic consequences such as SARA and ARA
Mechanisms of starch utilisation
• Starch can be utilized at three levels in
ruminants;
– Rumen: breakdown by ruminal microbes
to SCFAs that are converted to glucose in
the liver
– Small Intestines: Starch here is acted
upon by pancreatic amylases to glucose
that is actively and passively taken into
portal circulation.
– Large intestines: Breakdown by microbial
amylases to produce SCFAs that have a
similar fate to those in the rumen.
Problem situations
• Rapid degradation of starches has
consequences on ruminant performance and
health.
• A dip in rumen pH below 6.0 leads to the
development of rumen acidosis that impairs
digestion, precipitates development of frothy
bloat, laminits, liver abscesses and
polioencephalomalicia.
• Overall impact on the profitability of beef and
dairy businesses.
Solutions
• Feeding cereals resistant to microbial
degradation in the forestomachs aka bypass
starch, undegradable starch or RRS.
• Mechanisms of increasing RRS are;
– Chemical treatment of grain using
• Sodium Hydroxide
• Formaldehyde
• Ammoniation
Either too expensive or
might have unforeseen
consequences on health
or animal or the laborer
– Grain treatment using weak organic acids;
• Lactic acid
• Malate
Research still at infancy to
prove efficacy at farm
level
– Tannins – secondary plant constituents suggested
to slow down ruminal starch degradation through
complex formation with starch
In Summary