nutrition 101 | management
The hippopotamus is an unselective bulk
feeder. It has a low metabolic rate and while
it lies in the water during the day, it degrades
the ingested feed, utilises what is necessary
and stores the rest of it as fat, which is
necessary for the lean winter and drought
months.
The hippo’s digestive strategy is similar
to that of the ruminant (buffalo and antelope
species), where both the pseudo rumen
and the rumen are cranial to the gastric
stomach, but it differs with regard to the
shape of the forestomach and the fact that
they can’t regurgitate the ingested grass
for it to be ruminated (chewed into a fine
paste) at a later stage. The hippopotamus
must grind the selected grass with its
premolars and molars into the smallest
particle possible before swallowing it. Saliva
aids the hippopotamus in swallowing the dry
food, which enters the pseudo rumen via the
oesophagus.
Figure 1 illustrates what the pseudo rumen
looks like and indicates the correct names
for the different parts thereof.
The smaller particles undergo further
degradation and fermentation by microbial
activityin thefluid-filledpseudo rumen.
Microbialactionandfermentation convert
thefibrouscomponentof theingesta
intovolatilefattyacids(VFAs). The VFAs,
namelyacetic,butyricandpropionic acid,
getabsorbedthroughthewalls of the
forestomach,whiletherestoffermented
ingestamakesitswayintothe gastric
stomachwherethelipidsand hydrolysable
carbohydratesgetenzymatically broken
downtotheirconstituentparts. The acidic
contentsofthegastricstomach breaks
proteinsintopeptidesandpoly peptides.
Thesenutrientsgetabsorbed into the body
in thesmallintestine.Waterand minerals get
absorbedin thecolon.
Thehippopotamus,unlikeother ungulates,
donothavea caecum(figure 2); the
smallintestineentersthecolon directly.
Furthermore,thelargeintestine is rather
short– it accountsforapproximately^1 / 10 of
thetotalintestinallength.
Thehippo’sGITrepresentsthe two
extremesoftheungulategut,where it has
oneofthemostcomplexforeguts but a
simpleandveryshorthindgut. >>Intake of dry food for an animal weighing
1 000kg ranges from 1% to 1.5% for male and
female animals, where a cow with calf will require
approximately 1.9% dry food (dry matter) on a
daily basis. In other words, a hippopotamus cow
requires approximately 15kg dry grass per day,
equating to approximately 16.5kg grass on
a 10% moisture basis.FOREGUT FERMENTER
Common hippopotamus (Hippopotamus amphibius).
Photo © Eric le Francais
Figure 2: Gastrointestinal tract of the hippo.
Illustration by Ronelle Oosthuizen