MANUAL ON IMPROVED FEEDING OF DAIRY CATTLE BY ... - Gart

When estimating the dm intake of an animal it is assumed that it
receives an unlimited supply of roughage. This means that the animal has
permanent access to the fodder. After eating as much as it likes, there
should remain an edible left-over of about 10 % of the supplied forage.
It has been established that under those conditions a ruminant will eat
between 1.5 % and 2.5 % of its bodyweight in form of roughage. The
actual percentage depends heavily on the quality of the fodder which
is supplied. When an animal receives poor quality roughage its intake
is reduced. And since the fodder it eats contains only little nutrients,
the total intake of nutrients becomes extra low. Therefore good quality
roughage is the basis for a high milk production. In general we can say
that a cow with a bodyweight of 450 kg is able to eat approximately
between 7 – 11 kg dm roughage per day. However, it should be realized
that in order to achieve this amount, the intake of young, fresh grass
might easily reach over 60 kg per day. In case the farmer cuts and carries
the grass, he should supply about 70 kg fresh material per cow per day
to enable the animal to get fully satisfied.
On average we can work in our calculations with a dm intake out of
roughage of 2 % of the bodyweight.
The total dm intake, including concentrates, of a normal producing
dairy cow can be considered in the range of 8 – 13 kg dm per day.
However, a well developed, high producing cow, which is supplied
with good quality fodder and concentrates might even take in up to
18 kg dm per day.
6. ROUGHAGE (FODDER) AND CONCENTRATES
The difference between roughages or fodder and concentrates is highly
related to their feeding value. In general roughages have a rather low
feeding value and a high crude fibre percentage. Concentrates have a
high feeding value and are low in fibre. The main reason is that in case
of fodder the complete plant is used as a feed, including the leaves and
the stem. In concentrates only those parts of the plants are used which
contain a higher concentration of nutrients, like starch and sugar. These
are found particularly in seeds, tubers and sometimes in roots. Also
byproducts of seeds are concentrated feeds. In conclusion we can say
that:
Roughages are characterized by a higher fibre content, are bulky and
generally contain the vegetative portion of a plant or tree. The digestible
energy content is low and depends highly on the variety of the fodder
and the maturity stage at harvesting. For that reason a high variation in
feeding value can be observed.
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Manual on improved feeding of Dairy Cattle by Smallholder Farmers