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

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Manual on improved feeding of Dairy Cattle by Smallholder Farmers
Some examples of the differences in the percentage of crude protein
in some feeds:
Feed Crude Protein %
Low Straw 1 - 2
Hay 6 - 7
Medium Green fodder 3 - 12
Legume - hay 13 - 15
High Oilseed cakes 30 - 45
Not all the proteins present in a feed can be utilized by an animal. Part of
it will appear undigested in the faeces. The part of the crude protein that
is digested by the animal is called the Digestible Crude Protein (dcp), see
chapter V.
4.2 Carbohydrates
In the group of carbohydrates we can distinguish 2 groups of chemical
compounds:
Soluble Carbohydrates
The soluble carbohydrates consist of starch and sugars. These nutrients
can be digested directly by the animals. The animals are able to utilize
them well and their digestibility is high. These form the major source
of energy for the animals. If more energy is provided than immediately
needed, the surplus is stored as body fat.
Crude Fibre
This is the fibrous material in the plant. It is in particular found in the
stem, where it provides structure to the plant and gives the plant its
shape. Crude fibre (cf) is not easily digested by the animals. It consists of
cellulose, hemi-cellulose and lignin. The bacteria in the rumen of the cow
and other ruminants assist the animals in the digestion of these fibres.
The digestibility of fibres is low. Ruminants always require a considerable
amount of crude fibre in their ration for a proper functioning of the
rumen. However, a very high content of crude fibre reduces the feed
intake of the animal.
Functions of carbohydrates
- A ready source of energy (necessary to maintain the body and for
activities, like walking, grazing, milk production, etc.)
- Maintain a constant body temperature
- Important to maintain the level of blood sugar
- Excess of carbohydrates are stored as reserve energy in form of
body fat
- Milk sugar (lactose) gives sweetness to milk and is used by bacteria
to turn milk sour
- Essential for the growth and multiplication of micro-organisms in the
rumen
- Helps in the absorption of Ca (calcium) and P (phosphorus)