Ignorance about feed often results in animals being fed too much or too little, with economic losses, says Elsenburg’s CJC Muller.
Feed for dairy cows is divided into roughage and concentrate. This week we look at roughage:
Hay from legume plants
Lucerne is the best-known legume hay. Highly palatable, it’s usually beneficial in nearly all rations. It has high protein levels, but is relatively poor in energy.
There is no restriction on the level of inclusion. Because of its high calcium content, though, you should avoid using it on dry cows that are prone to milk fever.
Pea hay is mostly of a poorer quality than lucerne hay. It’s utilised in the same way, but if the hay is stringy, it should be milled to increase intake.
Grain and grass hays
These have a lower protein and calcium level than legume hay. In lactating cows the levels of inclusion is usually limited because of this.
Grazing is normally the cheapest source of roughage for dairy cows. Factors limiting production are mainly energy content and moisture content of crops. The protein content of rye grass clover is usually high. Kikuyu has a low calcium level. Other pastures have high levels of potassium that could increase the incidence of milk fever.
The cheapest method of storing roughage. Maize is mainly used, although good quality silage can also be made from most grass types and legumes.
The crude protein level in silage is often higher than that of hay. It is excellent for young animals older than nine months. There is no limit to its inclusion in dairy cow rations.
Mouldy silage often contains fungi with dangerous toxins and should not be fed to animals.
What about straw?
Straw consists of the stalks and leaves of crops that remain once the seed has been threshed out. Oat straw is probably the most valuable, followed by barley.
The relatively low nutritional value limits its inclusion level. Small grain straw should not be used in rations for dairy cows. With the necessary supplementation, straw can be used to a limited extent in the feeding of replacement heifers.
Small grain straw is often upgraded by treating it in an oven or in a stack with ammonia.
This improves the energy and protein content, as well as the palatability.
There is seldom a need to mill ammoniated straw. This type of straw should not make up more than 40% of the ration. Supplement with phosphorus, magnesium, zinc, cobalt, selenium and copper, as well as vitamins A and E.
Source: Elsenburg infopak compiled for the Western Cape department of agriculture.