Grazing Systems

GRAZING

Grazing refers to a system of allowing livestock to roam and feed on grasses growing in a pasture.

SYSTEMS OF GRAZING

1. Continuous Grazing: An extensive system where livestock are left indefinitely in an open pasture. It results in over-grazing and under-grazing leading to the uneven growth of grasses, bare patches and erosion. Pests and diseases also build up in grasses.

2. Rotational Grazing: An extensive system where the pasture is divided into (usually six) smaller holdings called paddocks and animals are allowed to spend 4-6 days in each. This rests each paddock for about 3-4 weeks. It prevents overgrazing and under-grazing and their effects and allows certain paddocks to be used for special purposes like breeding. Fresh dung (which kills the grass under it) is more evenly spread, reducing bare patches.

3. Strip Grazing: An intensive form of rotational grazing where each paddock is divided into strips by electrical fencing. Livestock remains within each strip for 1-2 days. This improves the rotational grazing system.

4. Zero Grazing: An intensive system where pasture grasses are cut and taken to animals in their pens. It is done where land is limited. There is an additional cost of harvesting.

Activity: Draw diagrams to illustrate each system and their advantages/disadvantages in your books.

CONSERVTION OF GRASSES IN ZERO GRAZING

There are three ways of preserving the grass for use at a later time:

1. As hay: Grass is cut before it flowers and matures and left in the sun to dry until it loses 80 % of its moisture so as to prevent bacterial and fungal attack. Standing hay is forage left standing in the field.

2. As silage: Grass is cut into short pieces, compacted, stored and covered in pit or tower silos so that air is excluded as much as possible. Where the sugar content of the grass is low molasses, enzymes, bacterial cultures and/or acids (a mixture of hydrochloric and sulphuric acid) is/are added to encourage fermentation of the grass. The temperature rises due to respiration, stopping the fermentation process. It is affected by stage of maturity, amount of moisture extent of air exclusion and the extent to which temperature rises.

3. As artificially dried grass: Grass is placed in a drying tray and a blast of hot air is passed over it.