Grazing of fodder crops should occur at phases in the growth cycle when the plants are the most nutritious. This can be challenging due to the fast growing nature of some forage crops and a grazing strategy should be developed to match feed demand with supply.
A well considered grazing strategy is important in maximising the productive potential of a fodder crop. Fodder crops have the potential to produce large volumes of high quality feed and if not carefully managed, this can easily become rank and lose nutritional value.
Grazing strategies include the use of:
- Rotational grazing
- Continuous grazing
- A combination of the above
Describes the practice of rotating livestock through a series of paddocks, where by the time the last paddock in the series has been grazed, the first has been rested allowing sufficient pasture growth for the paddock grazing sequence to commence again. Rotational grazing strategies are most effective when conducted at a high stocking rate or stock density and livestock should be moved before the feed supply in the grazed paddock is totally depleted. If livestock are allowed access to forage crops when hungry or empty, animal health issues can arise.
Crops should be stocked conservatively to allow plants to recover such that grazing can be maintained over the crops growing period.
Supplements should be fed with some forage crops to stimulate rumen function and compensate for nutritional deficiencies.
Health and welfare
There are a number of potential health and welfare issues associated with grazing forage crops. Some of these are associated with particular plant toxins eg the propensity for sorghum to produce hydrogen cyanide (HCN) during early growth and when moisture stressed. Others are due to physiological reactions within livestock, such as acidosis, which occur when ruminants are suddenly exposed to large volumes of high quality feed.
Producers should consider the following health and welfare strategies when grazing forage crops:
- Livestock should be introduced gradually to forage crops to allow the rumen to adjust to the new feed and avoid giving hungry livestock sudden access to forage crops.
- Roughage should be made available, usually as hay, to assist with rumen function and slow the passage of highly digestible feed through the rumen.
- Water should be freely available as limited water can also limit feed intake.
- In some circumstance, mineral supplements may be required to prevent metabolic or nutritional disorders.
Producers should familiarise themselves with the potential animal health issues associate with each forage crop and this should be considered in selecting a crop that best suits the particular enterprise circumstances.