Feed planning for brassica and forage crops

Brassica and forage crops require different management to grazed grass. Below, we share tips on measuring dry matter (DM) and calculating daily feed requirements.

Feed budgeting and planning can allow you to maximise the use of home-grown feeds and reduce the amount of bought-in feed. Assessing available feed also stops under or over allocation, which can improve efficiency and prevent waste.

When grazing brassica or forage crops, livestock must have access to hay, silage, or grass to promote saliva production and healthy rumen function. Straw is generally not recommended. Baled grass silage or hay should be 35% of total DM intake when feeding. Ensure this is accounted for in the feed budget so that all animals can access conserved forage.

Monitoring and reviewing your feed budget monthly will ensure nutrition and feed allowance is appropriate for livestock age, growth, ground conditions, shelter availability and stage of production. For example, heifers may require over 1 kg DM/animal/day additional allocation (or + 10–20% feed).   

Some of our tools include:

For accurate feed planning, it is essential to measure the DM yield of the crop.

This can easily be done by using a:

• 1 m square frame
• Seedbag
• Garden shears
• Scales

Several samples should be taken from each field, picking representative sampling points. The process is:

1. Place frame in the forage crop.
2. Use shears to cut each plant within the frame (about 10 cm from the ground).
3. Put the harvested crop in the bag.
4. Hook bag onto scales.
5. Record the crop weight per metre squared (kg/m²).
6. Calculate DM yield/ha:
   1. Multiply the fresh weight per m² by 10,000.
   2. Multiply by the expected crop DM percentage.

See our tables on cost and performance of livestock grazing brassica and forage crops.

For example: Kale from 1m² = 5 kg fresh weight x 10,000 = 50,000 kg fresh weight/ha Average kale dry matter = 16% 50,000 x 0.16 = 8,000 kg (8 t) DM/ha

Table 1. Steps to calculate your livestock and forage requirements

Notes: *Based on crop yields of 8 t DM/ha (0.8 kg DM or 5 kg fresh weight per m²) multiplied by 70% utilisation.

A well-designed feed out system should help to reduce environmental impact and ease management.

Things to consider:

• Grazing direction should be downhill so that any run-off gets captured by the standing crop
• Grazing duration and traffic should be managed using stocking density and moving troughs and feeders
• Provide maximum frontage (length) to the feed fence but a narrow strip of accessible feed, to allow all animals to feed at the same time (guidance is available at Red Tractor standards)
• Easily moveable electric feed fence will make management and crop allocation easier
• Place bales before winter to avoid driving over the crop and causing damage to the crop or soil
• Estimate supplementary feed requirements
• Infrastructure such as electric fencing, tracks, gateways, moveable water troughs and feeders
• Fence off watercourses and boggy areas to prevent damage and leaching
• Provide a well-drained, dry, accessible lying area with shelter to prevent animal heat loss
• Allow enough space for all animals to lie down at the same time, allocate 2 m² per head for cattle