Feed planning for brassica and forage crops

Brassica and forage crops require different management to grazed grass. See our tips on measuring DM and calculating daily feed requirements.

Back to: Grazed brassica and forage crops: feeding and management

Why is feed planning important?

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:

AHDB grass and supplementation budget planner

Feed budget and rotation plan for cattle

How to measure forage crop yield

Measuring dry matter

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

Row

Description

Example based on a 270 kg weanling requiring 8 kg DM/day

Your livestock and forage requirements

1

Livestock total daily intake (assume DM requirement of 3% of liveweight)

8 kg DM/day

 

2

Percentage of crop in the diet

70%

 

3

Crop daily requirement  (row 1 multiplied by row 2, divided by 100)

5.6 kg DM

 

4

Number of livestock

25

 

5

Daily crop requirement (row 3 multiplied by row 4)

140 kg DM

 

6

Estimated crop DM yield/m2*

0.56 kg DM/m2

 

7

Total daily grazing area required (row 5 divided by row 6)

250 m2 of brassica

 

8

Length of feed face

125 m

 

9

Fence to be moved (row 7 divided by row 8)

2 m/day

 

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.

Cost and performance of livestock grazing brassica and forage crops

Field design

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

Example plan for establishing a feed face

Useful links

Use the feed and forage calculator

Using brassicas for Better Returns manual

Feeding the ewe

Feeding suckler cows and calves

Feeding growing and finishing cattle

Making grass silage for better returns

If you would like to order a hard copy of the following resources, please contact publications@ahdb.org.uk or call 0247 799 0069:

  • Using brassicas for Better Returns
  • Feeding the ewe
  • Feeding suckler cows and calves
  • Feeding growing and finishing cattle
  • Making grass silage for better returns
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