BRASSICASCrop planning and feed budgeting

Allister MoorheadSenior Agronomist from Agricom

Why use winter brassica ?

Maintenance grazing of large number of animals on relatively small areas (particularly ewes)

Providing large volumes of high quality feed for providing liveweight gain (mainly beef)

Crop planning and feed budgeting

Tips for estimating yield

Summer crop - General Guide Only (based on a 1.8m person)

Rape

<2 2 3 4 6 8 10 12

Foothigh

Calfhigh

Kneehigh

Knee - hiphigh

Rare

Leaf turnip Foothigh

Calfhigh

Kneehigh Undesirable

Yield (t/ha)

Leaf yield (t/ha)

Forearm Elbow Arms length

2 3 5-6

Tips for estimating yieldBulb yield (t/ha)

Leaf yield (t/ha)

Turnipbulb

Plant pop.(plants/m2) Tennis ball Softball Gum boot

10

20

30

1.2

2.4

3.6

3.2

6.4

9.6

6.4

12.8

N/A

Being aware of the impact of crop DM%

Crop dry matter (DM) percentage has huge impact on crop yield (kg DM/ha)

Example:

One quadrate of 1m2 = 10 kg fresh weight

Dry looking crop = 14% DM = 1.4kg DM/m2 = 14,000 kg DM/ha

Fresh looking crop = 12% DM = 1.2kg DM/m2 = 12,000 kg DM/ha

2% difference in DM% has around a 15% difference in crop dry mater yield

Crop planning

Having the ability to do this;

Adds value to your client

Makes you valuable to him

Sets you apart from many other reps

Provides you the opportunity to influence volumes

Knowing your Assumptions

We need specific information on;2. Potential Yield3. Crop utilisation4. Animal Intake5. Proportion of the diet from brassica6. Crop type

Assumption 1 - Crop yield

Crop yield is accurately assessed

Overestimation leads to inflated SR and reduced area and poor animal performance

Sensitivity analysis is recommended

Knowing your Assumptions

Assumption 2 - Crop Utilisation

Crop Utilisation

Rival turnip

Winfred forage brassica

Hunter forage brassica

85%

75%

70%

Leaf turnip forage components Fresh

Av. 181 g

75 % petiole25 % leaf

Dry matter

Av. 24 g

60 % petiole40 % leaf

LeafPetiole

DM 21%CP 30%WSC 19%NDF 15%ME 13.4 MJ

DM 11%CP 15%WSC 32%NDF 19%ME 13.3 MJ

Assumption 3 - Grazing Intake

Stock Intake(kg DM/hd/day)

Dairy

Lambs

Beef

16

1.5

8

Brassica intake aspercentage of total diet

33

100

80

Assumption 4 – Concurrent growth

No account made of concurrent growth

Can be significant (50kg DM/day)

Ignoring concurrent growth will tend to under-estimate stocking rate.

Assumption 5 – regrowth

When calculating SR or break size use yield on hand

When calculating sowing area use total yield

Yield used must reflect the expectation of regrowth

Example

A dairy farmer requires a crop of summer turnips to supplement his 320 cow dairy herd with summer turnips for 8 weeks beginning towards the end of January.

1. Predicted Yielding = 10,000 kg DM/ha

2. Utilisation = 85% DM

3. Intake = 5kg DM/Cow/day

4. We can base our workings on the above information we expect little if any growth during the grazing of the crop and we expect no regrowth

Order of working

1. Identify supply (feed available) - Yield x utilisation

10,000 kg DM/ha x 85% utilisation = 8,500 kg DM/ha available

2. Identify demand – intake/day x number of animals

5kg head/day x 320 head = 1600 kg DM/day

Order of working

3. Find out what one hectare will graze = Available yield / herds daily requirement

8500 kg DM/ha / 1600 kg DM/day = 5.3 days grazing per hectare

56 days (8 wks) / 5.3 days = 10.6 ha of turnips are requiredto feed 320 cows 5 kg each per day for 8 weeks

Summary

Remember your tips for estimating yields (or Historic info)

Remember the impact of dry matter percentage on Yield

When discussing feed planning know your assumptions

Have an understanding of animal requirement figures

Understand what are realistic utilisations and the impact of utilisation on animal performance

Knowing your Assumptions