December 28, 2011
Brassica forage crops may lessen Welsh feeding costs
By growing brassica forage crops in 2012, livestock farmers of Wales could save more feed supplies and lessen overall feeding costs.
According to independent grassland expert, Charlie Morgan, brassicas - including kale, fodder beet, swedes and stubble turnips - can fill short-term summer grazing gaps or be a means of out-wintering stock.
And because these crops are grazed in the field, they are usually cheaper to grow per unit of dry matter (DM) than grass silage.
Swedes and fodder beet are up to 18% DM and all brassica crops have a digestibility of over 80% making them more digestible than grass.
The key to getting the best from a crop is to always test the soil before sowing, he advised.
He said, "It is essential to test soil nutrient levels and pH before sowing. All too often, we plant crops without knowing what is in the soil. When the cost of fuel and fertiliser was cheaper, we could perhaps get away with it. But that's not the case any longer. Soil testing will tell us exactly what a crop needs before we plant it.'' An advantage of a brassica crop is that it will grow on poor ground."
The pH range needs to be between 5.6 to 6.5.
Morgan stressed that the environmental implications of growing the crop must be carefully considered.
"If there is run off, the land loses nutrients and soils that can't afford to be lost,'' he said.
He said crop choice and field selection must be appropriate for the system.
And he said one of the best sites for a brassica crop is a field that needs reseeding and ideally the soil should be free draining.
Hedges and tree cover will provide shelter otherwise animal performance can be affected, he warned.
Most nutritionists would recommend that brassicas should account for no more than 50% of an animal's diet but Morgan reckons this can be upped to 70%.
"Supplementing the diet with ad-lib fibre including straw, silage, hay or old grass, to provide the so-called 'scratch factor' in the rumen, will stop the protein in the brassicas from being excreted," he said. "And because the crops are deficient in trace elements, stock should be bolused or given access to mineral buckets before grazing."
He said the key to utilising the crop successfully is to strip graze using an electric fence.
This maximises crop utilisation and minimises wastage. "It's no good having a 15 acre field and turning 100 lambs onto it to roam freely,'' said Morgan. "They will eat the leaf first which contains the protein and will not capture the energy in the stem and the bulb which is key to growth rates.''