By Debbie James

Assessing silage stocks on a dry matter (DM) basis and using the same technique to cost bought-in feeds can be a reliable and cost effective approach for making up forage shortfalls.

Winter fodder stocks are generally good on Welsh farms this year, in both quantity and quality, but there are deficits in some regions that experienced very dry conditions.

For these, feed budgeting is essential, says independent ruminant nutritionist Hefin Richards

“It is not difficult or time consuming – establish what you have got in the clamp, work out if you have enough for the different stock groups. If you understand what you have and what you need you can budget for these shortfalls and work out the most cost effective approach to dealing with them,’’ he says.

An important first step to calculating purchased feed requirements is to accurately assess forage stocks in terms of tonnes of DM.

This means accurately measuring clamps or weighing bales and analysing their quality.

The big variable in clamp silage is density, Mr Richards points out, with DM, chop length and compaction all having an influence.

“Don’t assume that all clamp silage has a density of 800kg per cubic metre or you could find yourself running out of forage,’’ he warns.

A good estimate of density can be derived from the silage DM and clamp height.

But silage density and volume alone don’t give an accurate assessment of the feed available – determining the DM content is crucial because an animal’s feed intake is limited to the volume of DM it can consume.

“At 25 per cent DM, a dairy cow would need to eat 48kg of forage DM to meet her required daily intake of 12kg but at 40 per cent she would only need to eat 30kg,’’ says Mr Richards. “The wetter the silage the more she needs to eat to meet her dry matter DM needs.’’

DM intake requirements vary according to an animal’s weight, lactation status and stage of growth.

A milking cow will typically have a DM intake of 3.5 per cent of her bodyweight but a replacement heifer around 2.5-3 per cent.

When the amount of DM available has been established and matched to the number of animals it needs to feed, any deficits can be calculated.

Options for filling DM gaps typically include buying silage and other forages but there are alternatives, which should be costed on a DM basis.

“The freshweight cost might look attractive but the DM percentage varies according to the product,’’ Mr Richards explains.

“For instance, dry grain has a high DM content and fodder beet low and while potatoes can do a great job as a forage extender they are 80 per cent water, so in each case the product should be costed according to the amount of DM it can provide.

“Molasses is a relatively high DM product – 65-75 per cent – and the world is awash with sugar so current prices are more attractive than usual.’’

High protein molasses-based liquids are useful for balancing higher levels of straw, but are not generally suitable for dry cows due to their potassium content.

There is significant scope for feeding straw and hay to dry cows and growing animals, and in the milking cow ration too.

In dairy systems which feed moderate volumes of concentrates and have a small forage shortfall, Mr Richards recommends feeding more concentrates to displace silage as they can be paid for as they are used.

Another option is to reformulate blends to incorporate 2-3kg of a fibrous product such as soya hulls, palm kernel, lucerne pellets and nutritionally improve straw (NIS) or feeding straight cereals, he adds. “It is cheaper to feed 2-4kg of oats than to buy in maize silage.’’

In high yielding herds where concentrates are fed at a high rate, Mr Richards recommends feeding more digestible fibre and straights if silage inputs need to be reduced.

“Feeding 1.5kg of straw and 1.5kg of blend provides 2.6kg of dry matter which is equivalent to 9kg of silage at 30 per cent dry matter.

“If you can make subtle changes early in the year it is better than being forced to make drastic changes later if your silage runs out. If also gives the flexibility to update the ration if you find yourself in a better forage position than anticipated.’’

For youngstock, Mr Richards recommends straw or hay-based diets together with 4kg of a moderate energy 20 per cent protein mineralised blend or compound.

“Youngstock will grow 0.8kg a day comfortably on this and it is a very consistent and reliable way of saving silage.’’