Late cut silage and low protein levels

SILAGE that has been harvested late in the season can have very low levels of protein and where such silage has been analysed confirming low crude protein levels there may be concerns regarding the ability of the silage to meet the requirements of cattle over the winter period.

Harvesting of silage was delayed in many cases this autumn and the occurrence of low crude protein levels in silage may be significant.

Sufficient protein is required to provide a source of nitrogen to rumen bacteria to enable the rumen to function.

If there is not sufficient protein in the diet proper digestion will not take. Rumen fermentation will slow down and intake will reduce which will impact animal performance.

The only way to ascertain the crude protein content of silage is to have it analysed.

However silage analysis results are often limited to a minimum 8% CP i.e. it cannot be measured below this level. Caution should be exercised when crude protein values are reported this low as they may be lower in reality.

Where very low levels of protein are recorded a suitable supplement should be used to bring the diet up to required levels for the type of stock being fed.

The minimum crude protein levels in the total diet (kg DM) for different classes of stock to maintain rumen function are - dry suckler cow 9%, lactating suckler cow 11%, newly weaned suckler calf 14%, and store animals 11%.

Low protein silage has been associated with rumen impaction which can result in fatalities of suckler cows on farms. Check dung for consistency.

If dung is very solid and dry with slow passage rates, there may be an issue with digestion of fibre due to inadequate protein.

If insufficient crude protein is available the cow will be forced to mobilise lean tissue rather than fat, and if the deficiency is prolonged it could result in poor calves born from thin, weak cows.

There are a number of options to address the issue where it occurs.

Suitable feedstuffs including beans, distillers grains and maize gluten feed can be fed between 1 and 2 kg/ head/ day depending on the severity of the deficiency.

For example maize distillers would cost between €0.22 and €0.33 per head per day. Soya bean meal at 0.5-.75 kg/head a day can be fed also.

This would cost between €0.17 and €0.26 per cow per day. Where commercial rations are used a minimum of 20% CP should be targeted to reduce the quantity to be fed. At a feeding rate of 1.5 to 2 kg day it would cost €0.37 to €0.56 per cow per day.