Managing silage quality and concentrate supplementation

On beef farms, the quality of grass silage is a critical aspect to the winter feeding period. It determines the potential need for additional concentrates to ensure animal performance is maintained over the housing period and weight gain targets are achieved.

This is especially important on calf-to-beef systems, where a farm is dealing with spring-born animals being housed during their first winter.

Their weight gain at this stage can determine their performance over the second grazing season and ultimately have an effect on their finishing weight.

Why complete a silage analysis?

Often heard on farms is the statement claiming, ‘that looks like great silage, it can’t be that bad of feeding value’ – however unfortunately, visual assessment alone is not sufficient to determine true silage quality.

In order to find out the true nutritional value, laboratory testing is required.

The results will provide an analysis of dry matter (DM), dry matter digestibility (DMD), metabolisable energy (ME), UFV, UFL, pH, crude protein alongside other relevant information.

According to Teagasc, it is important that the correct method is applied to avoid inaccurate results when taking silage samples for analysis.

Correct silage sampling procedure:

  • Use a long core sampler;
  • Three to five samples should be taken from well-spaced points or between diagonals on the pit surface;
  • Core to within 0.5m of the pit floor;
  • Discard the top five inches of each core before mixing into a composite sample;
  • Alternatively, samples can be taken from an open pit face in a ‘W’ shaped pattern, with up to nine hand grabs being sufficient;
  • Seal the samples in bag, excluding air;
  • If testing bales, a number of samples are required from each batch in order to get a representative sample and test batches separately;
  • Use only Forage Analysis Assurance Group (FAA) accredited lab.

Matching silage quality and concentrate feeding

From these results, the decisions can then be made on the requirement of concentrates. Calf-to-beef farms in particular require high quality silage (above 72 DMD).

If silage quality is below optimal levels, these animals may require further meal supplementation to improve energy and protein density in their diets. This is especially important for growing and finishing animals where there will be varying requirements for energy and protein.

The table below highlights how the DMD of silage will influence the level of concentrates necessary in order to achieve daily liveweight gain (ADG) targets.

Data source: Teagasc

It is important to note that both energy and protein can be limiting factors within a beef animal’s diet.

In terms of rations, weanlings have an energy requirement of >0.94UFL, while >0.92UFV is necessary for finishing animals’ rations.

A crude protein content of 14-16% is desirable in weanling rations, meanwhile 11-14% of crude protein is needed for finishing rations, according to Teagasc.

For further information and advice on balancing silage and concentrate requirements, please click here