Summer Beef Series: Impact of silage quality on dairy calf-to-beef

Summer Beef Series is in conjunction with Teagasc’s DairyBeef 500 campaign

If someone was to list the main reasons for low levels of profit in a dairy-beef system, the list would consist of a debate about beef sire genetics, cow type, calf price, and the cost of the main inputs such as meal, fertiliser and milk replacer.

One area that is often grossly overlooked is the impact silage quality has on the overall profitability of dairy calf-to-beef enterprises.

This is surprising as grass silage is a core component of the animal’s life at some critical and costly periods such as the finishing phase when poor-quality silage can double the amount of meal required for the final 70-100 days of feeding.

When meal prices over the last winter hit north of €450/t, good-quality silage came into its own. Taking the winter we have had, weanlings could have spent four to five months indoors on silage while finishing or store cattle could have spent a similar length of time on silage also.

What farmers need to remember is, silage that will maintain a dry cow for the winter will not maintain a weanling or fatten a store bullock in a shed without significant concentrate input.

When aiming to make top quality silage farmers must understand the factors that affect quality.

Bellow is a graph showcasing the effect of cutting date on DMD %

At this stage of the year, fertiliser is spread a while for first cut and really the only decision to be made on first-cut silage is when to cut the crop.

The weather in the first half of May was especially bad with constant downpours particularly in the western half of the country so chances to take an early cut were limited.

If we want to assess how much is early cut good-quality silage worth to a farm, we must compare the value of the daily weight gain on good quality silage with poor quality silage and adjust for meal input.

For this case study we will assume a store bullock has to gain 120kg liveweight indoors on silage and meal.

For a farmer finishing 100 cattle over the winter, this would equate to a meal bill of an extra €39,000 to achieve 0.83kg/day on top quality mid-May cut silage versus poor quality late June silage.

Good preservation

Grass sugars are converted to acid during the anaerobic fermentation process. This acid preserves feed value of the crop in the sealed pit.

The target sugar content to ensure good fermentation is 3% or higher. This can be tested using a refractometer. Optimum conditions for high sugars are ryegrass swards, dry sunny weather, cool nights and mowing in the afternoon when levels have built up. Very leafy grass has lower sugars. Wilting will help to increase DM content.

Anaerobic conditions are essential for initial fermentation and to prevent subsequent spoilage. Fill the silo quickly and roll well to exclude air. Chop length of 1.0-1.2cm promotes good compaction. Cover with 2×0.125 mm polythene sheets. Use vertical sheets along silo walls. Check for three to four days to ensure seal remains intact as the pit settles. Prevent bird damage.

Buffering capacity measures the resistance to a drop in pH. Crops with high buffering capacity may have a poor initial fermentation. High nitrate in grass increases buffering capacity. This can be checked using nitrate test strips.

However, nitrates are of secondary importance to sugar levels. Grass will ensile correctly with up to 800ppm nitrate provided sugars are adequate. Wilting the crop to >28% DM helps to overcome effects of high nitrate.

Impact of silage quality

While every farmer must ensure they have adequate fodder supplies this winter – especially given reserves are depleted following the long winter just gone by – silage quality must be to the fore of every dairy-beef farmers mind.

Delaying cutting to increase yield is a false economy that can turn calf-to-beef profits down into negative territory.

By Alan Dillon, DairyBeef500 campaign manager