While farmers will know how much silage it takes to feed an animal each day, visually, putting actual figures on it may be more difficult for those not feeding through a diet feeder.

As a simple rule of thumb, cattle will eat about 2% of their bodyweight in dry matter (DM) each day. Therefore a 500kg animal will eat 10kg DM each day.

Within this, there are many variables that will alter the intake of an animal on a fresh weight basis. Some of these include; silage quality and silage DM, concentrate feed levels, availability of fresh clean water, freshness of the feed and ambient temperature (cattle will eat more if colder eg outwintered animals can eat up to 25% more DM/day).

Silage DM

The DM of a silage is the percentage of feed, left in a kg of silage, once all the moisture is removed. Typically, silages range from the mid-20s to mid-30s in terms of DM percentages. Baled silage is typically drier than pit silage.

The DM can have a big effect on the overall intake of silage required each day.

A 500kg animal, on a silage only diet, will consume 40kg freshweight of a 25%DM silage while it could be as low as 29kg freshweight if the silage is much drier, at 35%DM.

To put it another way, if we only fed 29kg of the 25%DM silage to the same bullock, we would be underfeeding him by almost 30% each day.

Therefore to calculate daily, and whole winter requirements it is important to know the DM of your silage.

Demo farm

On the Thrive Demo Farm the 145 yearling cattle are currently averaging just over 310kg liveweight. That means their DM intake each day is 6.2kg (2% of 310kg).

Alongside their silage, they are also receiving 2kg fresh weight of a 16% protein ration which we need to allow for when calculating their daily diet. Concentrate is typically around 86%DM meaning that the 2kg fresh weight translates to 1.7kgDM.

Therefore the silage requirement per day is reduced (6.2kgDM – 1.7kgDM = 4.5kgDM/day).

The average DM of the baled silage in the yard is 27% meaning they need almost 17kg of silage fresh weight to meet their daily needs (4.5kgDM ÷ 0.27 = 16.66kg).

The average dry matter of the silage on farm is 27%, however this ranges from 23% up to 31%. When feeding wetter silage, more kg fresh weight must be fed.

Diet feeder

The cattle on farm are fed each day with a diet feeder. This means each mix needs to contain:

  • 290kg of concentrate.
  • 2,465kg of silage.

    • The bales on farm average out at 700kg (again this can vary depending on the baler, chopped or unchopped, how leafy or stemmy the grass is, weather conditions at harvest and how much of a wilt the crop received before baling.

    For this reason it is worth weighing a few bales if you have a cattle weighing platform on farm).

    In this case, we need to feed 3.5 bales of silage each day (2,465kg ÷ 700kg = 3.5 bales).

    On this farm, the hope is to have stock out in early March, therefore we are currently at the mid-point of the winter. We can therefore use their current weight as an average for the whole winter to calculate total silage requirements.

    In terms of kilos, each animal is eating just shy of 2,000kg fresh weight silage over the 115-day winter period.

    3.5 bales/day × 115 days housed = 403 bales of silage which works out at 2.8 bales/head or 0.75 bales/animal/month. Obviously you don’t want to run out of silage or run the system this tight. A minimum buffer of three weeks feeding should be included in the calculation.