Back Setting up for next spring

Date: 12 May 2017

This season has to have been one of the more challenging seasons for growing and harvesting maize silage.  However, most of the crops have been harvested and are now being fed to dairy cows. The milking season is nearly over on many farms and farmers are beginning to plan for this coming calving. Maize silage is the perfect late lactation/early winter feed to enable farmers to achieve BCS and pasture targets this coming sprin

Wintering on maize silage

Despite the harvest being late, nearly all maize silage crops are now harvested and are being fed to late lactation or dry cows. Maize silage is an ideal feed for the late lactation and winter period. The high starch content of maize silage makes it an ideal feed for putting weight on cows during the late autumn and winter months. The fibre part of the plant makes it ideal for extending out the round length and managing pasture during the low growing months of winter. Having a feed pad, enables cows to be stood off and fed maize silage thereby preventing damage to paddocks which may occur during wet periods.

Body Condition

Getting cow body weight back on before the next lactation makes good economic sense. There is a robust, scientifically proven relationship between cow condition score (CS) at calving and milk production during the subsequent lactation, cow fertility and dairy farm profitability. Simply stated, cows that calve at CS 5 produce 10-15 kg more milksolids and cycle 7-10 days sooner than cows that calve at CS 4. To achieve this, aim to have mature cows in CS 5.0 and 1st and 2nd calvers in CS 5.5 at calving. Maize silage is an excellent feed for putting weight on cows and is up to 20% more efficient at doing so than a feed like autumn saved pasture.

Building pasture cover

There are significant benefits of feeding maize silage in the autumn. Because it is a forage, feeding maize silage results in more pasture left in the paddock making it an ideal feed to build up pasture cover levels. The net result is that it is a lot easier to achieve target pasture covers for the beginning of calving. 

Standing cows off pasture

Winter pugging can have a significant negative impact on pasture production.  The level of pasture growth reduction will be determined by the level of pugging.  On some soils, pugging may result in a reduction in pasture growth by around 40%.  Maize silage, fed on a feed pad, enables farmers to feed their cows off paddock and therefore reduce the risk of pasture damage caused by wet soils


Things to be aware of

Nutritionally, maize silage is an excellent complement to high quality pasture however there are a few things to be aware of when feeding it.

1. Watch dietary protein levels. Maize silage is a low crude protein feedstuff. Maize silage is around 8% crude protein which is low compared to pasture which typically contains 16-24% protein in the autumn and winter. Cows require at least 14% crude protein in late lactation and 12% crude protein to achieve good liveweight gains when they are dry. For this reason, maize silage should make up no more than 50% of the diet for milkers and 60% of the diet for dry cows. Maize silage feeding rates will need to be further reduced if you are feeding other lower crude protein feedstuffs (e.g. potatoes, kiwifruit, apple pomace, poor quality pasture silage or even palm kernel).

2. Introduce maize silage gradually. Acidosis (also known as grain overload) occurs when excessive lactic acid builds up in the rumen due to the rapid fermentation of too much starch or readily available sugar in the absence of adequate amounts of fibre. Acidosis most commonly occurs when cows are fed too much of a high starch (e.g. grain or tapioca) or high readily available sugar (e.g. kiwifruit or molasses) feed. Because maize silage is a mix of grain and high quality fibre and maize starch is more slowly degraded by the rumen bacteria than other types of grain, acidosis is rare with maize silage. It does however occur occasionally when feeding large amounts of maize silage especially if the maize has been chopped very finely (<8 mm theoretical chop length) and is introduced into the diet very quickly. To reduce the risk of acidosis introduce maize silage slowly (increasing at around 1 kgDM every other day) and make sure that the herd, or a significant portion of the herd has access to the silage to avoid individual animals gorging themselves.

3. Check mineral levels. Mineral supplementation may be required if you are feeding a significant amount of the diet as maize silage. Use the following table as a guideline only. If you are feeding more than 40% of the diet as maize silage, contact your farm advisor, veterinarian or Pioneer Forage Specialist for a farm specific mineral recommendation.



grams per cow per day



(provides calcium )

Magnesium oxide (provides magnesium)


(provides sodium)

Late lactation




Dry cows




4. Watch for mould. Because it contains high levels of readily available carbohydrate, maize silage is more prone to mould than other types of silage. If your stack is well compacted, covered and sealed, mould growth should be minimal. However if your stack has not been well compacted or you are one of a significant number of farmers who has “never got around” to sealing your stack or weighing down the cover with tyres that are touching, you may have some patches of mould especially near the surface. There are a range of moulds and although many are relatively harmless, as a safety precaution, never feed mouldy silage to your herd and in particular to pregnant or young animals.


In summary, maize silage is an excellent feed for putting weight onto cows. Use your maize silage to increase body score so you maximise milksolids production next season.


Ian Williams

Forage and Farm System Specialist