Are you cudding me? - The sign in the cubicle house that something's not right 

Silage which is too acidic can lead to poor intake and digestive upsets, writes farm vet Hazell Mullins.
Are you cudding me? - The sign in the cubicle house that something's not right 

Silage which is too acidic can lead to poor intake and digestive upsets, writes farm vet Hazell Mullins.

Last Friday marked the always anticipated annual Tirlán Glenville’s winter open day. It is always a day that I like to attend to both meet vendors and, of course, to enjoy tea and cake with Glenville’s own Francis and Eamon Sweeney and James O'Callaghan. 

Eamon Sweeney reminded me the week previously not to forget to drop in silage samples for testing on the day, and was I glad that he did, as the results were eye-opening.

We never tested last year for some reason or another, which was a huge gamble on the farm as the health of the cow can be hugely affected by the silage she eats.

Taking the samples correctly is crucial to getting an accurate result, as with all diagnostics labs can only do their best with the samples we provide. For pit silage, it is important to sample in an imaginary 'W' formation across the front of the pit, taking a small sample at each point of the W. 

When it comes to bales make sure to open the bale out and try to take a sample from each layer. Mix each fresh small sample into a full airtight bag for posting; Monday or Tuesday is ideal to post as the fresher the sample arrives again the more accurate the result.

Each cut of silage is ideally tested if access if possible; trying to separate bales into different is a good way of knowing what is suitable for certain types of cattle. 

We made a mistake with testing our first cut silage, which isn’t opened yet - the sample wasn’t taken in a 'W' shape because of this, and only a wet section at the front was submitted, giving very skewed results, especially when it came to the dry matter content which should be between 24-28% with ours testing a low 22%.

We will have to submit another sample when the pit is open correctly, we will also send samples of our bales away too, knowledge is power after all.

The term dry matter digestibility (DMD) is used regularly when it comes to silage quality; it refers to the percentage of the silage matter that is utilised by the cow for energy. 

Teagasc has very useful tables available on their website ( that relate the DMD to concentrate supplementation for different cattle categories. 

We were very happy with our second Cut DMD of 72%, and we are currently feeding this to our milking cows before drying off with 4kg of concentrates daily to sustain milk production. Our first cut was lower at 69% DMD, which will be ideal for dry cow feeding during the winter as it will provide ample energy for their lower energy demands and help to combat increases in body condition score.

A vet's instincts

Since I began “cubicle duty”, as I call it, I have noticed cud balls (semi-digested food) at the front of about 10-15% of the cubicles. With my vet's nose on, it all makes sense now, as a major issue with our silage is poor preservation and excess acidity. 

There has been an increase in general of “cudding” this year on farms due to high acidic silage, perhaps due to the weather pattern we had this year. A very long wet spring followed by drought conditions and excess nitrogen in the grass may have led to this acidic silage. 

Silage should have a pH of between 4-4.2 pH, and our silage was 3.8 pH which has led to poor intakes and caused the rumen of some cows to become too acidic, leading to digestive upsets in the form of these cud balls.

For next year, we have been advised to sample the grass before mowing to check nitrogen levels before cutting. If the test stick reveals that nitrogen levels are too high grass we will let the grass grow longer before cutting or allow it to wilt for an extra day to reduce the nitrogen content and prevent this acidic silage.

By adding chopped straw, haylage or baled silage with a high fibre/dry matter content to counteract acidic silage as it acts as a fibre buffer in the rumen. We are also going to move to a more fibre-dense concentrate for the milking cows and dry stock.

The protein levels of ration will be lowered also due to our silage crude protein levels being high at 15% when the target is 12-14%; again, this could be linked to nitrogen levels. 

We also started to feed baled silage as a buffer feed, which has dramatically reduced the amount of cud balls present in the shed. We plan on feeding minerals with added yeast to help rumen health in the dry cows pre-calving to help with the current silage situation. 

If you are noticing these cud balls on the cubicles, consult with your vet and nutritional advisor for advice.

Further analysis

Our silage discovery journey is far from over, the next step is to send samples for mineral results to assess the risks for milk fever and other mineral deficiencies. 

A silage fed to dry cows should contain less than 2.2% potassium (K) to ensure milk fever prevention. High K silage acts as a blocker for magnesium uptake in the rumen, which has a knock-on effect on the calcium metabolism. 

If the amount of K is known early, measures can be taken to ensure magnesium levels are kept optimal with the addition of Magnesium salts, for example. 

For every milk fever clinical case, approximately another five sub-clinical cases are lurking under the surface. Knowing silage K levels can make a huge difference in milk-fever prevention on farms. 

Copper-blocking minerals such as Molybdenum, Sulphur and Iron should also be assessed and appropriate supplementation given to counteract their action.

Next weekend is a busy one with both the Veterinary Ireland President's Dinner in Mullingar and The Dairy Women conference in Kildare. My two main passions combined for an amazing weekend of knowledge transfer, and meeting colleagues and friends. 

This is the second year of The Dairy Women conference and the line-up looks so inspiring, as a girl growing up on the farm I would have never imagined a time when there would be a conference dedicated to women in dairy, it’s an incredible step in the right direction.

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Karen Walsh

Karen Walsh

Law of the Land


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