Benefits of longer chop lengths

Fashion in agriculture – this seasons overalls clashing with last years wellies – what is she thinking? Fashions come and go and longer chop length seems to becoming fashionable again in some nightclubs….  I mean parlour pits. Are longer chop lengths bang on trend or barking up the wrong tree? 

Why chop silage at longer lengths?

Firstly I am no nutritionist, one quick look in the fridge or at the size of my belt will tell you that. But your waist size doesn’t stop people asking you your opinion on things, and I’m repeatedly asked about longer chop lengths.

We all know we should include lots of fibre in our diet, and this is particularly true for the ruminating livestock ration. Long section Non Digestible Fibre (NDF) is critical in promoting rumination, chewing the cud healthy gut condition. Higher NDF also promotes higher butterfats levels in dairy cattle and it’s suggested that it can lead to increased forage intakes.

So does chopping silage longer give higher butterfats?

There are plenty of advocates who will sing the praises of longer length forage, but we need to examine the science (as always). I will refer you to the earlier statement, I’m not a nutritionist but I have been doing some research and the trials don’t seem to back this up. Clever tech has allowed scientists to analyse the materials within the rumen without disturbance to the hosts’ wellbeing – i.e. while she is still alive! The problem seems to be that the livestock are keen to get involved in the process and they tend to grind the forage in the mouth before it gets anywhere near the rumen.

Feeding silage via diet feeder

The results show that the actual average particle size that enters the rumen varies from 9.9mm to 11.1mm – that’s a variation of 1.2mm….

The average particle size of the feed forage was between 12mm and over 43mm.

Now that’s interesting, the actual size of the forage reaching the rumen is not the varying depending on the size it is in the feed trough. The longer stuff just needs more chewing.           

Do longer chop lengths lead to greater forage intakes?

This is another long held belief and there is again lots of anecdotal evidence, but there are several trials that seem to prove the complete opposite. And that makes some sense to me because the more time she spends chewing, the less she can actually consume in any given time period. Now there might be something going on in the background that is not clearly obvious so I am NOT saying the evidence proves the theory wrong. Just that the scientific trials don’t prove the theory correct.

What does not seem to be undisputed is that the level of NDF is vital for production and health. However the actual particle size of the forage does not influence the NDF in the ration.  

Chopping silage longer will save diesel and should speed up the harvest operations but there are some real negatives for the quality of the silage it produces. This is covered in detail in other parts of this series but in essence, longer chop lengths lead to a poorer fermentation and higher in-clamp aerobic losses once the face is exposed to the air.

Kverneland Siloking diet feeder

Some suggest that the balance between chop length and silage quality is a difficult one to achieve. I’m not so sure, to me silage quality is key to farm profitability so I would always choose the chop length to achieve the best nutrient value in the cows mouth.

I still want more long fibre in the ration

So what can you do to get more long fibre into the ration if you decide to avoid long chopped grass? Well in some parts of the world adding some straw into the ration is a really good way of bulking fibre. That’s all very well and good, but in many parts of the UK and Ireland, straw is at a premium and/or is in very short supply.

I can make an argument that if you make the very best silage you can, then you will free up some land compared with a low D-Value bulky high fibre silage crop. It might be possible to grow cereals on the land, either as a grain crop of as a wholecrop silage. And for those who can’t grow cereals, then perhaps is worth making some higher fibre baled silage or haylage. This can be added to the ration to provide some more long fibre if you really need it.

What’s the best source of advice, pub, forum or professional?

As a non-nutritionist, I am NOT qualified to advise on this topic. However wherever you do get your trusted information from, be it the magazines, a Google search, the pub or a neighbour, I would suggest you take as many opinions as you can and then make your own decision. There is clearly some question over the value (or lack of value) from longer chop length in the diet. So I would advise that you do your own research and weigh up the evidence. After all blindly following the fashion of the day can often have some quite unfortunate outcomes, as the old family photo album will undoubtedly testify.

If you want to discuss how to improve your silage or want to discuss any of the other aspects of silage making covered in this series – contact Jeremy Nash at Jeremy@silageconsultant.co.uk

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