Reasons why you shouldn't be feeding calves straw

Nothing stimulates a discussion better than bringing someone in with totally different views. And that’s just what happened when we met up with Jud Henrichs this week. The greatest benefit of this is the willingness to question the status quo and come up with new ideas and alternative strategies. Jud is as we know a passionate advocate of early weaning but it was not that issue that will form the basis of this blog.

Personally, I have never understood why anyone would want to feed straw to weaned calves, apart from the caustic-treated straw of course. In my mind, straw is for bedding and not for feeding, and I feel I can make a good case to support my philosophy.

Before I begin to make my case, it is worth noting that Jud was quick to point out that the UK is one of the few first-world dairy countries around the globe that feeds straw to youngstock. Although I am not suggesting that there is a direct scientific or statistically significant association, it is worth pointing out that we have one of the highest ages at first calving and the lowest milk production per cow.

So to my philosophy; straw consists of heavily lignified fibre and therefore high levels of undegradable NDF (uNDF) which has been shown by workers at Cornell University to be a major determinant in the regulation of DMI. This is one of the benefits of using NIS as opposed to straw. Analysis of NIS has shown that the caustic treatment reduces the proportion of uNDF in straw making it more digestible. Conventional straw is low in energy and protein and therefore will yield less VFA (Volatile Fatty Acids) and microbial protein than better-quality forages or concentrates. In order for the straw to be transported out of the rumen it needs to be physically broken down by rumination as most plant material is resistant to microbial digestion. This requires large amounts of energy which will be diverted from growth.

The net effect of feeding straw is as follows;

1. It will reduce DMI
2. It will reduce the production of VFA and microbial protein which will retard rumen development and protein supply to the animal.
3. The digestion of straw is inefficient
4. All these factors interact to reduce development and growth.

The alternative is to offer a quality forage such as haylage. Feeding hay has all but nearly gone out of fashion because it produced pot-bellied calves. I believe the reason for this is not directly related to the hay but to the fact that insufficient concentrate was fed in conjunction with the hay. This resulted in the calves gorging on the hay to satisfy their appetite and becoming pot-bellied. When the insufficient concentrate is fed the nutrients required to stimulate microbial digestion are reduced leading to a reduction in rumen function. I am of the opinion that this does not happen with straw due to the fact that the high percentage of uNDF in straw actually restricts its intake.

The other benefit of feeding a partially fermented forage to calves is that the lactic acid can be used as an energy source for rumen microbes and will also stimulate the bacteria that convert lactic acid from starch fermentation into propionic acid which is subsequently absorbed and converted to glucose in the liver.

For those of you who I have convinced that this is the way forward here are some guidelines.

1. Make high-quality haylage greater than 40%DM and well chopped.
2. Avoid grass with high-free nitrates.
3. For ease of management conserve as big square bales and ensure to double wrap and use a preservative suited to high dry matter forage. This will ensure good fermentation and the absence of mould.
4. Do not reduce concentrate feeding levels. Concentrates should provide at least 80% of the DMI of the calf in the early 5-week to post-weaning period. Remember fibre will govern dry matter intake.
5. Use a high-quality calf starter concentrate such as Wynnstay’s Start ‘n’ Wean.

I strongly recommend that this summer we look at the potential to make high-quality haylage for our calves based on my thinking that straw is for bedding and not for feeding.