Feeding potatoes to pigs

I sometimes wish people would get off their bums and do a little research before touting their pet theories on the issue of the day.

Take the relatively simple matter of whether it’s okay to feed potatoes to pigs and, if so, whether they should be cooked or raw.

It’s a question that pops up on self-sufficiency and smallholder forums fairly frequently, and it’s also one that floats into my email in-box from time to time.

The answer is that potatoes can be fed raw to pigs, sheep and cattle, but pigs have difficulty digesting potato starch in moderate to large quantities. Too much starch equals stomach upsets.

Cooking overcomes this and the potatoes then become a good energy source for pigs.

It means that pigs rooting up a few left-over potatoes in a field will be fine, but they should not be fed quantities of raw potatoes as part of their morning and evening rations.

Cattle and sheep being ruminants, on the other hand, can more effectively digest raw potato starch.

But even for sheep and cattle, too large an amount of potatoes can result in starch bypassing the rumen and reaching the lower intestinal tract where it results in stomach upsets and scours.

It must also be remembered that potatoes are a high-energy, high-water, low-fibre, low protein feed.

Feed that’s too high in water content lowers animal feed intake and reduces daily weight gain, while additional roughage may be needed to counter the low fibre content.

The high water content means 4.5kg of potatoes is the broad equivalent of one kilogram of barley.

We supplement our pig rations with cooked potatoes, but never more than 20% of the daily ration. (The UN Food and Agriculture Organisation gives 6kg of cooked potatoes per day as the upper limit for adult pigs.)

As far as poisoning is concerned, it’s only green potatoes plus any sprouts, stems and haulms that are the problem.

If none of these are in the ration, then there is no danger of alkaloid poisoning. (Having said that, if pigs do root up and eat one or two green potatoes in a field they will be okay – it’s when they have them in large numbers in one go or eat a small amount regularly over a long period that poisoning will result.)

The Internet allows access to scientific papers and government guidelines for feeding potatoes to livestock, so use Google or get a few books and read up on the subject first.

16 Responses to “Feeding potatoes to pigs”

  1. I’ve had a couple of aggressive emails in the past 24 hours from people who doubt the veracity of what I’ve written here, particularly in relation to the water and protein content of potatoes, the need to cook potatoes before feeding pigs, and the reduction in daily weight gain caused by over-feeding very wet feedstuffs to pigs.

    For the doubters, I’ll list some of the material I used as sources for my original post:

    Water content ranges from 60% to more than 85%. On a dry-matter basis, potatoes contain 4% to 6% ash, 10% to 11% protein, 4% fiber, 0.2% fat, and 82% to 83% soluble carbohydrates (nitrogen-free extract). Raw potatoes contain alkaloids, protease inhibitors that depress growth and feed consumption. Cooking is required to destroy these heat-labile inhibitors and to alter the starch fraction so as to improve starch digestion.

    Pig Production: Biological Principles and Applications, John McGlone, Wilson G. Pond, Thomson Delmar Learning, 2002

    Pigs fed a diet containing cooked potato grew faster and converted feed to live weight more efficiently than pigs fed the same amount of a diet containing between 14 and 26% of the DM as raw potato. The presence of raw potato in diets was also found to reduce appetite.

    Influence of cooking upon the nutritive value of potato and maize in diets for growing pigs, Colin T. Whittemore, Ian W. Moffat, Alexander G. Taylor
    Department of Animal Production, School of Agriculture, University of Edinburgh, published in the Journal of the Science of Food and Agriculture, Volume 26 Issue 10, 9 May 2006

    Potatoes are high in moisture (65 to 72%), but on a dry weight basis, potatoes contain 6 to 12% crude protein and are high in starch with little fibre and ash. For optimum utilisation, potatoes should be cooked (100C) before feeding. Cooking improves starch availability and denatures an alkaloid glycoside (solanine) and a protease inhibitor found in raw potatoes (Edwards and Livingstone 1990). Cooked potatoes are readily accepted by pigs with their only drawback being their high moisture content, which reduces daily nutrient intake, especially in young growing pigs.

    Swine Nutrition: Second Edition, Austin J. Lewis, Lincoln Lee Souther, CRC Press, 2000

    Potatoes are an excellent energy source for ruminant livestock (cattle and sheep) but the presence of anti-nutritional factors, as well as the difficulty in digesting potato starch make raw potatoes low in feed value for pigs. Cooked potatoes make a good energy source for pigs but feeding raw cull potatoes directly to cattle usually makes more economic sense.
    Moisture Level
    Because potatoes are 75-80% water, care must be taken to avoid combining them with other wet feeds to give a diet with greater than 70% moisture content; wet rations often lower feed intake and daily gains particularly in cold weather.
    The wet manure that high moisture diets often cause makes it difficult and costly to keep animals dry and comfortable and is another reason for reduced performance on wet rations.
    Fibre Levels
    The digestive problems sometimes blamed on the high moisture content of potatoes are in fact related to their very low fibre content. When high levels of potato are fed, a source of fibre (roughage) is necessary in order to maintain a normally functioning and healthy rumen.

    Feeding Potatoes to Cattle, New Brunswick Department of Agriculture and Aquaculture,

    Potatoes, carrots, sugar beet, silage and fodder beet can all be used but nutritional balance and other factors must be taken into account. To get the nutritional value of 1kg of concentrates, 6kg of potatoes would have to be fed.

    Save Money on Cull Sow Feed, BPEX, 23 October 2007,

    I’m out of time now, so suffice to say that I used more sources than these and was very careful to base what I wrote on the science, even if in simplified form.

    Also, I’m fairly certain which forum the doubters were coming from so I suggest they tone down their language before it gives their particular on-line community a bad name.

  2. Thank you so much for your very informative information regarding feeding potatoes to pigs.

    Kind regards

    Eddie Marshman

  3. I have a pet pig and a paddock full of potatoes. Do you think that letting her in for an hour or so with the neighbors cattle who will be eating the potatoes left after harvesting would be a terrible idea?

    • What is a good thing to mix with potatoes then? other than concentrates, would Bran be a good subsitute for the lack of fibre in the potatoes?

      • We mix rolled barley with potatoes. The main thing is to remember that while pigs can utilise around 90% of soluble fibre, they can’t utilise insoluble fibre. More insoluble fibre in a pig’s diet means more of the feed will pass straight through them and become manure.

  4. What are your thoughts on goats eating raw potatoes? Same as cattle and sheep? We have an incredible surplus of potatoes and are looking for ways to use them before they spoil. But our goats are our most prized animals, and we don’t want to make a foolish mistake when it comes to their welfare. Our one pig has been enjoying them, but it has probably been eating too much of them as it is, so we’ll need to ‘spread the wealth’!

    • Sorry, but I haven’t a clue about goats. I know they’re ruminants, and browsers not grazers. But that’s about it.

      Can goats eat other members of the nightshade family? (Potatoes being of the Solanaceae family.) If so, they might be okay but I suggest you find a goat expert and ask them first.

  5. It’s odd that people would angrily email you about your feeding prcatices. Even a brief ten minute trawl on repuatble websites throws up a ton of info that agrees with you. Cook the potatoes. Limit them to a percentage (I’ve seen up to 25%), and cook them, due to digestibility issues.

    I like the ideas of mixing it all together in a warm mash. Thinking of growing oats at my place for the pigs I plan to have next year ( agaiun, sugestions are that oat intake is limited to a percentage of feed too, due to possible limitations with nutritional uptake at the 50 per cent mark – need to do some more research here).

    Thanls for the informative posts. Keep up the good work.

    • Many people get angry when anything is said that doesn’t agree with their preconceived notions. They don’t wish to change their mind, therefore anyone who says different is wrong, making them a threat. Anger is the result.

      As far as as feeding oats—or barley for that matter—is concerned, pigs need a balanced diet that meets all their nutritional needs. A diet based wholly or largely on one foodstuff is not going to meet that need. Pigs fed largely or entirely on barley and/oats for example, tend to run to fat because cereals are short in the amino acids necessary to convert protein to muscle. Without those amino acids, more of the protein intake is converted to fat.

      We feed sow rolls as the major part of our pigs’ diet because they are designed to provide a specific balance of nutrients and other elements. We use other feedstuffs—vegetables, fruit, barley—as supplements to their main diet, particularly in winter when grass is in short supply and the pigs need more energy to cope with cold weather. We don’t rely on those alone, however, because getting the nutritional balance right is quite complex.

      We could do it—for example by growing peas and barley together, processing them together and adding supplements—but for our purposes it makes more sense to use the commercial sow rolls, with fruit and vegetables on top plus barley as appropriate.

  6. So pigs aren’t meant to eat raw potatoes

    Wish someone had told pig 455 when it escaped from the field next door and discovered our raised bed with some potatoes in it.

  7. My pigs get a good handful of boiled potatoes for their breakfast along with a few beets and carrots and for supper they get a few handfuls of SPROUTED grains (I sprout the grains, or at the very least soak them overnight, as pigs would never encounter dried grain in the wild and it is likely to be as damaging to their digestive systems as it is ours), sprouted lentils, seeds, pulses etc. As well as the standard pig bucket offerings – peelings, left over wholemeal bread etc. Once a week they get the odd free range egg and a sprinkling of either rock dust or liquid seaweed. I am expecting some very tasty bacon. It does cost more but then so do most things when you do it properly. Bagged pig nuts that equate to around an 80% grain diet is cheap, convenient and not good for pigs…or any creature really.

  8. thanks for the info, we’ve been getting leftover fruits and veggies from a big supermarket, tons of potatoes come with it, along with oranges- which the pigs don’t care for at all, cutup or otherwise. there are 5 sows, a boar and 12 feeders here so the extra helps with grain bill. i have those automatic metal feeders and have been giving the equilivant of 6 lbs per pig at night after they’ve been chowing all day.

  9. Sir sweet potatoes do not belong to the nightshade family.


  1. How to make your pigs happy « Musings from a Stonehead - 25 October, 2007

    [...] potatoes are boiled up for 20 minutes until they start falling apart and are then tipped, water and all, into large [...]

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