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.