Ask the Vet

By Dr. Ken McMillan
DTN/The Progressive Farmer Contributing Editor

Question: I like to feed whole cottonseed to cattle at a rate of 2 pounds per cow, two to three times a week. I have horses pastured with the cows. I heard whole cottonseed is bad for horses, so I keep them away when feeding the cows. Recently, I was told whole cottonseed can make bulls sterile. What is fact and what is fiction when it comes to whole cottonseed?

Answer: I love whole cottonseed (WCS), but there are definitely some issues with it that need consideration.

To answer your question, I started by checking with several equine experts. What do they think about feeding WCS to horses? Some felt the small amounts you are talking about would probably be safe for mature horses, but no one actually advised feeding it to them.

Having owned horses my entire life, I can attest that they are a continual challenge. Horses have no brain when it comes to eating. I am convinced they will eat until they colic or die. My horses have always run cows off of feed, so I would be concerned that your 2 pounds per head could be much more for a horse, assuming he eats his share plus some. I would advise you to continue to separate the horses from the cows when feeding WCS.

The main problem with WCS is that it contains gossypol, which is toxic to animals. The level of gossypol varies by cotton variety, as well as by growing season. Non-ruminants, such as swine, chickens and horses, are more susceptible to gossypol poisoning because they don't have a rumen to detoxify it. Calves, lambs and kids are essentially "non-ruminants" until they are 2 to 3 months of age.

The issue of gossypol and bulls continues to be controversial. Gossypol has been shown in some studies to cause a temporary reduction in sperm cell formation in bulls, but other studies have not been able to replicate this finding.

Any infertility due to gossypol would take several months to develop so feeding appropriate amounts to the cow herd during breeding season should not be a problem.

I personally do not feel the data supports not feeding WCS in small amounts to bulls at any time. However, having said that, bull fertility is so important to the bottom line that the small savings is not worth the risk.

(VM/CZ)

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