As the winter is winding down, many producers are getting ready to turn out bulls. Often, the supplement used for the cow herd contains whole cottonseed, and this prompts questions such as, “Can I feed whole cottonseed to my bulls?” and, “Will it make them infertile?” Our answer to this question is always, “Absolutely not, if you stay within the recommended feeding levels." Currently, the recommended inclusion rate is 0.5% of bodyweight or 20% of the total ration. This recommendation is made, however, due to the amount of fat in whole cottonseed (approximately 20%), rather than the amount of gossypol, which is a common driver for concern when feeding whole cottonseed. Gossypol is a yellow pigment found in the stem, leaf, lint and seed of the cotton plant, but it is highly concentrated in the seed. Gossypol acts as a natural defense agent for the cotton plant by promoting infertility in insects that consume it.
Gossypol has been studied extensively for years and has been shown to be toxic to monogastrics (humans, pigs, mice, etc.) and pre-ruminants (calves, sheep, goats, etc., whose rumen has not developed yet). Most research indicating issues when feeding whole cottonseed to bulls was conducted from the 1960s through the 1990s and included whole cottonseed at up to 40% of the diet, which is much higher than the recommended level. Additionally, many researchers that reported issues were feeding pima cotton, which is much higher in gossypol than upland cotton and uncommon in the southeastern U.S. Due to the lack of current research applicable to the area, a study was conducted at the University of Georgia to determine whether whole cottonseed has an effect on performance or semen morphology of 16- to 18-month-old beef bulls.
Over two years, 46 Angus and Red Angus bulls were transported in the fall to a research barn in Tifton, Georgia. The bulls were randomly assigned to one of three treatments:
- 7 pounds of dried distillers grain;
- 3.5 pounds of dried distillers grain and 3.5 pounds of whole cottonseed (0.33% of bodyweight); or
- 7 pounds whole cottonseed (0.7% of bodyweight).
Bulls were weighed and given a breeding soundness exam on days zero, 30 and 60. The project was scheduled for 60 days to mimic a controlled breeding season as well as to allow spermatogenesis to occur.
Bulls that were fed whole cottonseed had a lower average daily gain (ADG) than bulls fed dried distillers grain (2.12 versus 3.06 pounds per day), but there were no differences in normal semen morphology. To pass a breeding soundness exam, bulls must maintain normal morphology equal to or greater than 70%. As shown in Table 1, all bulls in this study had normal morphology greater than 70%.
From a nutritional standpoint, whole cottonseed is an excellent feedstuff when utilized correctly, and due to high levels of cotton production in Georgia, whole cottonseed is often readily available. Nutritionally, it is high in energy (95% total digestible nutrients), protein (24% crude protein) and fat (approximately 20%), and is a great supplemental feedstuff in times of limited or low-quality forage availability.
When the price of whole cottonseed allows it to be used, it can be an excellent feedstuff. If you are having issues with fertility in your bulls, make sure all other aspects of bull management are in place (e.g., breeding soundness exam, injury management, etc.). Very rarely, if ever, will whole cottonseed cause infertility in bulls when fed properly. If you have any questions on whole cottonseed or would like help incorporating it into your nutritional program, contact your local cooperative extension office.