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While cotton is grown mainly for its fibers, the seeds removed by ginning produce roughly 300 pounds of oil per ton. It's used for shortenings and soaps. The meal left behind after the oil is pressed is a high-protein livestock food sometimes used to supplement a laying hen's diet. Overfeeding cottonseed meal results in adverse effects on both egg production and egg quality.
While all cottonseed provides protein, the different oil-extraction processes produce products with wide variances in nutrition and toxicity. Screw-pressed or expeller-pressed meal uses a mortar to press out cottonseed oil, leaving as much as 20 percent of the oil in the meal. Solvent extraction uses hexane to extract up to 90 percent of the oil and heat to vaporize the solvent before grinding it into meal. A third method removes 97 percent of oils by combining the press and extraction methods.
A natural pigment with anti-cancer properties known as gossypol passes to eggs. When consumed directly by nonruminants such as humans and chickens, gossypol is toxic in large amounts when consumed regularly. Contained within a hen egg, gossypol is is digestible by humans, being released in the digestive tract without toxic effect. When it's fed to hens in quantities exceeding an ounce of meal per day, hens will decrease egg production and food utilization as well as developing abnormal crops.
Cottonseed meal increases a hen's intake of saturated fat, which is passed through to her eggs. Too much cottonseed meal in a hen's diet will also cause the egg whites to become pink and yolks to be rubbery. Gossypol contains both yellow and brown pigments, and various studies of hens eggs have noted discoloration ranging from a mottled yolk to brown or even greenish yolks. Eggs stored for long periods of time showed most discoloration.
Cotton meal made from new strains of glandless cotton that does not cause gossypol toxicity can be a means of supplementing your hen's diet with more protein. The presence of gossypol in the cotton plant naturally repels pests, and glandless varieties can be high in toxic residue from pesticides used to do gossypol's job. Supplemental iron can combat the effects of gossypol when hens are fed less than 10 percent of the diet in cottonseed meal, resulting in yellow-orange yolks that do not discolor when stored.
- U.S. National Library of Medicine National Institute of Health: Effects of Dietary Cottonseed Meal and Iron-Treated Cottonseed Meal in Different Laying Hen Genotypes
- U.S. National Library of Medicine National Institute of Health: Effects of Dietary Cottonseed Meal, With and Without Iron Treatment, on Laying Hens
- University of Florida: Egg Quality [PDF]
- Purdue University: Cottonseed Oil
- The Ohio State University College of Veterinary Medicine: Enhanced Chickens, Eggs May Prevent Breast Cancer
- Poultry Science: Cotton Seed Meal as a Poultry Feed
- The Journal of Applied Poultry Research: An Evaluation of Low-Gossypol Cottonseed Meal in Diets for Broiler Chickens
- Feedipedia: Cottonseed Meal
- Cotton Today: The Saga of Ultra Low Gossypol Cottonseed
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