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Pima Cotton, Gossypol and Dairy Cattle: Is It a Bad Combination? John H. Kirk1 and G.E. Higginbotham2
July 27, 1999
1Extension Veterinarian, Veterinary Medicine Extension, School of Veterinary Medicine, University of California—Davis, Tulare and 2Dairy Farm Advisory, Fresno/Madera Counties, University of California Cooperative Extension.< /P>
Cotton that is grown in California can be classified into two general groups. Until recent years, most all the cotton was of the upland type. This year for financial reasons as much as one-third of the California cotton is the pima type. Pima cotton i s the name for a group of cotton varieties which produce long staple lint of premium quality. Cotton producers may receive as much as $0.30 per pound more for the pima type compared to the upland varieties. Cotton seeds are a by-products of the cotton industry. Much of the cotton seeds are marketed to the dairy industry as cattle feed. The upland varieties produce a seed which is covered with lint, the so-called "fuzzy seed". The pima varieties produce a seed which is almost bare of lint. The pima seeds look very much like soybeans. The lint acts to slow down the passage of the seed through the cow's digestive tract and helps to ensure complete digestion. As the pima seeds are nearly lint free, they are not as completely digested by the cow as are the upland varieties. To increase the availability of the nutrients in the pima seeds, they are usually cracked or processed in some way. When processed, the pima seeds are essentially comparable to upland se eds in nutrient value and significantly fewer undigested seed are excreted in the feces. All cotton seeds contain gossypol. Gossypol is a yellow pigment found in the glands of the cotton seeds. The gossypol functions to protect the cotton plant from insects. In the seeds, the gossypol is found in the free (toxic) or protein-bound (less-to xic) forms. In the seeds, almost all the gossypol is found in the free form. Heat and moisture processing converts the free form into the less toxic, bound form. Most cotton seeds are feed in the whole or unprocessed form in California due to the lack of processing facilities. Cotton also comes in a (+) and (-) gossypol form. The form is determined by the genetics of the plant. Pima cotton has more of the (-) form than the upland varieties. The (-) form is the more biologically active form of gossypol. Therefore, pima cott on varieties produce cotton seeds which are higher in gossypol content than the upland varieties Toxicity from gossypol depends on several factors which include the form of gossypol (free or bound), the amount fed, the cotton variety, other nutritional considerations, and stress. Signs of acute gossypol poisoning are difficult breathing, violent labored respiration, weakness and death. These signs may appear suddenly after a stressful event and may resemble acute shipping fever. Adult cattle may have decreased milk production, go off feed, have difficulty breathing, weakness and diarrhea. An an alysis of the feed for free and bound gossypol levels may be useful in supporting a diagnosis of gossypol poisoning. The California Veterinary Diagnostic Laboratories can determine the amount of free gossypol present in cottonseeds. The suggested maximum level of feeding for cattle less than one year of age is 0.05% to 0.1% of free gossypol. Adult cattle should have less than 0.1% to 0.2% of free gossypol in the total ration. This amounts to about 6 to 8 pounds of upland cottonse ed per day. For pima cottonseeds, the limit is about 4 to 6 pounds of unprocessed seeds per day. In conclusion, when considering feeding pima cottonseeds in place of upland "fuzzy" cottonseed, keep in mind the following factors:
Pima cotton seeds can be safely fed to dairy cattle if these precautions are followed. Before you begin to feed pima cotton seeds, consult your nutritionist and veterinarian if you are uncertain about feeding pima cotton seeds to your animals.
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