Submitted to: Journal of Cotton Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/16/2000
Publication Date: 10/16/2000
Citation: Buser, M.D. 2000. Dry extruding cotton gin by-products to reduce chemical residues. Journal of Cotton Science. Vol. 5: 92-102
Interpretive Summary: An estimated 2.5 million metric tons of cotton gin by-products (CGBP) other than cottonseed are produced annually by U. S. cotton gins, creating a significant disposal problem in the ginning industry. Currently, the most common methods of disposal include composting, direct land application, and livestock feed. Surveys estimate that 37% of U. S. cotton gins utilize CGBP at a profit or at no cost, while the other 63% pay for disposal. The nutritional value of CGBP is similar to roughage- type feeds, which has created an interest in adding this material to livestock feed rations. The primary concern associated with feeding CGBP to livestock is the potential for chemical residues in the material. To address this concern, mixtures of CGBP and cottonseed were extruded under high pressure and high temperatures to determine the chemical residue reductions associated with the process. Results from the extrusion tests indicated that residue levels of the chemicals tested were generally decreased by the extrusion process and further diluted by addition of cottonseed to the CGBP. The extrusion process did not appear to substantially change the nutritional value of the mixtures and increasing the amount of cottonseed in the mixture enhanced the nutritional value of the product. Although these tests indicated that the extrusion process reduced chemical residue levels, feeding CGBP is not recommended until tolerance levels have been established by the Environmental Protection Agency under the Food Quality Protection Act. The ability to utilize CGBP in livestock rations will increase gin profits, reduce landfill disposal, and generate an alternative roughage type feed for the livestock industry.
Technical Abstract: Whole cottonseed and cotton gin by-products (CGBP) were mixed together and processed in a dry extruder to determine the feasibility of using the mixture as a livestock feed. Samples were collected during the study to determine if product temperature, pressure, and shear associated with extrusion would reduce chemical residue levels in CGBP and affect the nutritional value of the mixture. The first test focused on various mixing ratios of CGBP and cottonseed with a constant temperature and pressure during processing. Results show a significant reduction in Methyl Parathion and DEF, while there were no significant reductions in Karate levels. Initial Karate levels were below 1 ppm prior to the extrusion process. The second study focused on extruding a mixture of 75% CGBP and 25% cottonseed processed multiple times by dry extrusion. The results of this study show significant reductions in Methyl Parathion and Dropp. Nutritional analyses of the extruded material from the first study showed significant differences in nutritional values of the various mixtures, primarily due to the differences in mixture composition. Nutritional results from the second study showed significant differences in nutrient values due to the number of times the material was processed. The 75% CGBP and 25% cottonseed extruded mixture maintained a relatively high nutritional value with respect to roughage-type materials.