Effect of Whole Cottonseed, Gossypol, and Ruminally Protected Lysine Supplementation on Milk Yield and Composition

¹ Department of Animal Sciences, Washington State University, Dairy Forage Facility, Puyallup 98371-4998
² Texas A&M University, Agricultural Research and Extension Center, 7887 N. Highway 87, San Angelo 76901

To determine whether the gossypol content of the diet affected availability of dietary Lys, 4 cows with ruminal and duodenal cannulas and 16 intact cows in early lactation were assigned to diets containing either glanded cottonseed, glanded cottonseed plus 15 g/d of ruminally protected Lys, glandless cottonseed, or glandless cottonseed plus 15 g/d of ruminally protected Lys. The experimental design was a 4 x 4 Latin square design with 3-wk experimental periods.

Gossypol concentrations in plasma were lower when cows were fed glandless cottonseed. Lysine supplementation increased the flow and percentage of Lys in duodenal digesta and increased the concentration of Lys in plasma. Neither type of cottonseed nor Lys supplementation affected dry matter intake. Yields of milk and fat-corrected milk from cannulated cows were not affected by diet, but yields from intact cows were increased by Lys supplementation. For both cannulated and intact cows, Lys supplementation increased the percentage of milk protein, and milk protein yield was increased by Lys in intact cows. Dietary gossypol did not affect the response to Lys, indicating that dietary gossypol had little or no effect on the availability of Lys for dairy cows.

Key Words: gossypol • lysine • whole cottonseed • milk protein

Submitted on April 22, 1996
Accepted on December 13, 1996

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