Effect of whole and expanded-expelled cottonseed on milk yield and blood gossypol

Thirty-two primiparous and 12 multiparous Holstein cows were randomly assig ned at calving to treatments to determine the effects of type and amount of cottonseed product on plasma gossypol, milk production, and composition, a nd conjugated linoleic acid concentration in milk fat. Rations consisted of corn silage, corn grain, soybean meal, and cottonseed hulls, and contained on average 16.8% crude protein and 25.3% acid detergent fiber on a dry mat ter basis. On a dry matter basis, diets contained one of the following: 1) 14% whole cottonseed; 2) 14% expanded-expelled cottonseed; 3) 21% expanded- expelled cottonseed; or 4) 28% expanded-expelled cottonseed. Cows remained on treatment from 30 through 120 d in milk. Dry matter intakes were not significantly different, but intakes of crude p rotein, acid detergent fiber, and fat were higher for multiparous cows fed whole cottonseed. Multiparous cows fed whole cottonseed had higher yields o f milk, fat-corrected milk, crude protein, fat and solids-not-fat than thos e fed any level of expanded-expelled cottonseed. Concentrations of milk fat , protein, and SNF were not affected by treatment. Although there were trea tment differences in fat intake, there were no production differences in pr imiparous cows. Milk production efficiency (fat-corrected milk/dry matter i ntake) was not affected by treatment for either multiparous or primiparous cows. Cows fed 14% whole or 14% expanded-expelled cottonseed had similar le vels of total plasma gossypol and plasma levels of the negative isomer of g ossypol. Increasing the level of expanded-expelled cottonseed in the diet i ncreased both total plasma gossypol and the negative isomer. In this experi ment, multiparous but not primiparous cows fed whole cottonseed produced mo re milk than those fed expanded-expelled cottonseed at 14 to 28% of the die t dry matter, however, feed efficiencies were similar for all treatments.