The effects of feeding varying amounts of gossypol from whole cottonseed and cottonseed meal in lactating dairy cows

Effects of feeding varying amounts of total gossypol from whole cottonseed and cottonseed meal were evaluated in 30 lactating Holstein cows. After a 1 4-d pretreatment period, cows were assigned for 42 d to one of five treatme nts: control (diet A); 1040 mg/kg of total gossypol, and 989 mg/kg of free gossypol from whole cottonseed (diet B); 900 mg/kg of total gossypol and 64 mg/kg of free gossypol from cottonseed meal (diet C); 960 mg/kg of total g ossypol and 531 mg/kg of free gossypol with equal amounts of total gossypol from whole cottonseed and cottonseed meal (diet D); or 1922 mg/kg of total gossypol and 1050 mg/kg of free gossypol with equal amounts of total gossy pol from whole cottonseed and cottonseed meal (diet E). Concentrations of p lasma gossypol and its isomers were directly proportional to free gossypol intake. Plasma gossypol concentrations plateaued after 35 d on treatment, a nd they were highest in cows receiving diet E. At 42 d on treatment, erythr ocyte fragility was higher in the cows receiving the diet E, but it did not differ among other treatments. Dry matter intakes were similar for all gro ups. Cows receiving diet E produced more milk and 3.5% fat-corrected milk, but milk protein content decreased. Feeding diets containing 1900 mg/kg of total gossypol and 1050 mg/kg of free gossypol for 42 d resulted in increas ed plasma gossypol concentrations and erythrocyte fragility, but no detrime ntal impact on lactation performance were observed.