Response of lactating dairy cows to mechanically processed whole cottonseed

Twenty-four lactating Holstein cows averaging 142 +/- 34 d in milk were used in a replicated 4 x 4 Latin square trial to determine the effect of processed whole cottonseed on milk yield and nutrient digestibility. Fifteen percent of the dry matter content of the experimental diets consisted of whole cottonseed, roasted whole cottonseed, a roasted and pelleted blend of whole cottonseed and soybean meal, or an extruded blend of whole cottonseed and soybeans. Apparent digestibilities of dry matter and neutral detergent fiber were higher, and total fatty acids were lower, for cows fed extruded cottonseed than for cows fed roasted cottonseed. No differences were observed among treatments for dry matter intake, milk yield, protein, lactose, SNF, energy-corrected milk, percentages of milk lactose, or percentages of SNF. Milk fat percentage was greatest for cows fed whole cottonseed and roasted whole cottonseed, intermediate for cows fed roasted and pelleted cottonseed, and lowest for cows fed extruded cottonseed. Yield of milk fat was lowest for cows fed extruded cottonseed. Milk protein percentage was lower for cows fed roasted and pelleted cottonseed than for cows fed roasted whole cottonseed. Cows fed extruded or roasted and pelleted cottonseed gained body weight, but cows fed whole or roasted cottonseed lost body weight. Total gossypol concentrations differed among treatments; the concentrations were greatest for cows fed the roasted cottonseed and lowest for cows fed the extruded cottonseed. Processing of cottonseed appears to alter nutrient digestibility and milk composition.