EFFECTIVENESS OF NEUTRAL DETERGENT FIBER IN WHOLE COTTONSEED AND DRIED DISTILLERS GRAINS COMPARED WITH ALFALFA HAYLAGE

Sixteen Holstein cows in midlactation were used in a 4 x 4 Latin squar e design to determine the effect of replacing alfalfa NDF with NDF fro m whole, linted cottonseed or dried distillers grains. Low and high fi ber control diets (13 and 19% of dietary DM from alfalfa haylage NDF, respectively) were compared with diets designed to contain 13% of DM f rom alfalfa haylage NDF plus 6% of DM from either cottonseed NDF or di stillers grains NDF. Dry matter intake, milk yield, and milk protein y ield were lower for the high fiber control diet. Milk fat percentage w as lower for the low fiber control diet. The cottonseed diet was equal to the high fiber control diet in stimulating rumination. Rumen aceta te to propionate ratio was higher for the high fiber control and cotto nseed diets. Replacing alfalfa with either of these high fiber by-prod uct feeds increased feed intake and yields of milk fat and protein. Th e effectiveness of the NDF in distillers grains and cottonseed was not significantly different from that of alfalfa NDF for maintaining milk fat yield. Whole cottonseed and dried distillers grains appear to be good sources of effective, fiber for maintaining milk fat test when th ey are substituted for alfalfa haylage fiber in lactating cow rations.