REPLACEMENT OF ALFALFA NEUTRAL DETERGENT FIBER WITH A COMBINATION OF NONFORAGE FIBER SOURCES

Sixteen Holstein cows in midlactation were used in a 4 x 4 Latin squar e design to determine the effect of replacing alfalfa neutral detergen t fiber (NDF), with NDF from a combination of whole linted cottonseed, dried distillers grains, and wheat middlings. The four diets were a b asal control diet that was low in forage and fiber [(5.9 g of corn sil age NDF and 6.1 g of alfalfa NDF/100 g of dry matter (DM)], a normal f orage diet (low forage plus 10 g of additional alfalfa NDF/100 g of DM ), and two low forage diets with either 5 or 10 g of NDF from the nonf orage fiber sources added per 100 g of DM. Milk yield, milk protein yi eld, and milk protein percentage were higher, and milk fat percentage and fat yield were lower, for cows fed the low forage diets than for t hose fed the alfalfa control diet that was higher in fiber. Among the low forage diets, dry matter intake, milk fat percentage, and fat yiel d all increased linearly as NDF content increased. The ratio of acetat e to propionate in the rumen and rumination times were greater for the normal forage control diet than for the high nonforage fiber diet. Ad ded NDF from these nonforage fiber sources increased milk fat percenta ge and yield, but this increase was less than the NDF from alfalfa and less than predicted. In agreement with results of similar previous tr ials, milk protein yield and percentage were increased when alfalfa ND F was replaced with fiber from nonforage fiber sources.