Partial Replacement of Alfalfa Fiber with Fiber from Ground Corn Cobs or Wheat Middlings

Lactating dairy cows require fiber in their diets for proper rumen function, lactational performance, and health. Most dietary fiber is usually supplied from forage, which is in line with NRC ( Decreased fiber content in the diet has been associated with reduced ingestive chewing, rumination, and salivation (4, 17); reduced fiber digestion (13); lower rumen acetate to propionate ratio (11); and milk fat depression Various animal feeds produced as coproducts in feed and food processing contain significant concentrations of NDF. These feeds may be economical sources of fiber, especially when local forage supply is limited. These nonforage fiber sources (NFFS) have smaller particle size than common forage sources and range in dietary energy content below and above that of common forages. Effectiveness of fiber, relative to alfalfa silage, from several different NFFS was ev:aluated by Swain and Armentano (20) using IDllk fat concentration as an indicator of fiber effectiveness. In that study (20), milk fat percentage showed a linear response to increasing amounts of NDF from alfalfa silage and a lesser response to NDF from various NFFS. In a similar experiment (T) in which three concentrations (no, middle, or high) of a single NFFS mixture were fed, milk fat concentration rose linearly with increased fiber from the NFFS mixture, although milk fat concentration from diets based on NFFS were never as high as with the alfalfa diet.