Most commercial laboratories estimate energy content of feedstuffs using regression equations that are based on the negative relationship between ADF content and available energy. A number of equations have been developed by laboratories and research facilities for a variety of grasses and legumes. Functional Fibre Functional fibre describes the physical nature of the feedstuffs. The NDF assay assigns the same fibre to long stemmed hay as is does to finely chopped hay, yet the effect on rumen function and cow health is much different. The long particles in forage stimulate rumination which stimulates saliva production.
Saliva contains buffers which neutralize acids produced in the rumen during digestion of feeds.
For forages in the long form, time spent eating and ruminating increases as the amount of the forage consumed or concentration of fibre in the diet increases. A dairy cows consuming 4 to 6 kg of NDF per day will spend 3 to 5 hours eating and 4 to 7 hours ruminating. The fineness of chop will dictate how much of reduction occurs. The actual chop length will vary depending on the efficiency of the forage harvester.