Forages are, in general, the least expensive source of energy for dairy cows. However, the efficiency of converting forages to milk is limited by the digestibility of forage cell walls. Under ideal feeding conditions cell wall digestibility in the total digestive tract is still generally less than 65%. Average fibre (NDF) digestibility of forages reported by a commercial laboratory from Minneapolis, MN at 30, 120, and 240 hours were 54 (range: 43-64%), 71 (63-80%), and 74% (66-84%) of NDF for corn silage, and 38 (27-49%), 41 (30-52%), 42% (30-53%) of NDF for alfalfa hay.
Digestibility of corn and alfalfa silages
Using these fibre digestibility times on the Rafrenatto rate calculator for NDF from the NDS software platform, the average degradation rate for corn silage and alfalfa hay were 4.4 and 8.3%/hour, respectively. It can be observed while corn silage contains the greatest amount of digestible fibre, alfalfa hay is digested at much faster rate.
Two recent experiments carried out at the South Dakota State University Dairy Research and Training Facility tested different forage concentrations on highproducing dairy cows.
Continue reading this article published in Dairy Herd Management.