Rick Titel, Ration Analyst
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Cows have the ability to digest part of the Neutral Detergent Fiber (NDF) of a feed and turn that into energy. NDFd is a test that is available for forages to determine the digestible part of the forage. The price for the NDFd test ranges from $8 to $24 additional investment per individual forage sample. NDFd will be used to predict energy from the forage more precisely than we could before.
Most of the cow's energy comes from Carbohydrates (CHOs). CHO's is made up of Non-Fiber Carbohydrates (NFC) and NDF. If NDFd is high, then cows need less energy from the NFC. If NDFd is low, then cows could require more grain than we can feed.
NDFd is helpful for preventing and troubleshooting problems related to fiber digestibility. The higher the milk production the more likely you will want to use NDFd on a regular basis. At the very least you may want to use it one time per crop per year. We also suggest you use NDFd for troubleshooting a low production problem while feeding a "high quality, low fiber forage." These forages may have high RFV (relative feed value) but still have a low NDFd. This causes the ration to be insufficient in both fiber and energy at the same time. It appears that about 20% to 30% of the haylage samples could be like this.
What if the NDFd is low? There are three options:
• Replace forage with another forage that is higher in NDFd
• Add highly digestible fiber commodities (i.e. soy hulls or beet pulp)
• Change the ratio of forages in favor of the higher NDFd forages
Be sure to monitor these factors:
• Changes in production numbers: milk, fat% and protein%
• Changes in manure consistency
Determine options:
• Ration change options: Can we partially substitute another forage higher NDFd or use a different forage?
• Are soy hulls or beet pulp available? Price/ton?
• Can we change the supplement to include soy hulls or beet pulp or add them into the diet separately?
Production Effects:
Cows fed a "low NDFd" forage drop in milk production more quickly than they will come back up (if they come back up at all).
To prevent loss in production from occurring you can do these things:
• Test NDFd while the cows are doing well to get a basis for when it changes.
• Whenever possible test forages prior to feeding or immediately when starting to feed the forage.
• Contact your consultant routinely when forages change.
• Use NDFd as a tool to help you manage forages better.
• Communicate as much information as you need to your consultant.
