Neutral Detergent Fibre

Neutral Detergent Fibre (NDF): is a measure of total insoluble fibre contained in a ration. The individual components that contribute to NDF are hemicellulose, cellulose, lignin and some protein fractions. In forages, NDF has a strong correlation with total organic matter digestibility and estimations of energy (MJ). As forages become more mature, NDF increases and digestibility decreases. This is the underlying reason for ensuring that only
the highest quality forages are fed to lactating dairy cows. 

In forages, increasing NDF values are often attributed to declining dry matter intake (DMI), based on the theory that higher
NDF values contribute to greater gut fill. On the other side of this equation, very low levels of forage NDF in a total ration can predispose cows to a greater risk of sub-acute ruminal acidosis (SARA) and a subsequent reduction in DMI. For lactating cows, the ideal NDF of the total ration is in the range of 28-32% NDF. 

Forage NDF should be considered separately from the total ration NDF, as forage NDF has different physical properties that assist rumen motility, endogenous buffering and volatile fatty acid (VFA) absorption when compared to sources of non-forage NDF. Forage NDF should not be less than 220g/kg of the total ration and should be held in balance with total ration fermentable carbohydrates.

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