AgEBB-MU CAFNR Extension

Hay Market Listings
A joint venture of the Missouri Department of Agriculture
and University of Missouri Extension

The Value of a Forage Analysis

Forage makes up the major portion of livestock diets. A livestock producer maximizes the value of a forage when the diet is properly balanced considering the nutritional value of the forage. A forage sample needs to be analysed for moisture, protein fiber,(ADF and NDF which allows us to calculate TDN or net Energy) and minerals.
An analysis of a forage is the only positive means of knowing the nutrient content.Book values or guesses can be very misleading in balancing a ration.Underestimating the protein content of alfalfa hay by 2% in a diet fed to dairy cows at 25 lbs./ day could result in the excess feeding of 100 lbs. soybean meal/day to a 100 cow herd.

A hay test should include to following items:

Moisture: Forage sample is fully dried in an oven to determine the % water.Hay will usually have 7-20% moisture.
Crude Protein: A calculated value based on N x 6.25. Made up of true protein and non protein nitrogen. Early cut ,leafy forages are highest in crude protein.
Acid Detergent Fiber: ADF is the % of the highly indigestible portion of the plant.The lower the ADF value , the higher the digestibility and energy value of a hay.
Neutral Detergent Fiber: NDF is the % of the cell wall of a plant. Directly related to fill or intake.The lower the NDF, more the animal can eat.
Relative Feed Value: RFV is an over all indicator of forage quality Calculated from ADF and NDF. Comparing alfalfa, a RFV of 100 equals full bloom mature alfalfa. Grasses at similar stages of maturity will have a lower RFV because of a higher %NDF.

Comparison of forage Quality of a Legume and a Grass

                      High Quality               Low quality 
Analysis         Alfalfa    Orchard Grass    Alfalfa    Orchard Grass
 CP                 20            18            15              8
 ADF                29            31            37             45
 NDF                40            55            50             72
 RFV               160           110           100             80
 NE lac. Mcal/lb. 0.65          0.75          0.56           0.55
 TDN %              63            72            55             54

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