Alfalfa Quality

• Alfalfa is very digestible. With improved digestibility there is an increase in forage consumption compared to grasses, leading to increased animal performance.

• High quality alfalfa hay or haylage has good leafiness, bright green color, pleasant smell, fine bendable stems and is free of foreign material and mold.

• Objective measurements of forage quality include the laboratory analysis of crude protein (CP), neutral detergent fibre (NDF), acid detergent fibre (ADF) and total digestible nutrients (TDN).

• The NDF fraction is insoluble in neutral detergent and is made up of the plant cell wall which is partially digestible. Low NDF values are desirable and are associated with increased dry matter intake (DMI).

• The ADF fraction is insoluble in acid detergent and is the indigestible part of the cell wall and includes lignin and silica. A low concentration of ADF is desirable as the digestibility will be higher.

• As an alfalfa plant matures, quality decreases as the percentage of ADF and NDF increase and CP decreases. Acid detergent fibre is correlated to the digestibility of the forage and the NDF level can be used to predict DMI. For every percent increase in ADF, digestible dry matter (DDM) decreases 3 to 4 percent.

• The relative feed value (RFV) index was developed to rank forages by calculating the potential digestible dry matter intake. The index is used to allocate forages according to livestock nutritional needs. For example, a milking dairy cow requires alfalfa hay with a RFV greater than 150. Whereas a beef cow requires a lower quality forage with a RFV of 100.

• Harvest management affects the quality of the alfalfa forage. Cut, cure, bale, transport and store the forage to to prevent leaf loss and maintain it's high quality. Leaves make up about 70% of the nutritive value.

• The primary advantage of making alfalfa silage or haylage is that leaf loss is generally less than 20%. With good haying practices it is normal to lose 40% of the leaf material. If the forage is rained on, raked and then baled, leaf losses of up to 60% can occur.