September 12, 2001 | By: Haven Miller

Forages are the foundation for building rations for the dairy herd. That means hay or balage that is higher in quality will lead to better animal performance and improved milk production.

"Dairy producers looking to buy hay or balage should have it tested before making the purchase," said Donna Amaral-Phillips, Extension dairy specialist in the University of Kentucky College of Agriculture. "Just looking at the hay is not enough to insure top quality."

Energy is the nutrient that most often affects milk production. Cows need adequate amounts of energy to make milk. High quality forages contain more energy, are more digestible, and more palatable to the cow. Forage testing reveals the levels of acid detergent fiber (ADF) and neutral detergent fiber (NDF) in hay or balage, and therefore gives an indication of quality.

To insure adequate samples for testing, Amaral-Phillips recommends that 15 to 20 square bales from each lot be cored using a hay probe. Those core samples should then be mixed in a bucket, and then a quart of the mixed material should be sent to a certified forage testing laboratory.

"When reading a forage analysis, farmers need to look at the relative feed value, or RFV, because this number is an index that reflects the ADF and NDF and compares the sampled hay to what is considered the benchmark for ideal quality," said Amaral-Phillips.

High-producing dairy cows need alfalfa hay, which after harvest contains a relative feed value greater than 150. Hay or balage that tests lower than this will increase feed costs and decrease profitability.

"If we compare the difference in energy supplied by five pounds of hay with an RFV of 150 versus 115, the lower quality alfalfa hay at 115 supports one and a half fewer pounds of milk," said Amaral-Phillips.

Alfalfa hay with an RFV of more than 200 should be fed differently than RFV 150 hay. That's because it contains considerably less fiber than hay with a slightly lower relative feed value. The RFV 200 alfalfa hay acts like concentrates in a milking cow's diet and should be fed along with other forages.

"Farmers should also be aware that with advancing stages of plant maturity, fiber digestibility and protein content of alfalfa decreases while fiber increases," said Amaral-Phillips. "Consequently less energy is available to the cow when it consumes more mature alfalfa hay."

Hay should be purchased based on weight and not size. It should also not contain more than 14 percent moisture or less than 86 percent dry matter. Wetter hays are more prone to molding, and you pay more money for wetter, heavier hay.


Donna Amaral-Phillips, 859-257-7542