Published July, 2014

Q.Should I look for hay that comes from a fertilized or unfertilized field? In what ways would the nutrition be affected? Does fertilizing the field increase the protein content of the hay? What are appropriate questions to ask regarding the hay?

ROBERTA, CAMANO ISLAND, WASH.

A.Whether or not a hay field is fertilized might be more important to the hay producer than to the hay purchaser.

Fertilization might affect the nutrient content of the hay to some extent, but it might also be needed to keep the plants productive. It can increase yield by tons of hay per year, and it can also keep the plants productive for a longer period of time. Fertilization practices should be individualized for the type of plant and the composition of the soil.

Fertilization with nitrogen can affect the amount of crude protein in the hay, but other factors, such as stage of maturity at harvest, are more important. A very immature plant would be one that is very soft and leafy, whereas a mature plant is more stemmy and might have flowers or seed heads on it. As a plant matures, its nutrient value usually decreases, so hay harvested at a mature stage is less nutritious than hay harvested at an immature stage.

In selecting hay the first thing you should figure out is what your horse's needs are. A young, growing horse requires hay with more nutrients than a mature, inactive gelding, for example. The best hay to purchase is hay that fits the needs of your horse. Another very important item is to make sure that the hay is not moldy or excessively dusty.

Finally, if you are purchasing hay by the bale, be sure to find out how much a bale weighs. A bale that costs $4, but only weighs 45 pounds, is not a better value than a 60-pound bale that costs $5!

Laurie Lawrence, PhD, (equine nutrition), is a professor in the University of Kentucky's Department of Animal Sciences.