Chemical Characterization and In Vitro Fermentation of Two Forages for Horses

In the UK, the most common dried forage fed to horses is grass hay. Some of this hay has a rather low nutrient value so that horses fed hay-only diets may not be getting enough calories to maintain weight and support exercise. As an alternative to grass hay, some horse owners are looking for other types of conserved forage. One alternative, high temperature dried (HT) alfalfa, provides high-quality protein and energy from digestible fiber. It also contains valuable micronutrients such as calcium, vitamins A and E, and the B vitamins thiamin, riboflavin, biotin, and folic acid.

In a study conducted at Aberystwyth University in the UK, an automated gas production system developed for evaluating feeds for ruminants was used to quantify the fermentation kinetics of ground grass hay (H), high temperature dried chopped alfalfa (A), molassed chopped high temperature dried alfalfa (MA), and ground high temperature dried alfalfa (GA). These four feeds were incubated with an equine hindgut microbial inoculum, and the gas produced during fermentation was monitored for a period of four days. Endpoint dry matter (DM) disappearance of feeds was related to the total gas produced. The total volume of gas was greatest from A > MA > GA >H, while initial rates of gas production were greatest from GA > A > H.

The researchers concluded that horses may get along better on diets containing alfalfa than on hay alone. In addition, this gas production system for evaluating feed may have potential for choosing forages for equines in vitro.