An acid quality or state. Solutions with pH below 7.0 show acidity. Acid is the opposite of alkaline or basic. An acid compound yields hydrogen ions when dissolved in water.

Acid Detergent Fiber (ADF)

The highly indigestible portion of the forage (lignin, cellulose, silica) is called acid detergent fiber. ADF is generally used to calculate digestibility and energy. Forages with a high ADF level have a lower digestibility and lower energy than forages that have low levels of ADF.

Adventitious Roots

Roots originating from the nodes at the base of the tillers and the nodes of rhizomes and stolons, which become the dominant root system for the grass. Grasses have mainly adventitious roots.


Residual or regrowth of forage produced after haying or grazing. Aftermath growth is sometimes grazed in the fall, after plants have become dormant.


An alkaline soil is one with a pH above 7.0, the opposite of acidic.


Alkaloids are amines or organic compounds produced naturally by some forage species. Alkaloids can cause poor palatability and potential toxicity of some grasses for livestock. Some grasses such as reed canarygrass have varieties with high levels of alkaloids. Newer varieties of reed canarygrass have low levels of alkaloids.


Allelopathy is the harmful effects of one plant on another plant by the release of chemicals from plant parts through leaching, root exudation, volatilization, residue decomposition, etc. These actions are a process a plant uses to keep other plants from growing too close to it.

Animal Units (AU)

An animal unit is based on forage consumption by a 454 kg (1,000 lb) cow with or without a calf. An animal unit month (AUM) consumes approximately 380 kg/month (840 lb/month) of forage based on a daily consumption of 13 kg/day (28 lb/day).

Animal Unit Equivalent (AUE)

The animal unit is adjusted for other animals by adjusting for animal type, class or size and is given animal unit equivalents (AUE). This figure adjusts for animal weight and intake. A 454 kg (1,000 lb) cow with or without a calf is one animal unit and a yearling heifer 300 kg (700 lb) has an animal unit equivalent of 0.67.


Plants that germinate, establish, flower, set seed and die in one growing season.


In forage, the term means having a negative effect on daily intake, productivity or health of livestock.


An appendage located at the base of the grass leaf blade where the blade is attached to the sheath. Auricles are generally paired, arising from opposite margins of the leaf, may be rudimentary or claw-like and may wrap around the stem until the pairs overlap.


Autotoxicity is a type of allelopathy where a species, through the production of chemicals that escape or are released into the soil, directly inhibits the growth of that same species. Alfalfa autotoxicity is the process in which established alfalfa plants produce a chemical or chemicals that escape into the soil. This chemical prevents the establishment or reduces the growth of new alfalfa plants if seeded too soon following an old stand or if trying to no-till new alfalfa seed into an established alfalfa field.


A slender bristle, usually found projecting from the back or tip of a lemma (outer seed coat) or glume. Awns can be short or long and are sometimes called beards.


The upper angle between a branch or leaf where it is attached to the stem.