facilitated recurrent selection A type of recurrent selection in which genetic male sterility is maintained in the population to maintain heterozygosity and genetic diversity and to permit the recombination and shifting of gene frequencies.

fast-release fertilizerSee quick-release fertilizer.

fat-free body weightSee body weight, fat-free.

feed forward The effect of process inputs (the levels of factors entering into a process) on the process rate. In positive feed forward, the inputs amplify the rate; in negative feed forward, they diminish the rate. Compare feedback.

feeding value (1) Characteristics that make feed valuable to animals as a source of nutrients. (2) The combination of chemical, biochemical, physical, and organoleptic characteristics of forage that determine its potentials to produce animal meat, milk, wool, or work. Considered by some as synonymous with nutritive value. See also forage quality.

fermentation Large-scale culture of cells suitable for recovery of cell products, including various chemical or pharmaceutical compounds, or biomass.

fertigation The application of fertilizer through an irrigation system.

fertilizer burnSee foliar burn.

fescue foot Red and swollen skin at junction of hoof of animals grazing tall fescues, followed in advanced stages by gangrenous sloughing off of hoofs, tail tips, and ear tips, along with loss of appetite and emaciation. Problem is most severe in cold, rainy, or overcast weather.

fescue toxicity (1) Exposure of an animal to the endophyte-infected tall fescue plant, eliciting a toxic response in the animal. (2) The state of being toxic to the animal. Usage: Dosage or effect on the animal are implied. Not synonymous with fescue toxicosis.

fiber (1) A long, thick-walled cell (e.g., in cotton) serving to strengthen an organ. (2) A unit of matter characterized by a length at least 100 times its diameter or width.

fiber fineness A relative measure of size, diameter, linear density, or mass per unit length of fiber, expressed in a variety of units.

fiber length distribution A graphic or tabular presentation of the proportion or percentage of fibers having different lengths.

fiber, textile A generic term for the various types of matter that form the basic elements of textile fabrics and other textile structures.

fibrograph test beard The portion of a test specimen (e.g., of cotton) that has been combed into a beardlike shape and that protrudes from the outside of a pair of fibrograph combs.

field burning Burning plant residue after harvest to (i) aid in insect, disease, and weed control; (ii) reduce cultivation problems; and (iii) stimulate subsequent regrowth and tillering of perennial crops.

fines Material that passes through a screen whose openings are smaller than the specified minimum size of the product being processed.

fistula A surgical opening, duct, or passage from a cavity or hollow organ of the body.

fixed stockingUsage: Not a recommended term. See set stocking.

flail mower A mower that cuts turf by impact of blades rotating in a vertical cutting plane relative to the turf surface. See impact mowing.

flavor The simultaneous physiological and psychological response obtained from a substance in the mouth that includes the senses of taste (sweet, sour, salty, bitter), smell (fruity, pungent), and feel. The sense of feel as related to flavor encompasses only the effect of chemical action on the mouth membranes, such as heat from pepper, coolness from peppermint, and the like. No reliable correlation of taste with chemical structure has yet been possible. Flavor is a critical factor in the acceptability of foods, medicines, confectionery, and beverages.

flint Maize variety with very hard kernels. Compare dent.

flip-flop grazingUsage: Not an acceptable term. See alternate grazing.

flowering stage The physiological stage of a grass plant in which anthesis (blooming) occurs, or flowers are visible in nongrass plants.

flush Growth that is produced during a short period.

fodder Coarse grasses such as corn and sorghum harvested with the seed and leaves green or alive, then cured and fed in their entirety as forage.

fold-back The double-stranded structure formed by intrastrand reassociation between inverted repeat sequences present in the same DNA strand.

foliar burn Injury to shoot tissue caused by dehydration due to contact with high concentrations of chemicals (e.g., certain fertilizers and pesticides).

foot printing, wilt Temporary foot impressions left on turf when flaccid leaves of grass plants suffer incipient wilt and have insufficient turgor to spring back after being stepped on.

forageFor other entries, see also available forage; stockpiling forage.

forage allowance The relationship between the weight of forage dry matter per unit area and the number of animal units or forage intake units at a given time; a forage-to-animal relationship. The inverse of grazing pressure. Usage: For a more specific term, substitute herbage or browse for forage.

forage intake unit An animal with a rate of forage consumption equal to 8 kg dry matter per day. Usage: Assuming that one animal unit has a dry matter intake rate of 8 kg per day, any animal may be represented as a certain fraction or multiple of the animal unit, based solely on its rate of forage intake per day. An animal that has a forage intake rate larger or smaller than 8 kg dry matter per day will have an animal-unit-equivalent that is a proportionate fraction or multiple of one animal unit. In a publication, the term forage intake unit should be followed by a description in a standard format, including at least the following: forage species and cultivar, stage of growth, plant height, and forage mass.

forage nutritive valueSee nutritive value.

forb Any herbaceous broadleaf plant that is not a grass and is not grasslike. See also legume.

forestland Land on which the vegetation is dominated by forest or, if trees are lacking, the land bears evidence of former forest and has not been converted to other vegetation.

form An infraspecifc taxon in botanical nomenclature, below the rank of variety. Abbr.: f. Usage: The abbreviation in roman type; the name, in italics; no capitals. Compare forma specialis.

forward creep A method of creep grazing in which dams and offspring rotate through a series of paddocks with offspring as first grazers and dams as last grazers. A specific form of first-last grazing.

foundation seed Foundation seed is the progeny of breeder, select, or foundation seed handled to maintain specific genetic purity and identity. Production must be acceptable to the certifying agency.

Fpasture, rotation Pastureland used for a few seasons and then plowed for other crops.

fractionation Separation into components, as by distillation, crystallization, or physical separation.

frame-shift mutation Mutation involving a change in the reading frame.

frequency of clip Distance of forward travel between successive cuts of mower blades.

frontal grazing A grazing method that allocated forage within a land area by means of a sliding fence that livestock can advance to gain access to ungrazed forage.

full (rumen content) Amount of ingested feed or water present in the rumen.

fungusUsage: Too vague to be an acceptable term for the fungus Acremonium coenophialum living symbiotically in tall fescue. Similarly, 'fungal absence', 'fungal incidence', 'fungal presence', 'fungus-free', and 'fungus-infected' are too vague without the context clearly specified.

fusion Joining of the membrane of two cells, thus creating a daughter cell that contains the nuclear material from parent cells. See also protoplast fusion.