Bovine somatotrophin (BST) - a.k.a. bovine growth hormone, this protein is found naturally in cattle, and is the bovine counterpart of human growth hormone, one of the earliest biopharmaceutical products. It has been cloned, using recombinant DNA technology, expressed in large amounts and marketed as an agricultural product to improve the growth rate and protein:fat ratios in farm cattle, and to improve milk yield. Its use is banned in some countries

Breed - noun: in AnGR, either (i) a sub-specific group of domestic livestock with definable and identifiable external characteristics that enable it to be separated by visual appraisal from other similarly defined groups within the same species or (ii) a group of domestic livestock for which geographical and / or cultural separation from phenotypically similar groups has led to acceptance of its separate identity. cf breed at risk; breed not at risk; critical breed; critical maintained breed; endangered-maintained breed

Brewing - the process by which beer is made. In the first stage the barley grain is soaked in water and allowed to germinate (malting), during which the natural enzymes of the grain convert the seed starch to maltose, and then to glucose. Grain is then dried, crushed, and added to water at a specific temperature (steeping) and any remaining starch is converted to sugar. The resulting liquid (wort) is the raw material to which yeast is added to convert sugar to alcohol. Hops (female flowers of Humulus lupulus) are added during this process to give a characteristic flavour

Bridge - a filter paper or other substrate used as a wick and. support structure for a plant tissue in culture when a liquid medium is used

Broad host range plasmid - a plasmid that can replicate in a number of different bacterial species

Broad sense heritability - in quantitative genetics, the proportion of the total phenotypic variation due to genetic variation

Browning - discoloration due to phenolic oxidation of freshly cut surfaces of explant tissue. In later stages of culture, such discoloration may indicate a nutritional or pathogenic problem, generally leading to necrosis

Bubble column fermenter - a fermentation vessel, or bioreactor, in which the cells or micro organisms are kept suspended in a tall cylinder by rising air, which is introduced at the base of the vessel

Bud - a region of meristematic tissue with the potential for developing into leaves, shoots, flowers or combinations; generally protected by modified scale leaves. A terminal (or apical) bud exists at the tip of a stem or branch, while axillary (or lateral) buds develop in the axils of leaves

Bud scar - a scar left on a shoot when the bud or bud scales drop

Bud sport - a somatic mutation arising in a bud and producing a genetically different shoot. Bud sports includes changes due to gene mutation, somatic reduction, chromosome deletion or polyploidy

Budding - 1. a method of asexual reproduction in which a new individual is derived from an outgrowth (bud) that becomes detached from the body of the parent
2. among fungi, budding is characteristic of the yeast Saccharomyces cerevisiae
3. a form of grafting in which a single vegetative bud is taken from one plant and inserted into stem tissue of another plant so that the two will grow together. The inserted bud develops into a new shoot. See grafting

Buffer - a solution that resists change in pH when an acid or alkali is added, or when solutions are diluted

Buoyant density - the intrinsic density which a molecule, virus or sub cellular particle has when suspended in an aqueous solution of a salt, such as CsCl, or a sugar, such as sucrose. DNA from different species has a characteristic buoyant density, which reflects the proportion of G=C base pairs. The greater the proportion of G=C, the greater the buoyant density of the DNA