A review of the development of a bloat-reduced alfalfa cultivar

Abstract

S. 2000. A review of the development of a bloat-reduced alfalfa cultivar. Can. J. Plant Sci. 80: [487][488][489][490][491]. The studies that led to the development of a bloat-reduced alfalfa began in 1970. Initial work focused on the causes of bloat, the characteristics of bloat-safe and bloat-causing legumes and the development of screening methodologies. The characteristics that were examined as causal factors of bloat in legume species included soluble proteins, saponins, absence of condensed tannins, and rapid breakdown of cells in the rumen. The factor or combination of factors responsible for causing bloat in animals grazing legumes have not been clearly identified; however, of the above, rapid cell breakdown was considered to be the most promising line of research to pursue in selecting a bloat-safe legume. A 4-h nylon-bag rumen digestion technique was developed, which was used to assess the initial rate of digestion (IRD) of fresh leaf material in large numbers of alfalfa genotypes. Using this technique on a population of four alfalfa cultivars, four cycles of recurrent selection for low initial rate of digestion (LIRD) were carried out over an 11-yr period. The resulting selected population, LIRD-4, had a vegetative stage initial rate of digestion that was approximately 85% of that of unselected alfalfa. To determine whether this reduction in IRD would reduce or eliminate bloat, grazing experiments comparing LIRD-4 and unselected cv. Beaver were conducted at three locations over 3 yr. Over all grazings, LIRD-4 caused significantly fewer incidences of bloat than Beaver; thus it is a bloat-reduced, rather than a bloat-safe cultivar. LIRD-4 was released in 1997 and named AC Grazeland Br. Au début, l'accent était porté sur les causes du météorisme, sur les caractères des légumineuses météorisantes et non météorisantes et sur la mise au point de méthodes de tri génétique. Parmi les facteurs causaux éventuels du météorisme, il y avait les protéines solubles, les saponines, l'absence de tanin condensé et la décomposition rapide des cellules végétales dans le rumen. Le facteur ou la combinaison de facteurs responsables du météorisme chez les animaux pâturant des légumineuses n'a pas encore été clairement identifié. Mais de tous ceux énumérés plus haut, c'est la dégradation rapide des cellules dans le rumen qui apparaît comme l'avenue la plus intéressante dans la recherche d'une légumineuse non météorisante. Une technique de digestion ruminale en sachets de nylon pendant 4 heures a été mise au point pour évaluer le taux initial de digestion (TID) des feuilles fraîches provenant d'un grand nombre de génotypes de luzerne. En appliquant la technique à une population de 4 cultivars de luzerne, 4 cycles de sélection récur-rente sur le caractère faible taux initial de digestion (FTID) étaient réalisés dans une période de 11 ans. La population sélectionnée résultante, LIRD-4, démontrait un taux initial de digestion au stade végétatif correspondant à environ 85 % de celui de la luzerne non sélectionnée. Pour déterminer...

Sainfoin production in western Canada: A review of agronomic potential and environmental benefits

“…() reviewed other attempts at genetic modification of CTs in plants, although not in sainfoin specifically, and Coulman et al. ( reviewed research of alfalfa cultivars with reduced bloat potential.…”

“…Technologies available at the time were insufficient; however, bioengineering alfalfa may re-emerge as a solution to bloat issues in ruminants. McMahon et al (1999) reviewed other attempts at genetic modification of CTs in plants, although not in sainfoin specifically, and Coulman et al (2000) reviewed research of alfalfa cultivars with reduced bloat potential.…”

Evaluation of Cicer Milkvetch and Alfalfa Cultivars for Nutritive Value, Anti-Quality Factors and Animal Preference

“…Oxley II (Acharya, 2001) and "Veldt" (Acharya, 2009) are newer cultivars of CMV that have been developed and released in recent years with improved seedling vigour and greater forage yield compared to Oxley. In North America, CMV is an alternative legume to alfalfa (Acharya et al, 2006), therefore in the current study AC Grazeland alfalfa (Coulman et al, 2000) was used as a check (control) forage. There is the expectation that the number of hectares of alfalfa grazed in western Canada will increase, and because of this, producers who want to reduce the risk of bloat occurring in their grazing animals will be interested in CMV cultivars (Coulman et al, 2000).…”

The Occurrence, Biosynthesis, and Molecular Structure of Proanthocyanidins and Their Effects on Legume Forage Protein Precipitation, Digestion and Absorption in the Ruminant Digestive Tract

“…Many characteristic bloat-free legumes contain proanthocyanidins [120,121]. The proanthocyanidin–protein complex decreases the release of protein in the rumen.…”