Submitted to: Arnel Hallauer International Symposium on Plant Breeding
Publication Type: Book / Chapter
Publication Acceptance Date: March 15, 2005
Publication Date: August 18, 2006
Citation: Casler, M.D. 2006. Breeding for increased forage quality. In: Lamkey, K.R. Lee, M., editors. Plant Breeding: Arnel Hallauer International Symposium. Oxford, UK: Blackwell Publishers. p. 323-334. Technical Abstract: Plant breeding is an extremely cost-effective mechanism for increasing the nutritional value of forage crops. Genetic gains in in vitro dry matter digestibility (IVDMD) have averaged 0.7 - 4.7% year-1, similar to long-term gains for grain yield of many cereal crops. Relatively small increases in IVDMD typically result in measurable improvements in animal performance. Gains in IVDMD result from changes in chemical, anatomical, and/or morphological traits of plants, but rarely from genetic shifts in timing of reproductive maturity. These genetic gains are both genetically and environmentally stable and, for perennial forage crops, require only a one-time investment by growers. Selection for increased forage nutritional value is often associated with reductions in agricultural fitness traits, such as forage yield, disease and/or insect resistance, and stress tolerance. These characteristics can often be corrected by concomitant selection pressure in field-oriented plant breeding programs. Transgenic plants represent a new mechanism for generating novel phenotypes with improved forage nutritional value. Many of these phenotypes appear to represent metabolic lesions that may also occur by natural mutations, but are more frequent within transgenic populations. Transgenic technology appears capable of contributing novel phenotypes to improved forage cultivars, but only from collaboration between molecular biologists and plant breeders or agronomists with strong field-oriented programs.