Response to Selection for Reduced Grass Tetany Potential in Crested Wheatgrass

摘要: Grass tetany (hypomagnesemia) has caused substantial economic losses in ruminant animals grazing crested wheatgrass (Agropyron spp.) and other cool-season (C3) grasses. This malady is most prevalent early lactating forage that deficient Mg, Ca, carbohydrates with high levels of K. The K/(Ca + Mg) ratio expressed as moles charge often used to estimate the grass potential samples. Previous studies have shown heritable variation exists populations for traits associated tetany, research was conducted determine genetic response selection these traits. Selections were made during 1985 from two breeding Utah ('I-28' 'Hycrest') based on a reduced (RTP) index, which incorporates along concentrations Mean values by 5% I-28 11% Hycrest after one cycle selection. Narrow-sense heritability actual advance parent-progeny regression ranged 0.62 0.82 analyses data combined across sampling dates years (1988 1989). Genetic basis RTP index closely Ca Mg but not Correlations between crude protein content digestibility suggested would likely be accompanied improved quality population.