Sleper D A, Vogel K P, Asay K H, Mayland H F
Dept. of Agron., University of Missouri, Columbia 65211.
J Anim Sci. 1989 Dec;67(12):3456-62. doi: 10.2527/jas1989.67123456x.
Plant breeders developing cultivars to minimize the hazards of grass tetany are concentrating largely on increasing herbage Mg concentrations in cool-season (C3) grasses. Significant genetic variation has been found for Mg, Ca and K concentrations within C3 grass species studied to date. For most C3 forage grass species, heritability estimates are highest for Mg, slightly lower for Ca and lowest for K concentrations. The largest genotype x environmental interactions are found for K values, whereas small environmental effects have been observed for Mg and Ca values. No C3 forage grass cultivar has been developed to date that would eliminate hypomagnesemia. Grass breeders need to develop more experimental C3 plant populations that have high Mg and Ca concentrations. These experimental synthetics with genetically altered mineral concentrations need to be fed to ruminants susceptible to grass tetany to determine whether grass tetany can be eliminated or reduced. Limited feeding trials using ruminants show that improved animal performance can be expected when feeding forage grasses bred for higher Mg concentrations.
致力于培育能将草痉挛危害降至最低的品种的植物育种者，主要精力集中在提高冷季（C3）草类牧草中的镁含量上。在迄今研究的C3草种中，已发现镁、钙和钾含量存在显著的遗传变异。对于大多数C3饲草种类，镁含量的遗传力估计值最高，钙含量略低，钾含量最低。钾值的基因型与环境的相互作用最大，而镁和钙值的环境影响较小。迄今为止，尚未培育出能消除低镁血症的C3饲草品种。草类育种者需要培育更多镁和钙含量高的实验性C3植物群体。这些矿物质浓度经过基因改变的实验性合成物需要喂给易患草痉挛的反刍动物，以确定是否可以消除或减少草痉挛。使用反刍动物进行的有限饲养试验表明，饲喂镁含量较高的培育饲草时，有望提高动物性能。
