Genetic variability for elements associated with grass tetany in Russian wildrye

Asay, K.H. and Mayland, H.F. (1990) Genetic variability for elements associated with grass tetany in Russian wildrye. Journal of Range Management. 43(5):407-411.

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Abstract

Grass tetany (hypomagnesemia) may be an important factor
limiting productivity of animals grazing Russian wildrye [Psathyrostachys
juncea (Fisch.) Nevski]. This malady is associated with
relatively low concentrations in the forage of Mg and Ca, and high
values for K and K/(Ca+Mg). We studied the genetic variablity in a
Russian wildrye breeding population for mineral elements that
relate to grass tetany in ruminants. Forty-five progeny lines, established
as spaced plants in a randomized complete block, were
sampled at the pre-boot and boot stages in each of 2 years and
analyzed for Mg, Ca, K, and P. Although seasonal variation was
evident, K/(Ca+Mg) of the progeny lines ranged from 3.2 to 4.6,
well above the 2.2 level at which a 5% incidence of grass tetany has
been found in dairy cattle. With few exceptions, progenies differed
for all traits evaluated. Differences among progenies were relatively
consistent over harvests for all traits. A reduced tetany
potential (RTP) was computed as the sum of normalized Mg and
reciprocal of K/(Ca+Mg) values, providing an estimate of the grass
tetany risk for individual progeny lines. The variation among
progenies, and the magnitude of broad-sense heritability estimates
for RTP (0.48) and K/(Ca+Mg) values (0.31), indicate that mineral
ion composition of this breeding population can be altered through
breeding. The high K/(Ca+Mg) values in the population suggest
that it may be helpful to introduce genetic factors conditioning
lower grass tetany potential from other sources. Intercharacter
correlations suggest that breeding for higher levels of Mg will be
accompanied by increased Ca and, to a lesser extent, increased K.

Item Type:	Article
NWISRL Publication Number:	0715
Subjects:	Irrigated crops > Grass forage > Chemistry Mass Import - autoclassified (may be erroneous)
Depositing User:	Dan Stieneke
Date Deposited:	20 Nov 2010 21:53
Last Modified:	03 Jan 2017 17:14
Item ID:	538
URI:	https://eprints.nwisrl.ars.usda.gov/id/eprint/538