Variation in mineral concentration and grass tetany potential among Russian Wildrye accessions

Variación en la Concentración Mineral y el Potencial de Tétano de Zacates entre Asentimientos de Centeno Silvestre Ruso

Jefferson, P.G. and Mayland, H.F. and Asay, K.H. and Berdahl, J.D. (2001) Variation in mineral concentration and grass tetany potential among Russian Wildrye accessions. Crop Science. 41:543-548.

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Abstract

Grass tetany or hypomagnesemic tetany in cattle (Bos taurus) is
caused by an imbalance of K, Ca, and Mg in the diet. Indications of
grass tetany range from reduced milk yield or weight gain to severe
convulsions and death. The risk of grass tetany dramatically increases
when the K/(Mg + Ca) ratio of forage exceeds 2.2, especially for
dams during early lactation. Russian wildrye [Psathyrostachys juncea
(Fisch.) Nevski], a valuable forage species, has ratios well above this
level. Our objectives were to determine the mineral concentration and
ratio values for 65 accessions of Russian wildrye to select germplasm
sources with low tetany ratio and to determine the effects of year,
location, and their interactions with accessions. Seedlings of each
accession and two checks, Syn A and Mankota, were established in
replicated space-plant nurseries at Logan, UT, Mandan, ND, and
Swift Current, Saskatchewan, Canada. Years-within-location effects
generally produced the largest variance component, while the accession
variance was larger than location x accession and location X
accession x year interaction variances for K, Ca, Mg, KJ(Mg + Ca)
ratio, and Reduced Tetany Potential (RTP) index. Selection for these
traits in Russian wildrye germplasm will require multiple years to
characterize adequately accessions, breeding lines, or synthetics. The
K/(Ca + Mg) ratio of the accessions tested ranged from 2.2 to 3.0
when averaged across sites and years for V4 growth stage. A similar
range of ratio values and ranking of the accessions was observed at
the E2 growth stage. The three tetraploid accessions evaluated were
among the five accessions with the highest tetany ratios. Previously
reported forage yield and seed yield means were significantly correlated
with K, Mg, and N concentrations and K/(Ca + Mg) ratio. The
RTP index was not correlated with forage yield, seed yield, or N
concentration. Therefore, selection in Russian wildrye should be based
on increased RTP index rather than K concentration or K/(Ca + Mg)
ratio to avoid concomitant unintentional selection of reduced forage
yield and seed yield

Item Type:	Article
NWISRL Publication Number:	1041
Subjects:	Irrigated crops > Grass forage > Chemistry Mass Import - autoclassified (may be erroneous)
Depositing User:	Dan Stieneke
Date Deposited:	20 Nov 2010 21:50
Last Modified:	14 Nov 2016 17:30
Item ID:	119
URI:	https://eprints.nwisrl.ars.usda.gov/id/eprint/119