Grass Tetany Hazard of Cereal Forages Based upon Chemical Composition

Mayland, H.F. and Grunes, D.L. and Lazar, V.A. (1976) Grass Tetany Hazard of Cereal Forages Based upon Chemical Composition. Agronomy Journal. 68(4):665-667.

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Abstract

The occurrence of grass tetany in cattle grazing small
grains pastures led us to examine the forage chemical
composition and to suggest the relative risk of grass
tetany to cattle grazing each forage.

Early spring vegetative growth of wheat (Triticum
aestivum L.) and crested wheatgrass (Agropyron desertorum
(Fisch.) Schult) was periodically sampled from 3 x
20 m plots established on a fertile Portneuf silt loam
(Durixerollic calciorthid). In addition, wheat, oats
(Avena sativa L.), barley (Hordeum vulgare L.), and rye
(Secale cereale L.) were grown in pots containing Portneuf
silt loam in the greenhouse and were harvested once while
still vegetative.

Forage samples were freeze-dried and the following
parameters determined: total N (Kjeldahl); NO-₃ (electrode);
Na, K, Mg, and Ca (atomic absorption); S and
Cl (x-ray); P (vanadomolybdate); aconitic acid (polarography);
higher fatty acids and ash alkalinity (both by
titration). Estimated blood-serum Mg values were calculated
from a generally unavailable Dutch nomograph
of forage N x K and Mg values. The nomograph is
included in this paper to enhance its availability.

Wheat forage seemed to pose a greater tetany hazard
than the wheatgrass because wheat had lower values for
Ca and higher values for K, K/(Ca + Mg), aconitic acid,
ash alkalinity, and HCA. The estimated tetany hazard
of the cereal forages was wheat > oats = barley > rye.
This ranking corresponded to the other of blood-serum
Mg levels predicted from the Dutch nomograph. Wheat
forage was lowest in Mg, while rye forage was highest
in Mg and Ca, and lowest in K and N. Aconitic acid
represented a large portion of the total organic acids in
oats, rye, wheat, and wheatgrass, but only traces were
found in barley.

The frequent occurrence of grass tetany in cattle grazing
wheat forage may result because of lower Mg and Ca
levels and higher K, N, ash alkalinity, and HFA levels in
this forage compared to other cereal forages.

Item Type:	Article
NWISRL Publication Number:	0354
Subjects:	Irrigated crops > Grass forage > Chemistry Irrigated crops > Small grain Mass Import - autoclassified (may be erroneous)
Depositing User:	Dan Stieneke
Date Deposited:	20 Nov 2010 21:51
Last Modified:	15 Feb 2017 18:15
Item ID:	304
URI:	https://eprints.nwisrl.ars.usda.gov/id/eprint/304