Chemical Composition of Agropyron desertorum as Related to Grass Tetany

Mayland, H.F. and Grunes, D.L. and Stuart, D.M. (1974) Chemical Composition of Agropyron desertorum as Related to Grass Tetany. Agronomy Journal. 66(3):441-446.

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Abstract

Grass tetany, a Mg deficiency of ruminants, accounts
for significant economic losses to Western cattlemen during
the spring grazing period on Agropyron desertorum.
This nutritional deficiency may also occur when ruminants
graze other temperate grasses, but the soil-plant-animal
factors leading to the problem are not well understood.

The objective of this study was to provide definitive
data relating seasonal changes in the chemical composition
of forage to the occurrence of grass tetany on semiarid
grasslands.

The field experiment was established on two calcareous
soils where grass tetany had previously occurred. Agropyron
desertorum forage was harvested from both sites
at regular intervals during the spring tetany period in
each of 5 years. The forage samples were analyzed for
mineral elements, N, total water-soluble carbohydrates
(TWSC), higher fatty acids (HFA), ash alkalinity, and
aconitic acid.

High levels of N and HFA, which are known from
other studies to reduce Mg availability to the animal,
coincided with the occurrence of tetany. The low Mg
concentrations measured in the forage probably provided
only marginal levels of available Mg to the grazing
animals. A rapid increase in the ratio of N/TWSC coincided
with the onset of tetany, and may be the primary
factor which indirectly decreases Mg availability and
precipitates the occurrence of tetany. Although the relationship
of the protein/energy imbalance to grass tetany
has been suggested previously, as far as the authors are
aware this is the first time that N/TWSC values obtained
during the growing season have been documented in conjunction
with the occurrence of grass tetany.

Item Type:	Article
NWISRL Publication Number:	0268
Subjects:	Irrigated crops > Grass forage > Chemistry Mass Import - autoclassified (may be erroneous)
Depositing User:	Dan Stieneke
Date Deposited:	20 Nov 2010 21:51
Last Modified:	16 Feb 2017 22:04
Item ID:	248
URI:	https://eprints.nwisrl.ars.usda.gov/id/eprint/248