Steve and others: An interesting group of papers from a group of USDA
researchers in Idaho deals with how cattle "choose" which herbage to consume.
I am following up on this in an orchardgrass grazing trial at Guelph, and will
share the sense of it here. I think it may pertain to the above thread on
mice and corn, and perhaps, to the Steve Sprinkel (Acres) article on anecdotal
evidence of rejection of GM plants and grain by grazing and fed livestock.
If you ever watch cattle grazing, you'll note that they don't run their tongue
back and forth over the herbage to select which bits to chomp. They move
their muzzle back and forth, suggesting to the Idaho researchers that
volatiles or aromatics could be the cueing agent. Their specific focus was
tall fescue (TF), and a new high-Mg cultivar of TF which they had just bred.
They did a cafeteria-style trial just to compare the apparent palatability of
the new cultivar with other existing cultivars. They controlled for maturity,
and all materials were endophyte-free.
Still, they found consistent and repeatable differences among cultivars in
"disappearance" (how fast the herbage was consumed, when stock had a choice
among several cultivars). They analyzed a large number of volatiles, and in
fact, found 1 or 2 that were positively correlated, and 1-2 that were
negatively correlated, with disappearance (palatability). Fascinating stuff,
with real potential to provide herbage breeders with a trait they can select
for, perhaps to enhance preference/intake. I don't have the refs in front of
me, but one author was Hank Mayland. The work was published in Agronmy
Journal, several years ago (94 or 95), as well as in food sci/chem-type
When reviewing the literature, I noted that this phenomenon on aromatics as
cueing agents is very well established in the insect world. Apparently,
insects can select down to the cultivar level, based on aromatics.
Larry Phelan and colleagues here at the OARDC in Ohio have published work
comparing insect damage on crops grown in organic vs. conventional soils.
Related work was done by Laurie Drinkwater at Davis, on tomatoes, using soil
from about 20 pairs of conv. and org farms.
Based on these sorts of studies, it does not seem to me to be too much of a
stretch to hypothesize that production methods, including mineral nutrient
balance and soil "health" (e.g. disease suppressive soils, microbial
populations, etc.), could influence the attractiveness of plant material to
herbivores - including mice and cattle. By the same token, insertion of
transgenes could also alter the aromatic emanations from herbage, affecting
This would be a readily testable hypothesis, if anyone has the money and
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