ISIS Report 13/12/03
Animals Avoid GM Food, for Good Reasons
Experimental and anecdotal evidence shows that animals seek to avoid
GM food and do not thrive if forced to consume such food. Dr Eva Novotny
In the course of preparing a submission to the public hearing on a
genetically modified (GM) maize that the UK government wanted to put on the
National Seed Register, I had the opportunity to review evidence on how animals
respond to GM food. The evidence makes interesting reading.
Chardon LL experiments
Chardon LL is a GM maize engineered for tolerance to the herbicide
glufosinate. The whole plant is intended as cattle-feed, but no experiments on
whether this is safe or suitable has been carried out.
Approval of the application of Aventis for commercial growing of this
maize in the UK was granted on the basis of two animal-feeding experiments, one
on feeding kernels to chickens and the other on feeding the isolated GM protein
to rats. In both experiments, the investigators concluded that the tested
animals consumed food and gained weight normally.
However, reanalysis of the data led to a different conclusion.
The first experiment fed Chardon LL maize kernels to 280 young broiler
chickens over 42 days, purportedly to detect differences in nutrient quality of
corn samples. All the chickens were allowed to eat at will.
The official report said: Results of live bird traits
that source of corn
had no effect on body weight, feed intake,
percent mortality over the experimental period
Glufosinate tolerant corn from the U.S.A. is comparable in feeding value,
for 0-42 day broilers, relative to the commercially available corn hybrid.
Therefore, the nutritive value of glufosinate tolerant corn hybrid is
equivalent to a commercially available corn hybrid. The mortality rate
was judged to be normal.
Closer examination of the data shows up many unexplained anomalies.
Although chickens on the GM diet have, on average, weights only 1% below
the average weight in the control group, the error bars are much wider for
chickens fed GM maize; and they grow progressively wider as the experiment
During the first phase of the experiment (days 0-18), the test group
eating GM maize consumed 9 gm more than the control group; during the second
phase (18-32 days), consumption had dropped to 7 gm less; and in the final
phase (days 32-42) consumption by the test group had fallen to 63 gm less than
that of the control group. Again, the error bars are much greater for the test
group and increase with time.
Average body weights and feed intakes of the chickens do not vary
significantly, as concluded in the study. Nevertheless, the much larger error
bars for both these quantities give concern that the weight gains and the
feeding patterns were erratic in the treated group, indicating that at least
some of the chickens were not thriving on the glufosinate-resistant maize.
Information on deaths during the study is given only in the form of
mortality: 7.14 ± 5.47 % for chickens eating the glufosinate-resistant
maize and 3.57 ± 4.29 % for those fed commercial hybrid corn. Although
the former values are twice those of the latter, the study points out that
values of 5 to 8 % in male broilers are normal at that laboratory.
Nevertheless, it may be significant that the mortality rate was twice as
high among the chickens eating the GM maize as compared with those fed
commercial non-GM hybrid maize.
Another experiment involved feeding PAT-protein to rats. This study on
rats, like that on chickens, has little relevance to cattle, as the digestive
systems of these animals are very different. Furthermore, it was not the
Chardon LL maize itself, but the isolated PAT-protein it contains that was
tested; and the effects of feeding the isolated protein must be expected to
differ from the effects of feeding the whole maize.
Also, the very short time during which the experiment was pursued (14
days) gives no indication of possible long-term effects of feeding over a
lifetime, especially when the maize is to be fed to a very different animal
species. Only five male rats and five female rats were used in each of the four
groups, and the individual rats had substantial differences in weight even at
the start of the experiment.
Nonetheless, the studies claimed, Average mean food consumption
over treatment was in the same range for treated groups and controls,
Occasionally recorded differences between controls and treated groups
were generally small, showed no dose-relationship or consistent
and Mean body weights were similar for treated groups
and controls. There were no differences which could be attributed to treatment
with the test article.
Although the purpose of the study was to test for toxicity, the data
provide evidence that the animals may not be thriving on a diet including the
PAT-protein. The evidence for this suggestion comes from data on body weights
and food consumption.
The 40 young, rapidly growing rats were divided into two control groups
and two test groups, each containing 5 males and 5 females. All animals were
allowed to eat at will.
Tables provided, separately for males and females, the average weight of
each of the four groups as measured on several days of the experiment. For
males eating a small amount of PAT-protein, weights remained nearly the same as
for one of the control groups; while for those eating the high dose of
PAT-protein, weights fell progressively below those of all other groups, even
though these rats were marginally the heaviest group at the beginning of the
experiment. Females in both groups consuming PAT-protein had weights falling
gradually below those of the two control groups, although the females fed the
high dose were the heaviest group at the beginning. For both males and females
consuming high-doses of PAT-protein, weight gain per day, averaged over the
duration of the experiment, was distinctly lower than for either control group.
During the latter half of the experiment, data for individual animals
show that 2 males and 2 females on the low-PAT-protein diet were rapidly
falling behind in weight as compared with other rats in the same group and in
both of the two control groups. Of the rats on the high-PAT-protein diet, 3
males and one female were falling behind in weight during the latter half of
While these data are not conclusive because too few animals were studied
over too short a time, the low rates of weight-gain in several of the animals
eating PAT-protein suggest that some individuals were not thriving on the diets
that included PAT protein.
The data also showed unusual patterns in the food intake, averaged over
the group, of animals consuming the high dose of PAT-protein, suggesting that
the diet did not suit the rats. In the middle of the experiment, both males and
females on this diet had an increase in food intake followed by a dip, unlike
the other groups; then, over the last five days, their food consumption showed
a sharp rise, again unlike other groups.
Stray cattle did not eat GM maize
The following press release -Damage To Gm Maize National List
Trial Site - was issued by the then Ministry of Agriculture, Fisheries
and Food on November 10, 2000:
The NIAB (National Institute of Agricultural Biotechnology) have
notified MAFF of damage to a national list trial of GM forage maize taking
place in Somerset. The damage was caused by cattle straying onto the site in
October. There is no evidence that the cattle ate any of the maize.
Sheridan - the maize in question - has full approval under
European GM legislation to be marketed for both animal and human food use. The
undamaged maize at the site has since been harvested.
Sheridan is a GM forage maize that contains the same genetic construct
(conferring herbicide tolerance) as Chardon LL. It is interesting to note that
the cattle did not wish to eat any of the maize.
When the Corn Hits the Fan
American journalist Steven Sprinkel wrote an article with the above
title in an ACRES, USA Special Report dated 19 September, 1999 (reproduced on
the Natural Law Party Wessex website,
which contains the following excerpt.
After four months of retrieving anecdotes from Kansas to
Wisconsin, I think its high time to sample the producer community more
thoroughly to see how many stories are out there. About the hogs that
wouldnt eat the ration when the GMO crops were included. About the farmer
who said Well, if you want your cattle to go off their feed, just switch
them out to a GMO silage. About the farmer who said that his cattle broke
through an old fence and ate down the non-GMO hybrids but wouldnt touch
the Round-up ready corn, and as a matter of fact They had to walk through
the GMOs to get to the Pioneer 3477 on the other side. About the
cattleman who saw the weight-gain of his cattle fall off when he switched over
to GMO sources. About the organic farmer with a terrible deer problem on his
soybeans, and when he drives out at night there are forty of them mowing down
his tofu beans while across the road there isnt one doe eating on the
Round-up Readies. About the raccoons romping by the dozen in the organic corn,
while down the road there isnt one ear thats been touched in the Bt
fields. Even the mice will move on down the line if given an alternative to
these crops. What is it that they know instinctively that most of
Other incidents of cattle refusing to eat Bt maize
Various scientists working actively with the farming community in the
United States have reported difficulties feeding GM maize to cattle. In April
2000, one of them (who has asked to remain anonymous) sent the following
There have been dozens of such reports over the last two years.
Generally, the reports are concerned with Bt maize. Many farmers feed maize to
their cattle just as it grows, without mixing in other feedstuffs. Typical
reports are that the farmer buys a new shipment of maize, which his cattle
either refuse to eat or eat with reduced consumption. Upon making enquiries, he
discovers that the maize is a genetically modified variety. When he replaces it
with a non-modified maize, the cattle start eating again.
Scientific evidence for animal preferences
Although it may be difficult to credit animals with the ability to
distinguish between GM and non-GM feed, this anecdotal evidence is supported by
scientific evidence that they can indeed distinguish between organically- and
non-organically-produced feed; moreover, they have a definite preference for
the former (see Do animals like good food? this issue).
Re-analysis of experiments on chickens and on rats fed Chardon LL GM
maize suggest that, contrary to the official conclusions, at least some
individual animals do not gain weight as rapidly as they should when given a
diet including GM feed. Furthermore, there appear to be irregularities in the
feeding habits of at least some animals given GM feed. In the experiment on
chickens, mortality was twice as high among those fed the GM maize as among
those fed non-GM maize.
Existing scientific evidence indicates that farm animals prefer
organically produced over conventionally produced feed; while a substantial
amount of anecdotal evidence on both domestic and wild animals indicates that,
given a choice, they will avoid GM feed and, if forced to eat GM feed, they do
(This is an edited version of Report for the Chardon LL Hearing:
Non-suitability of genetically engineered feed for animals, by Eva
Novotny, Scientists for Global Responsibility, May 2002.)