Agriculture Reference
In-Depth Information
throughout their whole lives or only on a
short-term (less than 90 days), or long-term
(more than 90 days), basis, but in both cases
these animals were bred to produce future
generations (studies performed on two to
ten generations). Further details can be
found in Snell
et al
. (2012). Farm animals
(dairy cows, bulls, goats, pigs, sheep, hens
and quails) or rodents were used (see
Chapter 5). Parameters measured included
body weight, feed intake, detection of DNA
from the GM plant in animal organs,
enzyme concentrations or activities and
some reproductive parameters. h e main
goal of these studies was to assess whether
feeding a generation (
n
) with a GM-based
diet had adverse ef ects on subsequent
generations (
n
+
x
). h e studies presented in
Table 8.2 concern feeding studies with i rst-
generation GM plants with agronomic traits
(see Chapter 6); one study used
a plant line with an output trait (see
Chapter 7).
et al
. (2010) fed pellets containing 20%
control triticale or 20% glufosinate-tolerant
triticale to mice for i ve consecutive
generations and found some changes in
lymph nodes and in immune response
(increased IL-2 levels and decreased IL-6
levels) in the i fth generation. Trabalza-
Marinucci
et al
. (2008) and Tudisco
et al
.
(2010) reported some minor metabolic
changes when comparing glyphosate-
tolerant soybean and Bt maize, respectively,
to their control. h e results of the latter
study did not demonstrate any health
hazards, but the authors suggested that
these changes should be investigated
further. It would be particularly interesting
to know whether or not these changes were
reproducible.
In target animals, Buzoianu
et al
. (2012b)
specii cally examined pig of spring at birth,
while the publication of the same team
(2012c) examined pigs for 115 days post-
weaning. Interestingly, the longest multi-
generational study consisted of feeding
laying quail with a diet containing up to 50%
Bt maize over ten generations. Bt maize did
not inl uence signii cantly the production
and reproductive performances of animals
compared with animals fed a diet containing
50% isogenic maize. Unfortunately, further
multi-generational studies using food-
producing animals are missing (Flachowsky
et al
., 2012).
It should be highlighted that some of
these studies suf er from serious weaknesses
such as lack of an appropriate control group
(see Table 8.2), which could be the main
reason for the observed dif erences.
Statistical criticisms of these studies can
also be raised, especially as the EFSA (2010)
have underlined the necessity for an
improved methodology when statistics are
involved: poor dei nition of a control (or
group control), weak dei nition of factor
levels, lack of a complete combination of
factors inside experimental designs, no
evaluation of the statistical power, as well as
too few multivariate approaches, are
weaknesses that have often been observed
in these studies.
What can be learned from multi-generational
studies?
Multi-generational (or trans-generational)
studies (most of them over several
generations) were carried out to test the
inl uence of GM feed on reproduction, long-
term health and metabolic ef ects in
laboratory and target animals. In laboratory
animals, no negative ef ects were described
for growth, testicular cells or reproductive
traits in mice fed Bt maize, a glyphosate-
tolerant soybean or a transgenic triticale
grain tolerant to the herbicide, glufosinate,
when compared with conventional maize,
soybean or triticale (Brake and Evenson,
2004; Brake
et al
., 2004; Baranowski
et al
.,
2006). Rats and their of spring were not
inl uenced signii cantly in a i ve-generation
study if fed 5% GM glufosinate-tolerant
potatoes or conventional potatoes (Rhee
et
al
., 2005). Kiliç and Akay (2008) found no
dif erences in the organ weights of the
of spring and no dif erences in the
reproduction rates of rats fed up to 20% Bt
maize or conventional maize. Krzyzowska
