Agriculture Reference
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Table 6.6. Performance and some metabolic parameters of the fi rst and second lactation of a long-term
feeding study with dairy cows ( n = 18 per treatment, 25 months with Bt maize (MON 810, 63% of
roughage, 41% of concentrate from maize). a (From Steinke et al ., 2010.)
Lactation of
experiment
First
P level
Second
P level
Isogenic
Transgenic
Isogenic
Transgenic
Dry matter intake
(kg/day)
Milk yield (kg/day)
Milk fat (%)
Milk protein (%)
NEFA (μmol/l)
BHBA (mmol/l)
AST (U/l)
GLDH (U/l)
-GT (U/l)
0.532
0.566
0.015
<0.001
0.991
0.107
0.263
0.922
0.426
18.7
23.9
3.95
3.62
287
0.46
92.6
19.5
23.2
18.9
23.7
4.03
3.71
281
0.44
89.8
19.1
23.9
21.0
29.2
3.75
3.59
292
0.50
94.3
13.8
23.5
20.4
28.8
3.86
3.56
290
0.49
88.8
16.1
23.9
0.080
0.419
0.055
0.299
0.988
0.304
0.177
0.178
0.575
Notes: a No fragments of Cry1Ab DNA in blood, milk, faeces and urine of cows; traces of Cry1Ab protein were detected
in faeces, but not in blood, milk and urine (Guertler et al ., 2008, 2009). AST = aspartate-amino-transferase; BHBA =
beta-hydroxy butyric acid; GLDH = glutamate-dehydrogenase; -GT = gamma-glutamyl-transferase; NEFA = free fatty
acids.
reported for the uterus weight (0.10 and
0.12% of the body weight, respectively, for
non-GM- and GM-fed animals) and the rate
of severe stomach inl ammation. h is is the
i rst and only report on changes in organ
weight and adverse i ndings on gross
pathology. Further studies should describe
materials and methods better from the
nutritional point of view and should pay
more attention to such end points.
Apart from zootechnical parameters
(e.g. feed intake, animal yield, feed
conversion rate, composition and quality of
food of animal origin), some authors also
investigated the metabolic parameters in the
animal, as shown, for example, in a 2-year
study of dairy cattle fed with a high portion
of Bt maize (Table 6.6). h e higher milk
protein content in the i rst lactation of cows
fed with Bt maize was the only one signii cant
result, but this result should not be
overestimated because of other ef ects in
the second lactation and its biological
relevance (EFSA, 2011b).
Based on the results mentioned
previously, the necessity of animal feeding
studies with feed from i rst-generation GM
plants is often questioned with regard to
their importance and their scientii c yield.
According to various guidance documents
(e.g. EFSA, 2006, 2008, 2011a), such studies
are not urgently needed. No animal feeding
studies are required if the dif erences in
compositional analyses between isogenic
and transgenic plants are small or negligible
(plants are substantially equivalent; i rst-
generation GM plants) because of the costs
of such studies and the reduction in the
numbers of experimental animals.
On the other hand, feeding experiments
with i rst-generation GM plants with target
animals may contribute to demonstrating
the nutritional equivalence and the safety of
the feed to the public, and therefore the
experiments could improve the public
acceptance of GM feed. Furthermore,
recommendations for optimal amounts in
target animal feeding may be deduced.
All animal feeding studies described in
peer-reviewed journals and summarized
above show that feeds from i rst-generation
GM plants which are assessed by a scientii c
body with responsibility for regulating
food/feed safety (e.g. EFSA, FDA, USDA)
are as safe as or safer than crops produced
with traditional methods. About 10 years
ago, Chassy (2002) came to the same
conclusion that 'after extensive safety
testing and some i ve years of experience
with such crops in the marketplace, there is
not a single report that would lead an
expert food scientist to question the safety
 
 
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