Agriculture Reference
In-Depth Information
may be expected from the use of the modii ed
crop, specii c crop components or co-
products from GM crops (ILSI, 2007). h e
feeding period should cover the whole
lifespan (see Table 5.3) or a representative
period (e.g. in the case of laying hens or
dairy cows).
of nutrients with GM plants with input
traits (fi rst generation)
h e objective of ei ciency trials is to measure
the ef ect of feed from GM plants on the
performance of food-producing animals and
to compare the results with an isogenic
counterpart and some commercial products.
Many feeding studies have been carried
out during the past years to show the
substantial similarities (OECD, 1993) of
feed derived from i rst-generation GM
plants (without substantial changes in their
composition or GM plants with input traits;
see Chapter 6). Most of the studies were
done as ei ciency trials and GM feed was
compared in adjusted diets with their
isogenic counterparts and some con-
ventional commercial varieties (one to ten
varieties in some cases). h e experimental
designs were done according to the recom-
mendations by ILSI (2003; Table 5.4) and
the EFSA (2006, 2008, 2011a). Questions
concerning the tolerance of some feeds in
animals (tolerance studies to determine the
maximum inclusion level of the feed in
diets) may also be included in ei ciency
trials. Statistical signii cance, but not
biological relevance, is a conl icting subject
in some publications and also with the
public. Recently, the EFSA (2011b,c)
contributed to solving this conl ict and
explored the concept of biological relevance.
It is recommended that the nature and size
of biological changes or dif erences should
5.5.1 Measuring digestibility/
Animal feeding studies play an important
role in testing the nutritional value of the
introduced trait in a nutritionally improved
crop. Analyses of nutrient composition
provide a solid foundation for assessing the
nutritional value of feeds (see Chapter 4);
however, they do not provide information
on nutrient availability.
In the case of substantial changes in plant
composition (GM plants with output traits,
or second-generation GM plants; see Section
5.5.3 and Chapter 7), studies measuring the
digestibility/availability of some nutrients
or nutrient precursors are necessary (ILSI,
2004, 2007; Flachowsky and Böhme, 2005;
EFSA, 2008).
Such studies should be done on laboratory
animals or, preferably, on target animals.
Studies with laboratory animals need less
feed and lower costs (see Table 5.2): some-
times, the application of results to target
animals is questionable, but such studies are
already possible during early plant-breeding
stages.
Table 5.3.
Examples of lifespans for growing/fattening animals (in days).
Conventional/
more intensive
Organic/more
extensive
Animal species/categories
a
Chickens for fattening (broilers)
30-42
56-84
Turkeys for fattening
56-168
70-112
Growing/fattening pigs
150-300
200-400
Veal calves
80-200
-
Growing/fattening bulls
300-500
400-600
Note:
a
Laying hens and dairy cattle are usually used for longer periods. Laying hens:
about 126-140 days for growing (pullets) and about 300-360 days (1 year) for the
laying period. Dairy cattle: about 22-36 months for growing (heifers) and 1-10 years
for lactation (average in Europe, two to fi ve lactations).
