Feeding Studies with Secondgeneration GM Plants (Output Traits) with Food-producing Animals - Animal Nutrition with Transgenic Plants - page 97

co-products do not vary strongly from their
isogenic counterparts in the composition of
main nutrients (McNaughton et al ., 2008;
Mejia et al ., 2010), but analyses are necessary
of the composition of such co-products (e.g.
stearidonic acids in soybean meal; see
Section 7.3). If GM crops are used for
industrial purposes and they are not suitable
for animal and human nutrition, they should
not enter the food chain or contaminate
feed and food or other crops with their
transgenes (McKeon, 2003). Some examples
of the biofortii cation of various crops will
be described in the following subsections.
In addition, there also exist GM plants
that express specii c proteins for the
prevention of diseases in humans and
animals (Pribylova et al ., 2006), which are
not considered in the following text.

protein sources such as soybeans, either to
increase the protein content (Edwards et al .,
2000) or to change the protein composition
(Falco et al ., 1995; Parsons and Zhang,
1997), and also with other legumes, for
example lupins (Molvig et al ., 1997; Muntz
et al ., 1998; White et al ., 2000; Ravindran et
al ., 2002), oilseeds (Falco et al ., 1995),
cereals (Maruyama et al ., 2001; Lee et al .,
2003; Wu et al ., 2003; Huang et al ., 2005,
2006; Glenn, 2007; Houmard et al ., 2007;
Lucas et al ., 2007; Wakasa et al ., 2007),
potatoes or sweet potatoes (Sevenier et al .,
2002) and forage (Avraham et al ., 2005).
For example, lysine maize ( Zea mays ;
LY038) was developed to accumulate free
lysine (Newell-McGloughlin, 2008) in the
germ portion of maize grain (see Table 7.4)
and to provide an alternative to a direct
supplementation of lysine or to the feeding
of lysine-rich feeds in non-ruminant
nutrition. GM maize LY038  MON810 was
produced from two GM strains by con-
ventional breeding of LY038 with MON810,
which provided the maize plant with
protection against feeding damage from the
European corn borer. Both maize varieties
contained signii cantly more lysine than the
control maize (Table 7.4). h e crude protein
content, and also most of the other essential
amino acids, were increased in GM maize.
Lucas et al . (2007) fed the GM maize (59.2%
in starter and 66.1% in grower/i nisher
diets) to broilers and compared those
maize varieties with unsupplemented and
l-lysine-supplemented diets. Broiler per-
formance and carcass data demonstrated
that the bioei cacy of the incremental
lysine in GM maize was not dif erent from
that of lysine in conventional maize diets
supplemented with l-lysine HCl (see Table
10.12). h is type of technology of free
amino acids was also used for increased
lysine content in canola and soybean and
produced a signii cant increase in
tryptophan levels in grain (Hirschi, 2009).
Apart from higher protein or amino acid
concentration, there are also activities to
develop transgenic crops producing seed
storage proteins with bioactive peptides
(Maruyama et al ., 2011).

7.2 Protein and Amino Acids

Essential amino acids such as lysine,
methionine, threonine and tryptophane
(see Table 7.1) play an important role in the
protein metabolism of humans and animals
(Wu et al ., 2010; see nutrient requirements
of food-producing animals, e.g. NRC, 1994,
1998, 2001; GfE, 1999, 2001, 2008).
Normally, such amino acids lacking in
non-ruminant feeding are supplemented by
adequate crystalline amino acids (Nelson et
al ., 1986; Kidd et al ., 1998; Heger et al .,
2002, 2003; Susenbeth, 2006); so-called
rumen-protected amino acids are used in
ruminant nutrition (Bertrand et al ., 1998;
Robinson, 2010; Robinson et al ., 2010; Chen
et al ., 2011).
Nowadays, new technologies such as
genetic engineering allow improvement of
the protein composition of plants (Galili,
2002; Christou and Twyman, 2004; Galili et
al ., 2005; Beauregard and Hef ord, 2006;
Ufaz and Galili, 2008; Maruyama et al ., 2011;
see Chapter 12). Under such conditions,
there is no longer a need for separate amino
acid supplementation as the lower amounts
now provided by the GM plant are sui cient
to meet the requirements of animals.
Such studies have been done with typical