Agriculture Reference
In-Depth Information
last 30 years these purebred strains have been selected only for appearance. Therefore, at the
moment, no optimum breed for organic agriculture seems to be available. The production rate
of purebreds is too low, and modern hybrids have a tendency for feather pecking and cannibal-
ism. In the long run, the development of a dual-purpose breed (meat and eggs) could be the
solution for organic farming. Both meat and egg performance will be lower than of modern
hybrid strains, however. Therefore, consumers must be convinced to buy these more expensive
products. Prices for organic eggs or meat are relatively high. Furthermore, the efforts of organic
farmers or associations will be necessary. The big breeding companies will not develop an
organic breed in the short term because the organic market is too small for them.
Genotype × environment interactions (G × E) pose an additional challenge to using per-
formance information. Generally, G × E interactions mean that animals of the same origin
might give different performances in different environments. The G × E interactions are more
important in very different environments; therefore, the performance of animals in vastly dif-
ferent environments can be difficult to compare. For example, Sorensen (2001) has shown that
a purebred laying hen (Danish Skalborg) had a similar performance in both cage and alterna-
tive housing systems. However, the compared hybrids had a lower production in alternative
than in cage systems. Similarly, a local breed (Sonali) showed a better performance than
Lohmann Brown hens under semi-scavenging conditions in Bangladesh (Sorensen 2001). Up
to now, no information is available for G × E interactions that compare conventional and
organic agriculture (Boelling
et
al
. 2003). One important precondition to estimating G × E
interactions is that a great deal of data is necessary.
Another problem is that testing facilities normally work conventionally at least with pigs or
poultry. For example, in intensive feeding and housing systems, only concentrates are used,
which is not allowed in organic agriculture. In addition, results obtained under such condi-
tions might not be transferable to organic conditions.
Breeding practices
According to IFOAM standards and EU regulations, breeding practices should respect the
animals' natural behaviour. Therefore, natural mating is preferred. Methods that depend on
complex technologies should be avoided. Embryo transfer and cloning are prohibited.
Hormones to induce ovulation and birth are prohibited unless for medical reasons, although
AI is permitted.
Invasive techniques like AI or embryo transfer do not respect the natural behaviour of an
animal species, and farmers may become more dependent on breeding companies. Further-
more, the genetic basis of a breed will be reduced with these techniques because fewer breeding
animals are used. Organic livestock husbandry aims for natural breeding methods. However,
AI is still common with some species. In Germany for example, most organic dairy farmers are
still using AI,whereas beef farmers mainly use natural mating (Hörning
et
al
. 2004b).
Embryo transfer (ET) is prohibited in organic farming. However breeding bulls used for AI
are often produced via ET. Furthermore, criteria should be set up for bulls for natural mating
in many countries. Other options to encourage the use of natural mating are rotation of
breeding animals with other farms, or some farmers could be paid for keeping male breeding
animals. Natural breeding normally results in a higher breeding success because the sire is
better able to detect oestrous females. However, if the sire inherits health problems that only
become apparent later on, many descendants will be affected.
Another question is whether quantitative trait loci (QTL) methods should be used in
organic agriculture (Pryce
et
al
. 2004). In identifying the genes responsible for certain breeding
traits, gains can be increased. These molecular techniques are becoming increasingly common
in conventional breeding; for example, testing for the malignant hyperthermia syndrome
