The activities of these commercial breeding
companies are characterized by the following
features:
Pedigree selection occurs in the nucleus
only.
• Selection is strictly within specialized lines
(or breeds). These lines are designated as
sire and dam lines and are selected with
different intensities. In poultry bred for
meat and in pigs, male lines are selected for
growth and lean meat production, while
female lines are selected for reproduction.
New lines are constantly developed either
by crossing between existing lines or by
further selection in a given direction.
• The final product is a cross between two or
more pure-bred lines.
For economic reasons, each breeding company
will sell under several trademarks (accumulated
through acquisitions and fusions), but will in fact
only have a limited number of differentiated
products. Indeed, pig or poultry breeding
companies develop lines to meet few (two or three) breeding goals, which vary depending
on the extent of their global market share
and the degree of variation in the production
environments in which the clients operate. For
example, a breeder may develop a high-yielding,
fast-growing line for use under high-input
conditions where superior-quality feed allows the
expression of the animals’ full genetic potential,
and a line for more challenging environments
that is more “robust”, but has lower performance
for production traits.
The activities of these commercial breedingcompanies are characterized by the followingfeatures:Pedigree selection occurs in the nucleusonly.• Selection is strictly within specialized lines(or breeds). These lines are designated assire and dam lines and are selected withdifferent intensities. In poultry bred formeat and in pigs, male lines are selected forgrowth and lean meat production, whilefemale lines are selected for reproduction.New lines are constantly developed eitherby crossing between existing lines or byfurther selection in a given direction.• The final product is a cross between two ormore pure-bred lines.For economic reasons, each breeding companywill sell under several trademarks (accumulatedthrough acquisitions and fusions), but will in factonly have a limited number of differentiatedproducts. Indeed, pig or poultry breedingcompanies develop lines to meet few (two or three) breeding goals, which vary dependingon the extent of their global market shareand the degree of variation in the productionenvironments in which the clients operate. Forexample, a breeder may develop a high-yielding,fast-growing line for use under high-inputconditions where superior-quality feed allows theexpression of the animals’ full genetic potential,and a line for more challenging environmentsthat is more “robust”, but has lower performancefor production traits.
การแปล กรุณารอสักครู่..
