Module 7

Animal Breeding

is the science that deals with the application of the various animal

genetic principles purposely to improve or enhance the performance of livestock and poultry species.

Animal Breeding

It is an art and science of the genetic improvement of animals.

Genetic improvement

is the purposeful manipulation of the genetic constitution of animals which

determines the expression of their inherent characters.

Genetics

is the science that deals with heredity and variation (those characters that can be due to the characteristics of their parents).

1. Natural

2. Artificial

Mating Scheme type

Inbreeding

– a form of non-random mating of closely related animals by ancestry

Linebreeding

– a form of inbreeding which is done to concentrate the characteristics of a

superior ancestor

Backcross

– a crossbred mated back to one of the two parents

Crossbreeding or outcrossing

– refers to mating between animals of different established breeds;

the genetic effect would be the increase in heterozygosity of genes- improvement of the average performance of the progenies over the parents (hybrid vigor)

hybrid vigor

– average superiority of offspring over the parents

breed complementation

– combining the good characteristics of the breeds

Rotational Cross

-use of two or more breeds in regular sequences (subscripts indicate that there is no backcross)

upgrading

– a mating system where an inferior breed in mated to a superior

breed to improve characteristics of the lesser breed (usually the mating of

exotic breed to a native breed)

Topcrossing

– mating of males and females which are considered top in their performance pedigrees

Selection

– process of choosing animals with desirable traits that are to be maintained and

reproduced in a herd or flock

Individuality

– animal’s own performance record

Pedigree

– records of ancestors

Progeny Test

– on basis of performance of offsprings

Collateral Relatives

– based on performance of relatives (cousins, aunts and uncles)

Tandem

– only on trait at a time is being considered

Independent Culling Level

– 2 or more traits at a time is measured; if one trait did not

pass the standard it will not be selected

Selection Index

Combining all traits included in the selection program into an index; usually gives

best results; each trait is given weight in the selection

Backfat

– amount of distinctive fat in the meat (acceptable value is 2 cm thick)

Average daily gain (ADG)

– daily growth rate

Feed Conversion Efficiency (FCR)

– measures the amount of feed needed to produce a kg gain in weight

total gain in weight/total days of fattening

adg formula

total feed consumed/total gain in weight

fcr formula

Genetic Improvement.

This phenomenon occurs when the genetic merit of the animals improves

through selection.

Selection

. It is the process in which some individuals with desirable traits are chosen over others as parents of the next generation.

Natural Selection.

Selection which occurs in nature independent of deliberate human control.

Artificial Selection

. Selection that is under human control.

Tandem Method

- this is the method of selection which focuses on improving one trait at a time. Thus, improvement requires a longer time span compared with other selection methods.

Independent Culling Level -

method of selection wherein individual animals will be evaluated based

on a set of standard traits. Individuals that fail to reach one of the set standards will be rejected or culled. In this way, selected animals will have no undesirable traits.

Selection Index

- method of selection wherein multiple traits are being considered. Unlike independent culling level, this method gives each trait a merit and the total core for all traits was used in the selection. Animals with the highest merit or selection index can be considered as breeder replacements.

Mating System.

It is the set of rules for mating.

Inbreeding

. It is the mating of animals more closely related to each other than the average

relationship within the population concerned. The relationship includes mating like a parent to offspring, brother to sister

Close inbreeding

- an example of inbreeding where mating between sibs or between parents

and progeny is allowed to achieve a relatively high degree of homogeneity.

Line breeding

- a milder form of close inbreeding wherein relationship of mated individuals is

kept close as possible to some ancestors.

inbreeding depression

One disadvantage of inbreeding is the ______ is the opposite of hybrid vigor which results in a decrease in the performance of inbred commonly observed in traits such as fertility and survivability (these traits are also known for having very low heritability estimates). Shown below is the inbreeding coefficient between mates.

Outbreeding

. Is the opposite of inbreeding wherein mating of animals that are less closely related to each other than the average of the population is allowed.

Outcrossing

- the mating of two animals within a pure well-defined breed. If two lines

within the same breed are separated for about 4 to 5 generations and the sire is used in another herd then that accounts for outcrossing.

Top crossing

- the mating of highly inbred sires (best sire in the pedigree) to the dams of

the base population of the non-inbred population.

Upgrading or grading up

- mating which allows the repeated use of pure breed sire over

females of non-descript population.

Cross breeding

- the mating of two individuals from different distinct breeds.

Hybrid

by definition means an individual that is a result of combination of species, breeds within a species, or lines within a breed.

Crossbreeding

is the act of mating sires of one breed or breed combination to dams of another

breed or breed combination thereby resulting in crossbred.

Complementarity

. The improvement in the overall performance of offspring resulting from the mating of individuals with different but complementary breeding values.