July 11, 2008

Animal Breeding Glossary

Albino: Animal with no skin or eye pigments.
Albinism: Allele that produces albinos.
Allele: Any one of the alternative forms of a gene occupying the same locus on a chromosome.
Assortive mating: Mating animals that look alike.
Artificial insemination (AI): Technique of collecting semen from a male and inserting it into the vagina of the female.
Autosomes: Ordinary chromosomes of the animal as opposed to the sex chromosomes.
Back-cross: Cross between a first cross (F1) and either of its parents.
Blood lines: General term used to describe relationships.
Breeding Value (BV): Assessment of the future genetic potential of an animal.
Carrier -
Chromosome: Thread-like structure in the cell nucleus that carries the genes.
Cleft palate: Defect where the palate is divided causing young animals difficulty in sucking.
Common ancestor: Ancestor that appears on both sides (sire’s and dam’s) of the pedigree and links both sides.
Corrective mating: Mating parents with different traits to obtain a balance in their offsping.
Correlations: Statistical term to describe the relationship or association between traits.
Crossbred: Progeny from crossing two breeds, lines or strains.
Culling: Removing poor animals from a flock, herd or population.
Dissasortive mating: Mating animals that are not alike to balance up traits.
DNA: Deoxyribonucleic acid which is the chemical compound that makes up the basic structure of the genes.
Diploid: The normal double chromosome state in the cell which has the correct number of chromosomes for the species.
Distribution: Statistical term to describe the variation or spread in a series of observations on animals.
Dominant: Condition where one allele masks the effect of the other (recessive) allele.
Embryo transfer (ET): Technique where after fertilisation the embryo is transferred from one female to another.
F1: First filial (daughter) generation or the first cross.
F2, F3 etc: The subsequent filial generations or crosses.
Gamete: Reproductive cells (male sperm and female eggs) that unite to produce the offspring or zygote.
Generation interval: Average age of the parents when the offspring are born.
Genes: Basic units of inheritance.
Genome: The total number of genes that make up an organism.
Genotype: Genetic makeup of the animal.
Germplasm: Genetic material of the animal.
Half bred: F1 or first cross.
Haploid: Half the genetic makeup of the animal, found in sperm and eggs. After fertilisation the normal diploid is restored.
Heritability: Strength of inheritance of a trait.
Heterosis: Genetic state when animals of different genetic makeup (genotypes) are crossed. When compared to the mean of both parents, it can be positive or negative.
Heterozygote: Organism that received unlike alleles for a specific gene from its parents.
Homozygote: Organism that received like alleles for a given gene from its parents.
Inbreeding: Mating animals that are related and have common ancestors.
Inbreeding coefficient: Rate at which homozygosity is increased (and heterozygosity decreased) in a population.
Inbreeding depression: Lowered performance that arises through increased inbreeding levels.
Index: Prediction or estimate of an animal’s genetic potential for a range of different traits.
Lethal gene: Gene which when expressed can cause the death of the animal.
Locus: Point a gene occupies on a chromosome. Plural is loci.
Mean: Average of a range of values.
Meiosis: Cell division in reproductive (germ) cells where the chromosomes are reduced from the double (diploid) state to the half (haploid) state.
Mitosis: Cell division of body cells where the new daughter cells receive the normal diploid set of chromosomes.
MOET: Multiple ovulation followed by embryo transfer.
Mongrel: Crossbred that is not viewed with favour.
Multiple ovulation (MO): Where the ovary of the animal is stimulated by hormones to produce more ova (eggs).
Mutation: Change in the genetic material (germplasm) of the animal.
Normal distribution: Bell-shaped distribution that shows variation in a trait or a population. Also called the Gausian curve after the mathematician who developed it.
Nucleus: Central part of the cell where the genetic material (chromosomes and genes) are found.
Ovum transfer: Technique of removing ova from one female and inserting them in another.
Phenotype: Outward expression of an animal’s genetic makeup or genotype.
Prepotent: Animal that regularly passes on its traits to it’s offspring.
Population: Group of animals or collection of data.
Population genetics: Study of the inheritance of traits controlled by many genes.
Recessive: Allele that is masked by another dominant allele.
Reciprocal cross: Crossbreeding where the previous parent breed or strains are reversed from male A x female B to vice versa.
Reduction division: Stage in cell division when the chromosome number is halved.
Relative economic value (REV): Estimate of the relative value (in dollar terms) of a number of different traits so they can be added together.
Repeatability: Statistical term used to describe the chance of traits being repeated over an animal’s lifetime.
Selection differential: Difference between the mean of the chosen parents for the next generation, and the mean of the population from which they came.
Selection index: Value that sums up the future breeding potential of an animal. An estimate of how good the animal will be as a parent.
Sex chromosome: Chromosome concerned with the inheritance of sex of the animal.
Sex linked: Traits carried on the sex chromosomes.
Sibling (sib): Offspring of the same parents, but not necessarily born at the same time. Full sibs have both parents in common and half sibs share one parent.
Stud: Term to describe animals that are registered with a breed association.
Top cross: Cross by a sire from a new blood line of the same breed.
Trait: Character or characteristic on the animal that breeders want to change.
Variation: Measure of differences you see in a range of animals.



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