Traits, Phenotypes, and Genotypes

ANSC 401 - Exam 1

how do we characterize animals?

in terms of appearance or performance, or both

trait

any observable or measurable characteristic of an animal

how do we characterize animals?

in terms of appearance or performance, or both

trait

any observable or measurable characteristic of an animal

observed trait

describes the appearance of an animal

measurable trait

can be subjectively measured and reported

examples of observed traits

• coat color

• size

• muscling

• leg set

examples of measurable traits

• weaning weight

• speed

• staple length

phenotype

an observed category or measured level of performance for a trait in an individual

genotype

the genetic makeup of an animal — provides genetic background for phenotype

environmental effects

the external factors (nongenetic) that alter an animal’s phenotype

biological type

a classification for animals with similar genotypes for traits of interest

animals with similar genotypes are said to be of the same _______ ______

biological type

how can the question, “What is the best animal?” be answered?

it can be answered by knowing what traits are of primary importance and what genotypes and phenotypes are most desirable for those traits

system

a group of interdependent component parts

what are the parts of a system?

• animals (genotype)

• physical environment

• fixed resources and management

• economics

define the animal category of the system

contains the characteristic genotype(s)

define the physical environment of a system

contains those elements to which humans have very little control, such as the weather, soil type, and altitude

define the fixed resources in a system

include items like size of the farm, opportunity to grow supplemental feeds and available labor

define the management part of the system

involves the policies of the farmer such as amount of feed, health care, and culling rate

define the economics part of the system

refers to the cost for farm inputs (feed, labor, supplies) and the prices of farm outputs (sales of animals)

what’s an interaction?

a dependent relationship among components of a system in which the effect of any one component depends on other components present in the system

what must be understood to determine the best genotype?

must have knowledge of the environmental, managerial, and economical components and how they interact with genotype to affect profitability

describe genotype by environment interactions

dependent relationships between genotypes and environments in which the difference in performance between two (or more) genotypes changes from environment to environment

breed

races of animals within a species and different breeds are often genetically adapted to different environments

breeding objective

a general goal for a breeding program — a personal idea of what constitutes the best animal

commercial producer

an animal breeder whose primary product is a commodity for public consumption

purebred

a group of animals wholly of one breed or one line

line

a group of related animals within a breed

seedstock

animals whose role is to be a parent or, in other words, contribute genes to the next generation — traditionally purebred, but don’t have to be

intermediate optimum

an intermediate level of performance that is optimal in terms of profitability and/or function

what is the purpose of animal breeding?

to make the next generation better

How does Dr. Jay Lush define breed?

“A breed is a group of domestic animals, termed such by common consent of the breeders, ...a term which arose among breeders of livestock, created one might say, for their own use, and no one is warranted in assigning to this word of a scientific definition and in calling the breeders wrong when they deviate from the formulated definition. It is their word and the breeders common usage is what we must accept as the correct definition."