AGB 121: Principles of Animal Genetics and Population Genetics (2+1)

Correlation between important economic traits

PHENOTYPIC (r_P), GENETIC (r_A) AND ENVIRONMENTAL CORRELATION (r_E) BETWEEN IMPORTANT ECONOMIC TRAITS IN FARM ANIMALS

Traits	rP	rA	rE
Cattle
Milk yield: Butter fat yield	0.93	0.85	0.96
Milk yield: Butter fat per cent	- 0.26	- 0.38	- 0.18
Pigs
Weight gain: Back fat thickness	0.0	0.13	- 0.18
Growth rate: Feed efficiency	- 0.84	- 0.96	- 0.50
Weight gain: Feed efficiency	0.66	0.69	0.64
Sheep
Fleece weight: Staple length	0.35	0.35	0.40
Fleece weight: Crimps per inch	- 0.21	- 0.56	0.10
Fleece weight: Body weight	0.36	0.11	-
Poultry
Body weight: Egg production	0.01	- 0.17	0.08
Body weight: Egg weight	0.33	0.42	0.23
Egg weight : Egg production	-0.05	-0.31	0.02

• The r_A and r_E are different in magnitude, or even in sign. A difference in sign between the two correlations indicates that the genetic and environmental sources affect the characters through different physiological mechanism.

Correlations	Negative	Positive
Low	- 0.2 to - 0.4	0.2 to 0.4
Medium	- 0.4 to - 0.6	0.4 to 0.6
High	- 0.6 and above	0.6 and above