Tip of The Day - October 5, 2016

Photo by Tom Semadeni

First snow

1987 Selection in a Closed Swine Herd

Gail Belonsky and Brian Kennedy did this study. Gail was a student from Cornell University who did her Master's with Brian. She later became employed in the stock markets in New York city.

Computer simulation of a closed 100 sow and 4 boar swine herd was used to study different selection methods on genetic change, inbreeding, and genetic variance over a ten year period for traits with heritabilities of .10, .30, and .60. Selection of replacement animals was based on either individual phenotypic performance or estimated breeding values from a BLUP animal model. Culling was either at random on age and reproductive performance or on the basis of individual phenotypes or BLUP EBVs.

Genetic gain was greater with BLUP selection than with phenotypic selection, but relative differences narrowed with increasing heritability. The proportional effect of culling on genetic gain was relatively independent of heritability and type of selection, but there was a tendency for culling on BLUP evaluations to be more effective at low heritability.

Inbreeding was higher with BLUP selection. As heritability increased, inbreeding increased with individual selection, but tended to decline with BLUP selection. Genetic variance was reduced most with BLUP selection, but rate of response was still greater than with individual selection because of greater accuracy of evaluation.

Photo by Tom Semadeni

Northern highway