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Mathematics may hold the answer to how much of a dairy goat's observed
traits are the result of genetics versus environment. Researchers
devised a formula that describes the genetic and environmental components
of conformation traits such as a goat's strength, stature, and udder
shape. The equation even separates temporary environmental factors such
as seasons from permanent ones such as injury. It considers the influence
of all the animal's relatives--not just the sire, as in other models--and
provides insights into heredity's role. Least likely to be influenced by
genetics are rear udder arch and rear legs. But stature, teat diameter and
placement are highly heritable. By accurately estimating the heritability
of valued traits, breeders may be better able to calculate dairy goats'
genetic merit. Researchers developed the formula using data from the
American Dairy Goat Association. Records from 154 herds and six breeds
were used, and pedigrees were included for animals born in 1978 or
later.
Animal Improvement
Programs Laboratory, Beltsville, MD
Suzanne Hubbard/George Wiggans, (301)504-8334
Cattle breeders who screen young bulls for potential natural-mating
fertility by measuring testicle size and semen quality may soon be adding
another criterion--scrotal temperatures. Using an infrared
camera-like device, scientists measured 73 bulls' scrotal surface
temperatures in a pattern from top to bottom of each testis. Surface
temperatures typically were 1.5 to three degrees warmer at the top of the
scrotum than at the bottom. In a 45-day breeding test, a typical
14-month-old bull with a uniform progression of decreasing scrotal surface
temperatures impregnated 15 of 18 heifers. In contrast, bulls that didn't
have this uniform temperature pattern impregnated about 16 percent
fewer.
U.S. Meat Animal Research Center,
Clay Center, NE
Donald D. Lunstra, (402) 762-4188
Last updated: October 22, 1996
Return to: Quarterly Report
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Last Modified: 02/11/2002
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