Exam 1: Genetics Flashcards
Heritability estimates are used to
Evaluate the strength of inheritance for each trait
the percent variation in performance due to genetic effects
Heritability
are reproductive traits maternal or terminal
maternal
reproductive traits heritability and environmental impact
low heritability
big environmental impact
terminal traits heritability
moderate to high heritability
highly heritable trait ex: backfat depth
Why are genetic abnormalities seen so often in pigs
large litters are born at a time and often= more chances for abnormalities
abnormalities
deviations from normal development
can involve any part of the pig
-can impair pigs ability to function or even cause death
-internal or external
anatomical abnormalities or defect occur in at least _____% of newborn pigs
1%
Not all abnormalities are of genetic origin. What are some other possible causes of abnormalities
environmental (viral infection, nutrition, certain drugs)
simple recessive
Two copies of a gene are required for the trait to be expressed
-homozygous dd
-dd affected
-Dd carriers
**most common in pigs
ex: stress syndrome
simple dominant
only one copy of the gene is required to produce the defect
- D_
-weeds itself out
ex: Napole
sex-link recessive
found only on the X chromosome since Y has few active genes
tend to be recessive but MALES will exhibit more often than females
ex: colorblindness in humans
sex-limited
occurs only in one sex because it is related to sexual difference
-recessive or dominant
ex: cryptorchid or scrotal hernia
syndactyly
presence of only 1 toe per foot rather than 2
inherited as a single dominant gene
nearly eliminated from U.S population
“mulefoot”
polydactyly
presence of extra toes and/or dewclaws
fairly common in swine
little economic value (doesn’t affect market, not good for show)
splayleg
most common leg disorders seen in young pigs
rear legs are most often affected but can be forelegs
caused by incomplete development of muscle fibers in the front and rear legs
genetic OR environment (viral, slippery floor, nutrition)
umbilical hernia
“belly rupture” /”belly bust”
Individuals may die during growth due to strangulation of the intestines but most reach market
genetics OR environment (naval infection/staph)
***environment is more common reason
male or female
scrotal hernia
sex-limited condition in males (2 pairs of recessive genes)
Weakness in muscles surrounding the inguinal canal occurs, allowing intestines to drop into the scrotum
usually not fatal
**can be influenced by maternal or environemt
**CANNOT CASTRATE; sent as it to packing plant
nipple abnormalities (2)
inverted nipples
blind nipples
inverted nipples
teat canal is held inward forming a small crater so normal milk flow is prevented
-failure of the nipple to protrude from udder surface
“pin” nipples
always genetic
blind nipples
no visible nipple/canal
caused by environment (injury, irritation, scabbing due to rough floors)
hermaphrodites
have both female and male sex organs (genetic or environment)
normally genetically female but have a portion of male sex organ
may have: tipped vulva or vestigial sheath
how do hermaphrodites occur
large litters due to uterine crowding (share common blood supply due to placenta joining)
cryptorchidism
sex-limited inheritance with at least two gene pairs contributing to the defect
one or both testicles retained in the boars body cavity
if both testicles in a cryptorchid are retained, the boar is ______
sterile
atresia ani
rare
pig born without rectal opening
boars= fatal
gilts= semi fatal
females with no anal opening can defecate through _________ and grow normal
vulva
if prevelence of atresia ani is high, you should cull what
sire
dam
littermates
affected individual
Rendement Napole causes pork to have
low pH
paler color
lower water holding capacity
greater cooking loss
what breed is Napole normally seen in
hampshire
hampshire crosses
is Napole dominant
yes, complete dominant (RN-)
single locus with 2 possible allels: (RN- or rn+)
the dominant allele in Napole is responsible for
Elevated glycogen stores in the muscle that results in increased production of lactate
reduced pH in muscle
Porcine stress syndrome (PSS)
also called malignant hyperthermia, transport myopathy, halothane gene
triggered by stress or excitement
simple recessive inheritance
primary pietrain/ pietrain crosses
not always fatal
signs of porcine stress syndrome
tremors of tail/back/leg
muscle rigidity
inability to walk
respiratory distress because body temp increase
heart failure
PSS is caused by/ what goes wrong to cause PSS
a defect in gate of calcium releasing channel
-prevents the channel from closing
-calcium continues to leak into muscle
-causes a high rate of metabolism to prolong acidosis and fatal collapse
PSS leads to the production of
PSE
(pale, soft, exudative meat)
how to treat PSS
DNA test
homozygous carriers and heterozygous should be culled
examples of maternal traits
number born alive
sow longevity
embryo survival
ovulation rate
examples of terminal traits
meat quality
backfat depth
average daily gain
flavor
hermaphrodites are common in which breeds
landrace and Yorkshire
