animal science chp. 28
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Are most market breeds purebreds or crossbreds?
CROSSBREDS
Seedstock providers still use what kind of swine? and what are they?
purebreds • Yorkshire • Duroc • Berkshire
Seedstock providers may also still use what kind which were crossbreds and then selected via a specialized selection program?
Hybrids
Know the pig breeds (maternal & paternal)
pictures
What is symbol for swine?
set of tragets for measurable traits that form the ideal market hog
Symbol I for what
market barrows
Symbol II is for what
market gilts
Symbol III is for what
market goals adopted in 2005
Sow productivity is extremely high in what kind of importance?
its high in economic importance
How is sow productivity measured?
litter size number weaned per litter 21-d litter weight number of litters per sow per year
What combo is important for sow productivity and what must be managed to have low heritability?
combo of # of pigs born alive and litter weight at 21 days is important environment must be managed to have low heritability
Growth rate is economically important and has a heritability of what?
35%
What is feed efficiency?
pounds of feed required per pound of gain
Feed efficiency has a heritability of what percent and how expensive is feed?
heritability of 30% and feed is expensive bc it is 60-70% of production costs.
When measuring feed efficiency feed intake must be measured, how can this be done?
• at boar-testing stations • can select for correlated traits such as gain and backfat
By finding the carcass traits of swine, what are we trying to figure out? and what percent of heritability does carcass traits have?
estimate the pounds or percentage of acceptable-quality lean pork in the carcass 48%
Traits used to predict carcass composition in swine:
• Fat depth over the loin at the 10th rib • Loin muscle area • Carcass muscling score
Is structural soundness heritable? Can it be improved through visuall selection?
unsoundness is moderately heritable yes can be improved with visual selection
Inherited defects like Cryptorchidism-
retention of one or both testicles in abdomen * Hernias * Inverted nipples * PSE (Pale, soft, and exudative) carcasses and porcine stress syndrome (PSS)
How can we improve these traits?
use performance records!
in commercial swine- what genetic do they use?
one source of genetics
STAGES
Swine testing and genetic evaluation system
What does STAGES do?
Computes genetic evaluations for several traits within a single herd (EPDs) Creates bioeconomic indexes: * Sow productivity index (SPI) * Terminal sire index (TSI) * Maternal line index (MLI)
When selecting replacement females of commerical swine, find gilts that are…
fast-growing, sound, moderately lean with good body capacity