Unit 2: Flashcards
Ag
Differential reproduction?
-Preventing some animals from reproducing while allowing other animals to become parents of multiple offspring
-Process of retaining animals that show superiority for the traits we desire and then reproducing the superior individuals
Heritability?
- proportion of phenotypic variation due to genetic variation
Reproductive- lowly heritable
Growth- moderately heritable
Carcass- highly heritable
How is selection response determined?
Selection response is dictated by heritability levels. (higher level= greater response)
Genotype + Phenotype?
Environment?
Genotype:
- result of both cumulative effects of an animal’s individual genes for the trait and the effect of the gene combinations of the parents (can’t be altered or changed)
- Simplified- The Pedigree
Phenotype:
- Observation or measurement of each trait
- Simplified: external appearance (what the animal looks like)
Environment:
- Effects of the summation of all non genetic influences on phenotype
ex. feed, water, shelter
What 2 things make up a phenotype?
- genotype + environment
- Genotype and environment must be maximized in order to maximize phenotype
What is selection differential/reach?
Reach: the superiority (or inferiority) of the selected animals compared to the herd average (distance from mean)
Available selection tools? (4)
- Advanced live evaluation
- Artificial insemination
- Embryo transfer
- Expected progeny difference
What are EPD’S?
- predictor of genetic merit of an individual’s progeny. Difference in performance expected from a sire compared to expected from breed average.
ACC?
accuracy- reliability that can be put on an EDP
Selection Index?
- Recognizes the value of multiple traits and places an economic weighing on the traits of importance
$B, APL, BML, $CHB, SPI, MLI, TSI
Breeding stock selection criteria (regardless of goals)?
Breeding stock selection criteria (regardless of goals)
- Health
- Fertility= libido and semen quality in males, regular estrous cycles in females
-Reproductive traits= Underline, vulva, udder, scrotal, size
-Structural correctness= FEET
- Mothering ability
- Docility
- pedigree/ancestory
- Age @ puberty
Dairy Selection?
Linear classification-
Phenotypic measurements
Looking at biological extremes
A score of 1-50, 25 is the most ideal
Linear classification of Dairy Cattle:
Forms:
Linear classification of Dairy Cattle:
15 traits broken down into 5 categories
1. Form
2. Rump
3. Legs and feet
4. Udder
5. Teats
Forms:
Statue=height
Strength=width
Body depth=capacity
Dairy form=angularity
Swine breeding selection? 4 main criteria
Structural soundness
Volume and performance
Balance and design
Reproductive qualities
Selection for reproductive traits:
Low in heritability
Improved by cross breeding
Highly important on economic scale
Perhaps the largest determinant in profit and loss
Measurable reproductive traits:
Number born alive
Number weaned
21-day litter weight
Wean to estrus
Conception rate
Number of parties
Number of functional nipples
Pigs per sow per year
Growth traits:
Moderate in heritability
Traits relate to performance and efficiency
Huge impact on feed conversion
60-70% of all prod. costs are in feed
Measurable growth traits:
Days to market
Average daily gain from weaning to the point of time
Weight per day of age from when they were born to present time
Days to 250 lbs
Feed efficiency aka fuel economy
For every $100 in prod. Costs, 60-70% will be in feed
Carcass traits:
High in heritability
Important because fatter hogs are less efficient
Consumers conscious of their fat intake
pros/cons
What packing industry pays for has reflected consumer demand
Measurable carcass traits:
10th rib fat- indicator of total carcass fat
Loin eye area- total carcass muscle
Carcass length- as length increases, fat decreases and vice versa
Color, firmness, and marbling scores- indicated muscle quality
STAGES?
What traits does STAGES measure?
Swine testing and genetic evaluation system
Developed by purdue university
Use expected progeny differences to measure economically important traits
Traits measured by stages-
Number born alive(+)
Days to 250 lbs (-)
Pounds of lean(+)
Back fat (-)
Sow productivity index(+)
Maternal line index(+)
Terminal sire index (+)
Sow productivity index:
Maternal line index:
Terminal Sire Index:
Measures animal’s ability to pass on maternal traits
Index accounts for numbers born alive, 21-day litter weight, and contemporary group average.
Measures ability to pass on maternal and terminal EPD’s
Index includes number born alive, 21-day litter wight, days to 250, and back fat
Terminal sire index-
Index includes traits that are important for market hog production
Traits included in TSI are days to 250, back fat, LEA and pds. Of lean
Beef Evaluation:
Ideal breeding female- soundness, fleshing ease, performance, bodily condition, balance
Soundness:
Skeleton: correctness
Joints: angles, flexibility
Movement: foot placement, length of stride
Performance-
The ideal breeding heifer
Frame score round 6
Hip height relative to age
weight
60% mature weight at 1 year of age
fertile
Individual performance:
Individual performance:
Birth weight (60-80lbs)
Weaning weight (100lbs per month of age. 4 month=400 lbs)
Yearling weight (100 lbs per month of age)
Average daily gain (end weight-starting weight/days)
Weight per day of age (end weight-birth weight/days)
