Dairy Selection Flashcards
What traits are of importance for dairy selection?
milk production
Does dairy selection involve crossbreeding?
no, very little
Why would crossbreeding be used in diary selection?
improve fertility/reproduction
What are examples of single purpose dairy breeds?
Holstein, Jersey, Brown Swiss, Aryshire, Milking Shorthorn, Guernsey
What are Holsteins leaders in?
number 1 breed when it comes to milk yield
What are Jersey good for?
percent fat in milk
What are the ways milk yield in cows is measured?
- 305 milk yield
- total fat yield
- % protein
- %fat
If the 305 milk is high…
the total fat is high
What correlation do % fat and milk production have?
-0.40
What protein does milk contain?
casein
What are fertility traits?
- calving interval
- days open
- first service conception
- calving ease
What are examples of type traits?
- stature
- chest width
- angularity
- rump angle
- rear leg set
- foot angle
- front/rear teat placement
- udder depth
- central ligament
What heritability does milk production have (number)?
0.35
What correlation do fat yield and milk production have?
+ 0.75
What correlation does type and milk production have?
weak, positive
What correlation does reproduction and milk production have?
probably negative
What happens to milk production after calving?
milk production occurs and then decreases over the lactation period
What is the first objective of crossbreeding?
milk production
What breed is superior for milk production?
holstein
What breed is superior for % milk fat?
Jersey
What should days open not go beyond?
90 days
What does SCS stand for?
somatic cell score
What is somatic cell score used to measure?
mastitis
What are the sources of genetic improvement in dairy?
- sires of sires
- dams of sires
- sires of dams
Most of the genetic progress by selecting is based on ____.
sires
Very little genetic progress by selecting is based on ______.
dams (dams of dams)
Why is selection based primarily on sires?
they can transmit genes much faster than females
Why are sires so important when all important traits are sex-limited?
- number of progeny vs dams
- AI allows for even larger number of progeny (45% of operations have no bulls)
- selection based on close female relatives and progeny testing of offspring
What is the dairy record system called?
National Dairy Herd Improvement Association (DHIA)
How are records listed in the DHIA?
Modified Contemporary Comparison
What is Modified Contemporary Comparison?
standardization of all records of performance to account for as many sources of variation in performance as possible
What is DHIA operated through?
NCSU
How are sires selected?
based on PTA
what does PTA stand for?
predicted transmitting ability
What is PTA?
predicting performance of an animal in comparison to the average
How does a person determine which sire to select?
choose the sire that is high in a trait you are deficient in
Do you want the sire to be closely or distantly related?
despite the high amount of inbreeding in the dairy industry, you want a sire that is distantly related
What has lead to the ultimate success of the dairy industry?
- utilization of record system based on comparisons of contemporaries on a similar basis
- limited number of traits selected
- adaption of technology
How has the dairy industry adapted to technology?
- AI
- environmental control to optimize environment to maximize production
What environmental controls are placed in the dairy industry?
- health programs
- nutrition
- facilities
- equipment
What is bST?
a naturally occurring hormone in cows that is a natural regulator of milk production
What is bST used for?
administration of exogenous bST can increase milk production
What is another name for exogenous bST?
Posilac
What happens if a cow treated with Posilac has adequate nutrition?
increase in IGF-I and an increase in milk production
What happens if a cow treated with Posilac has inadequate nutrition?
no change in IGF-I and no change in milk production
Does BST affect milk composition?
no
What is a downside to treating cows with bST?
increase incidences mastitis, but if you adjust for the increased milk production the incidence is not increased
What is genomics?
- the study of the genome of the animal
- the large-scale use of DNA information to estimate the genetic merit of cattle
What knowledge does genomics include?
the knowledge of differences in DNA sequences of individual cattle and associating these differences with actual performance
What is genomics (map)?
genetic map of what traits animal inherited from each of itts parents available and summarized into genomic evaluations
What does genomics include the combination of?
their PA and genotypic data
What are some inherited diseases in dairy cattle?
- Cervical Vertebral Malfunction
- Bovine Brachyspina Syndrome
- Bovine Leukocyte Adhesion Deficiency (BLAD)
- Syndactyly (Mule Foot)
- Weaver
What was Cervical Vertebral Malfunction first discovered in?
Holsteins in Danish, USA, UK, Netherland, and Japanese herds
What was Cervical Vertebral Malfunction traced back to?
a single bull called Carlin-M Ivanhoe Bell
What was Cervical Vertebral Malfunction caused by?
a single missense mutation in the bovine SLC35A3
What was Bovine Brachyspina Syndrome traced back to?
Sweet Haven Tradition
What is Bovine Brachyspina Syndrome?
shortening of the spine, growth retardation, reduced body weight, uneven teeth alignment, and malformation of internal organs
What was BLAD traced back to?
Osborndale Ivanhoe, the common bull used in the 50s/60s
What type of disease is BLAD?
autosomal recessive
What is BLAD?
recurring infection of soft tissues, fever, low appetite, chronic pneumonia and diarrhea, severe ulcers, stunted growth, and impaired wound healing
What was Mule Foot traced back to?
a single ancestor in Holstein
What type of disease is Mule Foot?
autosomal recessive with variable penetrance
What is Mule Foot?
fusing of the two digits causing the animal to have only one claw on at least one foot (front feet are most commonly affected)
What are carriers of Mule Foot associated with?
superior milk and fat
What was Weaver traced back to?
Brown Swiss, arose from inbreeding
What type of disease is Weaver?
autosomal recessive
What is Weaver?
animal shows bilateral hind legs weaknesses between ages 6-18 months resulting in a weaving gate. Abnormal reflexes and function in the hind legs
What is environmental control?
creating a type of microclimate that is different than climate that prevails in that area
How are embryo calves raised and where does the egg come from?
egg comes from a superior female fertilized by a superior male, and are raised by less superior female
What does bST stand for?
Bovine Somatotopy
What is IGF-I?
insulin-like growth factor 1 (a growth hormone)
Does Posilac cause mastitis?
no, the increased milk production does
How many base pairs is a kilobase made of?
1,000
How many base pairs is a mega base made of?
1,000,000
What could a single base difference result in? and what is this referred to as?
a superior animal; SNP
What are SNPs?
single nucleotide polymorphism
What does GEBV stand for?
Genomic Estimated Breeding Values
What does NM$ mean?
net merit
What does PL stand for?
productive life
What is a missense mutaiton?
single base change (point mutartion)
Why do people still breed mule foot?
not every offspring will have this trait, carriers also produce better milk
What does BTA stand for from BTA 4?
Bostaurus autosome
What base change will not lead to a different protein being made?
synonymous
What base change will lead to a different protein being made?
non-synonymous
What kind of disease is Bovine Brachyspina Syndrome?
monogenic autosomal recessive hereditary disorder
What is Bovine Brachyspina Syndrome caused by?
a 3.3 kb deletion in the bovine Fanconi anemia completion group 1 (FANCI) gene on CHROMOSOME 21
What caused BLAD?
a single point mutaiton (adenine to guanine) at position 382 of the CD18 gene which caused an aspartic acid to glycine substitution at amino acid 128 in the adhesion molecule CD18
What causes Syndactyly?
two independent mutations in the bovine LRP4 gene
What is Weaver mapped to?
BTA 4 (chromosome 4): 46-56 mb
What is SNPs associated with?
genes expressed in the nervous tissue
