Dairy Selection

Question 1

Traits of Importance

Answer 1

Milk Production
Fertility
% Fat
Type
Temperament
Calving ease

Question 2

Milk Production

Answer 2

h2 = 0.35
* Milk yield - 305 days after calving
* Type traits - weak positive correlation
* Fat yield - high positive correlation
* % fat = negative correlation

Question 3

Fertility traits

Answer 3

Heifer pregnancy
First service conception
Days open
Rebreeding rate
Stayability

Question 4

Type traits

Answer 4

Stature
Strength
Body depth
Dairy form
Rump angle and width
Edder clept
Frontal teat placement
Teat length
Feet and leg composition

Question 5

Crossbreeding

Answer 5

Not much
Some interest to improve reproduction, but main objective is milk production

Question 6

Source of genetic improvement in dairy

Answer 6

Mainly based on sire (due to quicker progeny production)

Question 7

National Dairy Herd Improvement Association

Answer 7

DHIA
System of records of performance to account for sources of variation

Question 8

Ultimate success of dairy industry

Answer 8

Utilization of record system based on comparisons of contemporaries on a similar bases
(Limited number of traits selected)

Question 9

bST (Bovine Somatotropin)

Answer 9

Naturally occurring hormone in cows that is the major regulator of milk production

Question 10

Genomics

Answer 10

The large scale use of DNA information to estimate the genetic merit of cattle

Genetic maps of what traits animal inherited from each of its parents is available and summarized into genomic evaluations

Question 11

SNP

Answer 11

single nucleotide polymorphism

Question 12

Genetic Disease

Answer 12

disease that can be passed from generation to generation

Question 13

Cervical Vertebral Malfunction

Answer 13

Caused by a missense mutation in the bovine SLC35A3

Question 14

Bovine Brachyspina Syndrome

Answer 14

Monogenic Autosomal recessive hereditary disorder
Main phenotype seen is shortening of spine
Caused by 3.3 kb deletion in chromosome 21

Question 15

Bovine Leukocyte Adhesion Deficiency (BLAD)

Answer 15

Autosomal recessive disorder
Phenotype - recurring infection of soft tissue, fever, low appetite, chronic pneumonia, and diarrhea
Single point mutation at position 383 of CD18 gene

Question 16

Syndactyly (Mule Foot)

Answer 16

Autosomal recessive with variable penetrance
Phenotype - Animals have fusion of two digits causing animals to have only one claw on at least one foot (Front feet most commonly affected)
[Carriers associated with super milk and fat]

Two indep. mutation in the bovine LRP4 gene

Question 17

Bovine Progressive Degenerative Myeloencephalopathy (Weaver)

Answer 17

In Brown Swiss breed
Autosomal recessive disorder
Phenotype - Animal shows bilateral hind leg weakness between 6-18 months, resulting in weaving gate
Caused by BTA 4: 46-56 mb missing bases