Breeding Programs for Dairy Cattle
5 Principles of Good Genetics
1. Animal Identification permanent
2. Performance Evaluation production, type (purebred)
3. I.D. the superior genotype (PTAs)
4. Make widespread use of superior genotype (A.I. bulls from 80t
Cryptorchidism: in males - failure of the testis to descend into the scrotum. Usually testes
descend into the scrotum shortly before birth.
Estrous cycle: female the cycle of hormones that prepares the cow for pregnancy
Foods of animal origin contribute significantly to the nutrients in the average U.S. diet
63% of the Protein (19% Dairy)
23% of the Energy (8.6% Dairy
99% of the Vitamin B12 (20% Dairy)
However, they also contributed:
95% of the cholestero
Milk Composition Products
Whole Milk: 3.25% Fat and 8.25% SNF
2% Reduced-Fat milk: not less than
1% Low Fat Milk
Skim Milk (fat free): less than 0.5% fat
and at least 8.25% SNF
o Vitamin A
o Vitamin D
1. Name the major arteries supplying each half of the udder and the major veins draining each half of the udder.
The external pudenal artery supplies each half of the udder with blood.
The external pudenal vein and the subcutaneous abd
Evaluating the Cattle
What do we want to evaluate?
1. Type conformation, physical appearance
associated with performance
associated with longevity
Type evaluation is subjectively measured
o need a trained evaluator
o more variable, les
Evaluating and Grading Milk
Why is milk so regulated?
1. It is highly perishable
2. Easily subject to adulteration
Quality what does this imply?
Cleanliness and car in production and handling indicated by microbiological count
Possession of desirable ar
The average dairy cow produces 20,500 lbs of milk per year.
Domestication of dairy cattle and the use of milk for human food began somewhere in
Northeast Africa or Asia 6000-8000 BC
Why was domestication of animals importa
There are 7 breeds of Dairy Cattle
Breed: a group of animals related by descent, possessing common characteristics
(traits) and developed for a particular function
Registered (Purebred): animals whose parentage (dam & sire) o
Dairy Cattle Genetics
Genetics & Breeding
Choosing the parent of the next generation
Natural survival of the fittest
Artificial we make decisions
o Selection of the sire & dam
o Cow culling voluntary or involuntary (not as goo