Animal Science Exam 2 - [10/16/12]

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What is a breed?

Animals of common origin having characteristics that distinguish them from other groups of the same species
Most breeds develop to fit a set of environmental constraints and/or production desires
What are the two new breeds (hybrids)? Define both.
Composite breeds: 2 or more breeds combined with known percentages to form a new breed (ex. Brangus)

Synthetic Breeds- 2 or more breeds combined with estimated percentages to form a new breed (Gertrudis)
Hereford cattle come horned and polled which is genetically the same, but polled is a ___________ gene?
Where were cattle first domesticated?
Europe and Asia
What are the primary bloodlines of cattle?

Bos Taurus
Bos Indicus
Bos Bisea
Describe the Bos Taurus breed.

British breed.
appear in more temperate zones
include Bos Primigenius & Bos langifrons

Decribe the Bos Indicus breed

"zebu" cattle of Asia, India, and Africa
humpbacked with droopy ears
disease & parasite resistant and heat tolerant
Primary animal used in crossbreeding for Southern U.S. and South America

Decribe the Bos Indicus breed

"zebu" cattle of Asia, India, and Africa
humpbacked with droopy ears
disease & parasite resistant and heat tolerant
Primary animal used in crossbreeding for Southern U.S. and South America

Decribe the Bos Indicus breed

"zebu" cattle of Asia, India, and Africa
humpbacked with droopy ears
disease & parasite resistant and heat tolerant
Primary animal used in crossbreeding for Southern U.S. and South America
Classification of breeds fall into three categories: Sire breeds, Maternal breeds, and Dual purpose breeds. Describe the purpose of each,

Sire breeds tends to belarger-framed, heavier muscled and faster growing
Maternal breeds are known for their milking ability and mothering ability. They tend to be smaller framed and light muscle but higher in carcass quality
Dual purpose breeds are breeds that fall between sire and mothering breeds

Name the Classification Groups in order.
Name the Order, Family, Genus, Species of cattle.
Artiodactylai (even toed/hoofed)
Bovidae (hollow horn)
Bos (hollow horn(
Bos Taurus/Bos Indicas
What is the ability of offspring to out perform the ability of the parent breeds?
Heterosis/Hybrid Vigor

What is the purpose of Breed complementarity.complimentary of traits?
They take advantake of the parents more disirable traits

What is the best breed/cross breed?

Ther eis no best breed or cross breed.
What are the two types of Cow-Calf production?

Commercial (grocery store production)
Purebred (produces replacement genetics)
What does a Stocker Operator do?
Takes weaned calves and grazes them on cheap grains
What is the purpose of a seedstock producer?

Provides replacement genetics such as bulls, heifers, and semen/embryos
How much is earned in Commercial feedlot production?
15 to 20k, and as much as 100k to 250k
How much is earned in Farmer/Feeder feedlot production?
3 to 5k, as much as 10-15k
Elaborate on Texas and beef cattle production.

First place in beef cow production with 5 million head, making up 10% of the U.S. Production
Also First in cattle on feed with 2.33 million head making up 18% of production

How can you determine age by teeth?
calf and yearling- temporary incisors
2 yr : central pair of 4 permanent incisors
3 yr: 4 permanent incisors
4 yr: 6 permanent incisors
5 yr: 8 permanent incisors
6 yr old: partial wear
7-10 years: wear from center incisors outward
12 yrs: teeth triangular/stubs
What is the purpose of identification of beef cattle?
To establish ownership
Individual identification
Age identification
Disease contro programs
What are the 5 purposes of dehorning cattle?
Reduction in shed/feed space
To eliminate bruising
Value to packer
Ease of working
What are the four different ways to dehorn?
Dehorning cattle
Dehorning cup
Hot iron

What is the purpose of castrating bull calves?
A more docile temperament
Lean meat texture/marbling
They fatten fatter
Can be allowed to mix with heifers
Prevents the reproduction of inferior genetics
Name the four methods of castration, and which two are bloodless?
Knife (most common)
burdizzo (bloodless)
elastrator (bloodless)
When evaluating beef cattle, what visual aspects should you inspect?
Size and scale
Structural correctness
sex character
Why should you be concerned with structural correctness?

-It influences longevity
-Influences ability of bulls to breed and for cows to harvest forage
*cattle selected for increased fram size must have corresponding decline in correctness of the skeleton

What is the acceptable REA bH for muscle?
11 and 15 square inches
What is the fleshing ability?
the ability of a cow to regain condition after calving
What 3 things (the 3 "uts") determine a good or bad keeper?
Body Capacity

--lots of muscle = good
--Roomy gut = good (flat sided butts/guts are bad)
Testicles (Nuts lol)
--total sperm output increases
--% abnormalities decrease
--daughters reach puberty earlier
What parts of the mammary system are evaluated?

Teat size and shape
Udder depth
Udder balance
Udder quality
What are the four parts of the Performance Evaluation?
Performance testing (thru gain test or ultrasound data)

What two things are evauated in the Contemporary Group?
Conception rate & Calf crop weaned (%)

What two things are evaluated in Maternal Performance?
Weaning weight & cow efficiency
What 3 things are considered in weaning weight adjustments?

-Weaning age of calf
-Age of dam
-Sex of calf
What is the weaning weight?
205 days!

Cow efficiency tends to favor _______ cows?

What three things influence growth performance?
--Yearling Weight
--Average daily weight
--Feed efficiency
Four Genetic Eval terms.

-Expected progeny differnce (EPD)
-Accuracy (ACC)
-Maternal milk (EPD)
-Yearling weight (EPD)
Name the signs of Estrus.

-Stands to be mounted
-Mucus secretion
Growth promoting substances are either natural or a copy of a natural compound. What percentage of cattle are given these substances? What percentage of carcass weight is increased weight per unit of feed?
63% of all cattle are given the enhancers, 90% of all fed cattle are given these enhancers. 8-12% increase in carcass weight is found;
Name three growth enhancers.
--methane inhibitors
Sire selection will account for ___ to_____% of the improvements to the herd.
85 to 95%
Name a few beef cattle diseases.
internal parstes- worms
external parasites- ticks, fleas, flies
foot rot
Johne's disease (paratuberculosis)
grass tetany
bovine viral disease

At what age do bulls and heifers reach puberty?
10 months

How long is the estrous cycle?
21 days
What is the length of Estrus?
18 hours

What is the time of ovulation?
12 hours post-estrus
How long is the gestation period in cows?
283 days

Is later better than earlier for artificial insemination?

What are hormones?
used to improve feed ifficiency and average daily gain. This method has been used and research since 1952.
What is the largest money generating commodity in all of agriculture in recent times? It accounts for _____% of the money made for all the agricultural branches combined.
The Beef Industry
Accounts for 40% money made for all agricultural branches combined.
What is the gross annumal income of the beef industry in the U.S.?
35 billion dollars
What does inbreeding do to the number of recessive genes in the population of a herd?
It allows them to be expressed
Phenotypic Effects of Inbreeding --->
-Increased phenotypic uniformity if accompanied by selection
-superior genetics: high % of homozygous chromosomes which means they are likely to pass on
-Results in animals that are less vigorous and proves detrimental to preweaning

How is inbreeding used in livestock production?
Crossing of inbred lines (heterosis) quickly identifies undesirable recessive genes/traits. Some develop superior breeding values (uniform progeny)
-Sire and daughter mating to reveal undesirable genes
There are four types of Outbreeding.

1. Outcrossing (unrelated animals w/in same breed)
2. Species crossing (different species)
3. Cross breeding (different breeds)
4. Grading up (purebred sire+grade females and their offspring)
What it hybrid vigor defined as?
the superiority of the crossbred offspring over the average of the pure breeds (parents) used to make the cross
The top two primary reasons to cross-breed are

hybrid vigor/heterosis
complementarity of traits

What is the preferred system of mating for commercial swine production?And is also used extensively in the sheep industry?
The two basic types of crossbreeding in cattle include:

Rotational: Combining 2 or more breeds
Terminal- does not keep replacements--all animals go to market
The genetic effects of crossbreeding, the opposite of inbreeding, results in...
increased hybrid vigor
How is outcrossing used in a herd?

The most popular system, unrelated animals within the same breed are mated to form mostly heterozygous pairs

"Grading up," only useful in cattle and horses is.....................
the continuous use of purebred sires of the same breed

What does the future hold for livestock mating systems?

Composite animals: that fit their environment, are super efficient, and super productive
Increased testing: performance and genetic

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