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ANS 422: Beef Systems and Management > Genetics > Flashcards

Genetics Flashcards

1
Q

What is a breed?

A

A stock of animals or plants within a species that have gone through intensive, deliberate selection and breeding to result in a distinctive appearance and set of traits that are passed uniformly to the offspring.

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2
Q

Which 4 categories of traits should producers focus on?

A
  1. Current herd performance.
  2. Economically relevant traits.
  3. Production system and feed resource based traits.
  4. Traits favored in the current market.
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3
Q

What are some economically relevant traits?

A
  1. Weight at sale.
  2. lbs. of retail weight.
  3. Tenderness.
  4. Feed efficiency.
  5. Docility.
  6. Likelihood of calving ease.
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4
Q

What are growth traits based on?

A
  1. Age of the dam (older=heavier).
  2. Genetics of the sire and dam.
  3. Maternal environment.
  4. Milk traits of dam (what the calf consumes and uses to grow exclusively early on).
  5. Nutrition (energy and protein).
  6. Weather (colder=bigger calves).
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5
Q

What are the markers used to measure growth traits?

A
  1. Yearling weight.
  2. Mature height.
  3. Mature weight.
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6
Q

What is weaning weight based on?

A
  1. Age of dam.
  2. Age at weaning (older=heavier).
  3. Dam’s milk.
  4. Genetics of sire and dam.
  5. Sex (male=heavier).
  6. Quantity and quality of forages.
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7
Q

What is yearling weight based on?

A
  1. Weaning weight.
  2. Nutrition post-weaning.
  3. Sex.
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8
Q

What reproductive traits are selected for?

A
  1. Calving difficulty.
  2. Fertility.
  3. Scrotal Circumference.
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9
Q

What carcass traits are selected for?

A
  1. Carcass weight.
  2. Fat thickness.
  3. Marbling.
  4. Ribeye area
  5. Yield Grade.
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10
Q

What are other traits that are generally selected for?

A
  1. Soundness.
  2. Temperament.
  3. Feed efficiency.
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11
Q

How many breeds of beef cattle exists worldwide? In the U.S. ? Make a significant contribution to the total number in the U.S. ?

A
  3. 10-15.
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12
Q

What are the 3 general breed categories?

A
  1. Bos indicus.
  2. British.
  3. Continental.
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13
Q

What classifies cattle as Bos indicus?

A

They must be fully or a high enough of a percentage Bos indicus to show traits.

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14
Q

What are the 2 alternate names for the Bos indicus breed?

A
  1. American.
  2. Synthetic.
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15
Q

What is the Bos indicus breed known for?

A
  1. Disease resistance.
  2. Heat tolerance.
  3. Pest resistance.
  4. Tougher meat.
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16
Q

Where are British breeds originally from?

A

The British Isles.

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17
Q

What is the alternate name for British breeds?

A

English breeds.

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18
Q

What are the characteristics of British breeds?

A
  1. Generally smaller.
  2. Increased fleshing.
  3. Increased marbling.
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19
Q

Where are Continental breeds originally from?

A

Mainland Europe.

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20
Q

What is the alternate name for the continental breed?

A

Exotics.

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21
Q

What are the characteristics of Continental breeds?

A
  1. Cutability.
  2. Generally larger.
  3. Generally lean.
  4. Generally muscular.
  5. Weight gain.
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22
Q

What colors are Brahman cattle?

A
  1. Light Gray.
  2. Red.
  3. Almost black.
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23
Q

What were the Brahman cattle developed from?

A

Various imports of Gir, Guzerat, and Nellore from India in 1849.

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24
Q

What are the colors of Beefmaster cattle?

A

Various colors.

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25
Are Beefmaster cattle horned or polled?
Can be either.
26
What cattle were Beefmaster cattle developed from?
Brahman (~1/2), Hereford (~1/4), and Shorthorn (~1/4) Cattle.
27
What are Beefmaster cattle selected based on?
1. Conformation. 2. Disposition. 3. Fertility. 4. Hardiness. 5. Milking ability. 6. Weight.
28
What color are Brangus cattle?
Black.
29
Are Brangus cattle horned or polled?
Polled.
30
What two cattle breeds are crossbred to create Brangus cattle?
Brahman (3/8) and Angus (5/8).
31
What color are Santa Gertrudis cattle?
Deep, cherry red.
32
Are Santa Gertrudis cattle horned or polled?
Can be either or can be scurred.
33
What are scurs?
Small pseudo-horns that are attached to the flesh, but not the skull.
34
What are 6 other Bos Indicus breeds?
1. Barzona. 2. Braford. 3. Bahmousin. 4. Braler. 5. Gelbray. 6. Simbrah.
35
What breed has the most registrations annually?
Black Angus.
36
What color are Black Angus?
Black.
37
Are Black Angus horned or polled?
Polled.
38
What traits is the Black Angus breed known for?
1. Calving ease. 2. Meat quality.
39
Where does the Black Angus originate?
Aberdeenshire and Angushire of Scotland before arriving in the U.S. in 1873.
40
What color is the Red Angus breed?
Red.
41
Is the Red Angus breed horned or polled?
Polled.
42
Why was the Red Angus breed founded?
As a performance breed.
43
What color are Hereford cattle?
Red body with a white face, brisket, and abdomen.
44
What is the subset of Hereford cattle?
Polled Hereford, created from naturally polled Hereford found amongst horned ones.
45
What color are Shorthorn cattle?
Red, White, or Roan.
46
Are Shorthorn cattle horned or polled?
Either.
47
What are 8 other British breeds of cattle?
1. Belted Galloway. 2. Galloway. 3. Lincoln Red. 4. Red Poll. 5. Scotch Highland. 6. South Devon. 7. Welsh Black. 8. White Park.
48
What is the color of Charolais cattle?
White.
49
What are the characteristics of Charolais cattle?
1. Heavy muscled. 2. Horned or polled.
50
What color are Simmental cattle?
Yellow to red and white color pattern or black.
51
Are Simmental cattle horned or polled?
Either.
52
What were Simmental cattle initially selected for?
Dual purpose for meat and milk.
53
What color are Limousin cattle?
Golden red to black.
54
What characteristics do Limousin cattle have?
1. Heavy muscled. 2. Polled or horned.
55
What color are Gelbvieh cattle?
Golden to red or black.
56
Are Gelbvieh cattle horned or polled?
Either.
57
What is unique about how the Gelbvieh breed was introduced to the U.S. ?
It was done through semen importation.
58
What are the 9 other continental breeds?
1. Braunveih. 2. Chianina. 3. Maine-Anjou. 4. Marchigiana. 5. Piedmontese. 6. Pinzgauer. 7. Romagnola. 8. Salers. 9. Tarentaise.
59
What are the other breeds of cattle?
1. Beefalo. 2. Chiangus. 3. Corriente. 4. Longhorn. 5. Watusi.
60
What is the Germ Plasma Evaluation Program?
A program used for breed characterization on a set list of traits.
61
What 9 traits are examined in the Germ Plasma Evaluation Program?
1. Calving ease. 2. Carcass composition. 3. Cow size. 4. Efficiency of growth. 5. Herd life. 6. Maternal performance. 7. Meat quality. 8. Rate of growth. 9. Reproduction.
62
What are the breed comparisons based on?
Averages.
63
What are performance records?
Records of how the individual performed for a given trait.
64
What factors are used to evaluate the usefulness of a performance record?
1. Ability to compare differences. 2. Adjusted for environmental effects. 3. Contemporary group to minimize environmental effects and estimate genetic differences. 4. Objective, accurate, honest measurements.
65
Where are performance records measured?
On farm or at a central testing facility.
66
What is conducted at testing centers that contributes to performance records?
1. Bull tests. 2. Feedlot/carcass evaluation programs. 3. Heifer development programs.
67
What is required for good record keeping?
1. Accuracy. 2. Multiple categories ( Carcass, disposition, growth, maternal ability, reproductive growth). 3. Adjusted for known environmental effects and management practices.
68
What are the 3 purposes of a bull test?
1. Provide breeders with sound scientific basis for selecting bulls with ability to gain weight rapidly and to make them available to cattlemen. 2. Record differences in ability of bulls to gain in uniform environment. 3. Serve as an educational demonstration of the value of records of performance. *Aid in marketing breeding stock.
69
What is the purpose of a heifer development program?
To develop heifers for replacement breeding stock.
70
What are the steps of a heifer development program?
1. Heifers are consigned to a central location. 2. Fed for an ADG of 1.5-1.75 lbs. 3. Disposition, frame score, pelvic area, reproductive tract score, and structure. 4. Bred by artificial insemination. 5. Return home or sold.
71
What 2 things does a heifer development program allow for?
1. Uniform development of heifers. 2. Marketing options.
72
What is the purpose of a feedlot/carcass performance evaluation program?
Allow producers to obtain feedlot and carcass performance date. *Allow smaller producers to retain ownership.
73
What are the steps of a feedlot/carcass evaluation program?
1. Producers consign cattle. 2. Cattle are fed at a central feedlot. 3. Carcass data is collected. 4. Producers are paid on a USDA Yield and Quality Grade basis with expenses deducted from animal value.
74
What is the general rule when it come to breeding commercial cattle? Why?
a. Commercial cattle producers should crossbred. b. Breed complementary and heterosis.
75
How does a high heritability impact breed complementary?
It results in high breed complementary.
76
How does a high heritability impact heterosis?
It results in low heterosis.
77
Where are females in a 2 Breed Rotational mating system?
They stay in their original group.
78
What is the genetics of the replacements heifers from group 1 in a 2 Breed Rotational mating system?
50% Group 1 Dam/50% Group 1 Sire.
79
What is the genetics of the replacements heifers from group 2 in a 2 Breed Rotational mating system?
50% Group 2 Sire/25% Group 1 Sire/25% Group 1 Dam.
80
How many females are necessary for a 2 Breed Rotational mating system to be cost effective?
60 females, 30 per bull. *Heterosis not maximized.
81
What is the genetics of the replacements heifers from group 3 in a 3 Breed Rotational mating system?
82
How many females are necessary for a 3 Breed Rotational mating system to be cost effective?
90 females, 30 per bull.
83
What is the difference between a terminal sire cross and a 3 Breed Rotational mating system?
The replacement females from Group 3 do not enter group 1.
84
What is a rota-terminal cross?
Younger replacement females are moved between Group 1 and 2. Older replacement females are moved to a terminal sire.
85
How many females are needed for a rota-terminal cross?
Less than 60.
86
How often are sires rotated in a rota-terminal cross?
Every 3 years at minimum.
87
What are 2 other systems of crossbreeding?
1. F1 bulls. 2. Composites.
88
What are F1 bulls?
Bulls that are crossbred that are used to introduce new genetics into herds.
89
What is the composites system?
Raising crossbred animals as purebred animals.
90
What happens to heterosis as the amount of breed relatedness increases?
Heterosis decreases.
91
What questions are important to ask during crossbreeding?
1. Most appropriate grazing system and any issues w/ grazing that may limit mating system alternatives? 2. What is the cost and labor availability? 3. How much complexity can be effectively managed? 4. How important is simplicity and convenience to implementing the breeding program? 5. Cost and availability of desired breeds? 6. Cost effectiveness and feasibility of AI? 7. Marketing plan?
92
What are the 4 reasons crossbreeding fails to achieve its desired results?
1. Breeds with too much growth, milk, birth weight, or mature size are overused. 2. Mating system is too complex or is not implemented in a systematic manner. 3. Poor quality bulls are used. 4. Seedstock producers fail to develop expertise and service orientation to assist clients in development of effective crossbreeding systems.
93
What is selection?
The practice of determining which individuals will become parents. *Change is inevitable, progress is optional.
94
What are the 2 types of selections?
1. Artificial selection. 2. Natural selection.
95
What do selection goals serve as?
1. Clear picture of desired genetic change. 2. Guides to day-to-day selection decisions. 3. Initial step in genetic improvement. 4. Preventing progress from becoming arbitrary changes in selection overtime.
96
What is tandem selection?
Selecting one trait at a time and getting them to a desired level before selecting for a second trait. *Least effective selection method.
97
What is independent cull level?
Minimum culling levels for each trait are set. *Most common type of selection used.
98
What is the major disadvantage with independent culling levels?
If an animal is slightly below the minimum for one trait but highly superior in other traits are still culled.
99
What is the selection index?
Where economic values are placed on each trait. *Difficult to construct.
100
What does a good selection index use?
Statistical methods.
101
What does using statistical methods to build a selection index allow for the inclusion of?
1. Economic value. 2. Genetic correlations. 3. Heritability. 4. Variability for multiple traits.
102
What is the pedigree selection method used for?
1. When progeny information is not available. 2. Traits expressed later in life. 3. Sex-limited traits.
103
How commonly is individual appearance/performance used?
Widely used.
104
What type of traits is individual appearance/performance best applied to?
Highly heritable traits.
105
What does individual appearance/performance analysis permit?
Rapid generation turnover and shorter generation interval.
106
What is progeny testing used for?
Low heritability traits.
107
What are the 3 disadvantages of progeny testing?
1. Longer generation interval. 2. Only a limited number of animals can be progeny tested. 3. Poorly conducted tests can yield misleading results.
108
What does expected progeny difference allow for?
Comparison of animals across herds or even breeds.
109
What are pedigree estimate EPDs?
EPDs estimated based off the pedigree.
110
What is marker-assisted selection?
Selection for specific alleles using genetic markers.
111
What are 3 commercially available gene markers that are used in marker-assisted selection?
1. Black coat color. 2. Polled. 3. Various genetic disorders.
112
What are Genomic Enhanced EPDs (GE-EPDs)?
An EPD that combines progeny data, pedigree, performance, and genomic test results.
113
What are across-breed EPD adjustments most useful for?
Purchasing bulls for use in crossbreeding programs in commercial settings.
114
What do across breed EPD adjustments emphasize?
1. Divergence for terminal crossbreeding. 2. Divergence of birth weight EPDs for bulls to breed to first calf heifers. 3. Uniformity for rotational crossbreeding.
115
What does the across-breed EPD depend upon?
The accuracy of within-breed EPD for the bull. *EPD for most recent sire summaries only.
116
What are breeds moving to for incorporation of genomic information?
Single-step procedures.

ANS 422: Beef Systems and Management (8 decks)

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