ANSC 1000 Name________________________________
Exam 2
Fill in the blank with the best word or phrase. All numbers must have units.
DO NOT USE INITIALS.
_________________________1. A term that refers to the time when the
reproductive organs become functionally operative.
_________________________2. The amount of time between the birth of a calf and
the birth of a subsequent calf, both from the same
cow.
_________________________3. The phenotype of an individual is the result of two
interacting "forces." For most traits, which one of
these two most affects (influences) the phenotype?
What do the following two terms mean? (2 pts each)
4. Parity
5. Full sibs
Be careful! Don't spend too much time on these problems and end up not having enough
time to finish the exam.
6. (4 pts) You select replacement gilts having a backfat thickness of 1.3 inches
from your herd which has an average backfat thickness of 1.6 inches. The gilts
are bred to a boar with 0.9 inches of backfat that was selected from this same
herd. What is the expected backfat thickness of the offspring from this mating?
(h2 = 0.4)
7. (4 pts) A farmer has a herd of pigs whose average postweaning gain is
1.80 lb/day. The farmer selects breeding animals (gilts and boars) from
this herd that average 2.30 lb/day. If the offspring of the selected
animals gain 1.95 lb/day, what was the heritability of postweaning gain?
Computer graded. Use a soft-leaded pencil. One answer per question.
1. Steers grazing cool-season pastures in Alabama would gain ? lb/day.
A. 6-8 B. 0.8-1.2 C. 1.3-2.0 D. 2.5-3.0 E. 3.0-3.5
2. Pigs weigh ? pounds at birth.
A. 1.5-2.6 B. 2.7-3.3 C. 5-7 D. 9-12 E. 14-17
3. Lamb carcasses weigh ? percent of the live weight.
A. 40-42 B. 50-52 C. 60-62 D. 70-72 E. 80-82
4. The percent lamb crop in a farm flock operation is
A. 90-92 B. 120-130 C. 140-150 D. 160-180
5. Calves put directly in the feedlot after weaning will be about ? months old
when ready for slaughter.
A. 7-9 B. 9-12 C. 12-15 D. 15-18 E. 18-21
Questions 6 through 12. Match the following terms with the definitions given below.
A term may be used more than once.
A. heritability B. accuracy of selection C. selection differential
D. selection intensity E. generation interval
6. How well we can predict the genotype of an individual from his phenotype.
7. Refers to the proportion of individuals from a herd that will be selected for
the next generation.
8. The proportion of the differences among animals in a herd for a particular
trait that is transmitted to the offspring.
9. Inversely affects the rate of genetic progress; that is, the greater this is
the slower genetic progress will be.
10. A measure of the superiority of the selected animals compared to the herd from
which they came.
11. The fraction of the total phenotypic variation that is due to genetic make-up.
12. Prolificness has a major impact on the numerical value assigned to this term.
13. Generation interval is best defined as
A. the average age of the offspring when they start to reproduce.
B. the average length of time from the birth of one offspring to the birth of
the next.
C. the average number of years (difference in ages) between the grandparents,
the parents and the offspring.
D. the average age of the parents when the offspring are born.
Questions 14-15-16. Consider the following three traits:
(An answer may be used more than once.)
A. loin eye area B. litter size C. days to 230 lb.
14. Which trait could you make the most genetic progress through selection?
15. Which trait would you make the least genetic progress through selection?
16. Which trait would have the greatest amount of heterosis through crossbreeding?
17. Why would you want to adjust the weaning weight of calves?
A. To make your herd look better than it really is.
B. To make your herd more uniform.
C. To decrease variation.
D. To increase the accuracy of selection.
E. Both B and C.
18. In which of the following traits would genes account for the highest portion
of the differences among animals?
A. litter size B. frame size C. loin eye area D. weaning weight
E. feed efficiency
Questions 19 through 26. Select the best answer from the list below.
A. Appearance B. Pedigree C. Performance test
D. Progeny test E. Records of relatives
19. The most accurate method of identifying superior breeding stock.
20. Using the records of ancestors to select replacement animals.
21. Best method of detecting soundness problems.
22. The state bull test conducted at Auburn University represents this method.
23. Use this method to select replacement gilts that will increase the average
loin eye area in a herd.
24. The problem with this method is the amount of time it takes to get reliable
information about the individual.
25. Evaluate an animal on the basis of his own records.
26. Which two of these methods are often used in the selection of young dairy
bulls?
A. b and d B. c and d C. b and c
D. a and c E. a and d
27. The pedigree method is an excellent way to identify superior breeding stock
if an ancestor won or placed high in a major livestock show.
A. true B. false
28. We performance test bulls, boars and rams
A. to determine their actual genotypes
B. to minimize the effects of environment on their phenotype
C. so we can find out which ones have the best libido.
D. to promote the best breeds.
E. All of the above.
29. You have a young bull weighing 1600 lb. who will ultimately weigh 2200 lb.
when he is mature. If he breeds some cows now, would you expect the
offspring to be smaller at maturity than the offspring he would sire after
reaching his 2200 pound mature weight?
A. yes B. no
30. In which class of farm animals can you make the most rapid progress through
selection?
A. hogs B. dairy cattle C. beef cattle D. sheep E. horses
31. Animals in breed A have a 500-lb. weaning weight, and those in breed B have
a 580-lb. weaning weight. The breeds are used in a crossbreeding program
and the calves weigh 600 lb. at weaning. We would say the cross resulted
in heterosis.
A. true B. false
32. Suppose the calves in the previous question weighed 560 lb. at weaning. We
would say the cross resulted in heterosis.
A. true B. false
Questions 33 through 41. Use the following answers.
A. Linebreeding B. Inbreeding C. Outcrossing D. Crossbreeding
33. Results in the most homozygosity
34. Results in the most heterozygosity
35. Used to "fix" certain traits so they will breed true.
36. Used to concentrate the inheritance of an ancestor in the pedigree.
37. The most widely used system in range flock operations.
38. The most widely used system in commercial swine operations.
39. Used to take advantage of breed complementarity.
40. The black baldy results from this.
41. You have a purebred herd, and there is no inbreeding. Which system
is being used?
42. Inbreeding can be expected to
A. decrease reproductive performance.
B. decrease postweaning growth.
C. make animals susceptible to environmental stress.
D. All of the above are correct.
E. Only A and B are correct.
43. Crossing inbred lines usually results in
A. heterosis
B. increased death rate
C. decreased performance
D. genetic abnormalities
E. Only B and C are correct.
Questions 44 through 50. Mark A = true or B = false.
44. When selection intensity is high, the selection differential will be
greater than when selection intensity is low.
45. Selection intensity almost always is greater for males than for females.
46. The selection differential for any one trait will be greater when we
select for several traits simultaneously than when selecting for only that
one trait.
47. If we standardize the environment, it becomes relatively easy to determine
the genotype for many of the economically important traits.
48. Sometimes, selection for one trait will cause us to "lose ground" in another.
49. Inbreeding is almost never done in the cattle, sheep, swine, and horse
industries.
50. Grading up can lead to a commercial herd having genetic composition
approximating the level of purebreds.
51. A cryptorchid bull
A. produces sperm but no testosterone.
B. produces both sperm and testosterone.
C. produces testosterone but no sperm
D. produces neither sperm nor testosterone.
52. The mating of the male and female animal is called
A. conception B. fertilization C. zygote D. copulation
E. either A or B
53. Scrotal circumference in a young bull is an indication of
A. libido B. semen volume C. sperm production
D. presence of normal sperm
Questions 54 through 67. Find the correct answer from the lists below
and mark the corresponding letter on your answer sheet. Answers may be
used more than once.
A. Leydig cells A. prostate gland A. urethra
B. seminiferous tubules B. bulbourethral gland B. FSH
C. sertoli cells C. vas deferens C. LH
D. rete testis D. seminal vesicles D. Testosterone
E. epididymis E. sigmoid flexure E. GnRH
Sperm production is a complicated process. The hypothalamus of the brain
releases a hormone called _#54_ which goes to the pituitary and stimulates the
release of two hormones. One of these hormones, _#55_, stimulates the _#56_
cells in the testes to produce testosterone. The testosterone, in turn,
stimulates the _#57_ in the testes to produce sperm. At the same time, the
second hormone released by the pituitary, _#58_, stimulates the _#59_ in the
testes to produce nutrients for the sperm. The sperm are then transported
from inside the testes to the _#60_ where they mature and are stored until
ejaculated. During mating, the sperm are transported from the testes via
the _#61_ and are dumped into the _#62_ of the penis. The accessory sex glands
also add volume to the semen. The _#63_ supply nutrients for the ejaculated
sperm and in some species, the _#64_ produces a gelatinous material which forms
a cervical plug. The hormone that is necessary for sperm survival in the testes
is _#65_. The hormone that is responsible for the growth and development of
the accessory sex organs is _#66_. The hormone responsible for the secondary
sex characteristics of the male is _#67_.
68. The hormones known as gonadotropins are
A. FSH and LH.
B. GnRH, LH and FSH
C. testosterone, LH, FSH.
D. GnRH and testosterone
E. testosterone, LH, FSH, GnRH
69. Which males deposit semen into the cervix rather than the vagina?
A. bull and ram B. bull and boar C. boar and stallion
D. ram and boar E. ram and stallion
70. The sperm gets its energy from the
A. head B. neck C. midpiece D. tail
71. The acrosome is located where on the sperm?
A. head B. neck C. midpiece D. tail
72. The male animal having the least semen volume is the
A. stallion B. bull C. boar D. ram
73. The farm animal having the most prominent uterine horns is the
A. sow B. beef cow C. mare D. ewe E. dairy cow
74. The site of fetal attachment is the
A. cervix B. vagina C. oviduct D. uterus
75. The site of fertilization is the
A. ovary
B. uterus
C. upper (anterior) third of the oviduct
D. lower (posterior) third of the oviduct
E. cervix
76. A female has all the oogonia at birth that she will ever have.
A. true B. false
77. Sperm get from the site of deposition to the site of fertilization mainly
by the whipping action of their tails.
A. true B. false
78. Sperm can get from the site of deposition to the site of fertilization in
approximately five minutes.
A. true B. false
79. All of the events that occur from one period of heat to the next in a
female is called
A. estrus
B. estrus cycle
C. estrous period
D. estrous
E. estrous cycle
80. Referring to the previous question, the length of time in a ewe from one
heat period to the next is about
A. 16-20 hours B. 5 days C. 17 days D. 21 days E. 365 days
81. Development of an oogonia into a follicle is stimulated by
A. GnRH B. LH C. FSH D. estrogen E. both LH and FSH
82. The ? catches the ovum at the time of ovulation.
A. oviduct B. infundibulum C. corpus luteum D. mesentary
E. ovundibulum
83. Estrogen is produced by the
A. anterior pituitary B. antrum C. posterior pituitary
D. corpus luteum E. hypothalamus
For questions 84 through 90. Use the following answers.
A. LH B. FSH C. GnRH D. estrogen E. progesterone
84. The excitatory hormone in the female.
85. Causes ovulation to occur.
86. Necessary to maintain pregnancy.
87. Stimulates the development of the corpus luteum.
88. Stimulates development of the secretory glands in the mammary tissue.
89. Keeps the female reproductive tract in a quiescent state.
90. Responsible for the secondary sex characteristics of the female.
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