ANSC 4406 Sheep and Goat Production Exam 2

TTU ANSC 4406 Sheep and Goat Production Exam 2

What sheep have a long breeding season?

Fine wools

Hair Sheep

Romanov

Finn Sheep

Dorset

What sheep breeds are medium length breeders (when day length shortens in the fall)?

Black face breeds

Columbia

Corriedale

What 3 breeds are short season breeders (later in fall and seasonal breeders)?

Long wool

Cheviot

Shropshire

When do ewes reach puberty?

5 - 12 months depending on season

Name the length of a ewes estrous cycle, length of estrous, and gestation

Estrous cycle: 17 days/Range 14 - 20

Estrus: 20 - 42 hours/Avg. 30 hours

Gestation: 143 - 152 days/5 months

Why would a producer choose to use a "once per year" lambing scheme?

Conventional

Lamb when you want them to

Easiest and simplest

Uniform Age Group

Least Number of Lambs

Why would a producer choose to use a "continuous" lambing scheme?

Maximum Number of Lambs

Never take bucks out

Lambs born year round

Low management

What are the disadvantages of a "twice per year" lambing scheme?

Early post-partum infertility

More labor intensive

Why are hormones used in lamb operations?

A) Use to synchronize sheep

B) Increase ovulation rate and cause multiple births

C) Induce puberty

D) Cause cycling during anestrus period

E) All of the above

What is the importance of progesterone in lambing operations?

Progesterone is used to synchronize estrus

Name the different ways administer progesterone

Inject: labor intensive have to do once or twice a day for 12-14 days

Pessary: sponge with progesterone; goes in vagina and goes through walls. Can lose and get infected

MGA: melengesterol acetate= feed for 12-15 days then stop

Remove 12-15 days after then ewe will ovulate in 2-4 days; better on second ovulation

Best way to synchronize ewes and why must you?

use of a CIDR and females must be induced into estrus

What is the importance of estrogen in a lambing operation?

Produced by follicles

Grow = Increase

Jump start system faster

Highest just before and during estrus

Prepares uterus for pregnancy

Try to stimulate ovulation

What are the two gonadotropins used to induce ovulation?

A) PMSG

B) Estrogen

C) HCG

D) Progesterone

E) None of the above

You plan to AI all your ewes in two months. You remove a CIDR in the ewes after 15 days and check heats with a teaser ram. After removing the CIDR, what injection will you give to induce ovulation in the ewes?

A) PMSG

B) Estrogen

C) Antibiotic

D) Progesterone

E) None of the above

What are the 4 main ways to care for a ram?

Keep ram cool

Observe breeding activity

Have 1 ram per 25-50 ewes

Stagger breeding if breeding to many ewes

What are ways to check pregnancy on sheep?

Marking Harness: cheap and accurate; start with light crayon; change every 17 days

Checking Udders: 3 months bred

X-Ray

Ultrasound: expensive; 35 days; good operator tells multiples

Rectal abdominal palpation: 60-70 days

What factors should be considered when breeding a ewe?

Season: fertility increases in October than June

Light: decrease day length

Temperature: rams can become sterile in heat

Breed

Puberty: at 5-12 months

Age: peak reproduction at 3, 4, and 5 years

Body Weight: a 10 lb increase in body weight = 6% ovulation rate increase

Presence of Ram

Nutrition

Disease

What factors should be considered when breeding a ram?

Season: introduce when ewes are fertile

Light: decrease day length

Temperature: testicle temp is 4 - 10 F below body temp

Breed

Puberty: at 4 - 5 months

Social Dominance

Age:1 year old is most fertile but 1 - 5 years old is good production

Nutrition

Fertility: 1 mL should contain 8 billion sperm, testicular circumference should be 4 - 40 cm

Disease: EX. Epididymitis

What are the benefits of utilizing artificial insemination?

Access to better genetics

More offspring out of elite sires

Increases rate of improvement

Storing of genetic material

International movement of important genetics

Ability to breed out of season

Shorten lambing/kidding season

Bio-security

What are the 3 methods of AI used in sheep and goat production?

Vaginal AI: depositing semen vaginally

Trans-Cervical AI: depositing semen in uterine body

Laparoscopic AI: semen injected directly into the lumen of each uterine horn

What factors influence the success rate of artificial insemination?

Efficacy of programming

Female health

Semen quality

AI technician skill

What is the goal of embryo transfer?

To get more offspring out of elite females

Why go through the trouble of embryo transfer?

A) Increased offspring with elite genetics and decreased number of breeding females

B) Rate of Improvement increased

C) Increased bio-security, out of season breeding, shorter lambing season, and lamb uniformity

D) Preserving and shipping elite genetics

E) All of the above

What are the disadvantages of embryo transfer?

A) More cost and more labor intensive

B) Increased risks for donors

C) Keeping recipients on hand

D) Some females lack the genetics to superovulate

E) All of the above

T/F: Good embryos produce elite offspring even without a good recipient

False

T/F: Donors and recipients must be synchronized 3 weeks prior to the donor flush

True

Heritability

fraction of observed traits expected to be transmitted to the next generation

Low heritability is?

less than 20%

Medium heritability is?

between 20% and 40%

High heritability is?

greater than 40%

Rate of Improvement

(heritability x selection differential) / generation interval

A farmer wants to improve his herd of Rambouillet in three years. Normally, he breeds the ewes at 1 year old and bucks at 2 years old. The farmer bought a ram with better genetics and will keep the best lambs as replacement ewes. What is another way the farmer can improve his herd?

reduce the generation interval by breeding ewes and rams at a younger age.

You want to become a sheep farmer, what traits will you consider to improve your profit margin?

A) adaptability and reproductive performance

B) growth rate and carcass

C) wool quality and yield

D) all of the above

E) two of the above

What traits are considered when selecting ewes?

A) Adaptability and longevity

B) Reproductive performance and mothering/milking ability

C) Wool production

D) All of the above

E) Two of the above

What factors are considered when determining a ewe’s reproductive performance?

conception, lambing, and weaning rate

What factors are considered when selecting rams?

growth rate (most important)

fertility

aggression

type score

freedom from genetic defects

A rancher decides to improve the staple length of her Debouillet herd, so she culls the rams with lower staple length and keeps the best ewes for three generations. After these generations, she gets a slightly better profit for her lamb’s staple length. This is an example of what selection practice?

A) tandem selection

B) independent culling levels

C) index

D) economic selection

E) none of the above

A rancher decides to improve his herd of Angora goats by breeding the calmer goats that grow quicker. He decides to cull the smaller goats and the ones with horns. After breeding the first generation, half are born with horns, so he culls those too. He continues to cull the goats that do not meet his new standards. Eventually, the rancher’s goats are all calm and have an improved growth rate. This is an example of what selection practice?

A) tandem selection

B) independent culling levels

C) index

D) economic selection

E) none of the above

A backyard farmer with 30 sheep wants to raise more lambs but does not want to buy more sheep. He decides to record the breeding and weaning rates of his ewes and finds that the 10 skinniest ewes raise the most lambs. However, those lambs are smaller than the others. The farmer decides to keep half of the lambs from the skinny ewes and half the lambs from the other ewes. After a few years, the farmer has grown his herd while continuing to make a profit. This is an example of what selection practice?

A) tandem selection

B) independent culling levels

C) index

D) economic selection

E) none of the above

Index Selection Method

weigh each trait and use the complete picture rather than eliminating for one trait

Independent culling level selection method

select for several traits and cull any who do not meet the minimum level

Tandem Selection Method

select for one trat only and cull based on that trait

What does CIDR stand for?

Controlled Intervaginal Drug Release

What is the purpose of a CIDR?

A) To increase growth rate

B) To increase estrogen in females in preparation for breeding

C) To increase PMSG in females for flushing embryos

D) To increase progesterone in females and sync ovulation cycles

E) None of the above

What steps are taken to prepare females for laparoscopic AI surgery?

1) Take females off feed and water

2) Anesthetize

3) Clip and sanitize surgical site