Module 3: Management of Ruminant Breeding Stock

Question 1

single most important factor affecting the economics and profitability of beef cattle breeding operations.

Answer 1

reproduction

Question 2

Measures for the Bulls include;

Answer 2

• physical and structural soundness
• scrotal size and sperm production capacity
• semen quality, including morphology
• serving ability/ serving capacity

Question 3

Measures for the cow include;

Answer 3

• weight and age at first estrous cycle
• the inter-calving interval
• lactation status at subsequent pregnancy diagnoses

Question 4

Measures for the breeder herd include;

Answer 4

• branding and/or weaning rates
• kilograms of calf weaned per 100 kg of cow mated
• conception rates determined by pregnancy diagnoses (PD)

Question 5

limitations to the above measures include;

Answer 5

• fertility cannot be assessed directly for bulls
• pregnancy status for cows required skills in pregnancy diagnosis
• branding and weaning rates do not provide
• unless birth dates are known and a restricted joining period
• important to consider that these rates must be calculated

Question 6

benefits of calculating reproductive rates;

Answer 6

1. identifying the importance of age, weight, body condition and lactation status
2. identifying how management, nutrition, and breeding practices can be modified to optimize fertility.
3. making an assessment of wether disease status of both cows.

Question 7

Bull costs per calf weaned will depend on;

Answer 7

1. purchase price
2. bull salvage value at ultimate sale
3. number of breeding seasons that involve the bull
4. whether bulls are checked annually for soundness and fertility
5. number of cows per bull
6. weaning percentage achieved;
7. bull mortality rates

Question 8

four key components of bull breeding soundness evaluation (BBSE)

Answer 8

i. physical soundness
ii. scrotal size
iii. semen assessment
iv. serving ability

Question 9

to provide an indication of likely fertility

Answer 9

bull breeding soundness evaluation (BBSE)

Question 10

assessing a bull’s structural soundness should include a systematic examination.

Answer 10

Physical (structural) soundness

Question 11

physical (structural) soundness should include a systematic examination of what;

Answer 11

eyes, and surrounding areas, jaws, mouth and teeth, limb structure, joints, stance, gait, hoof, and claw structure

Question 12

common problems of physical (structural) soundness include;

Answer 12

post legs, sickle hocks, swollen and puffy hocks, bow legs and cow hocks.

Question 13

the major factors influencing scrotal size include;

Answer 13

i. genotype
ii. age
iii. liveweight
iv. nutrition
v. timing of nutritional stress

Question 14

common conditions that interfere with fertility and can be diagnosed by palpation of testicles include;

Answer 14

1. unequal size of testicles
2. hardness of one or both testicles
3. thickened scrotal skin
4. softness and flabbiness of testicles and tail of epididymis

Question 15

scrotal size is a useful criterion for assessing bull fertility for the following reason;

Answer 15

1. easily measured and is repeatable
2. related to a bull’s own fertility
3. genetically correlated

Question 16

Key components of bull fertility;

Answer 16

1. Bull Breeding Soundness Evaluation (BBSE)
2. Physical (structural) Soundness
3. Sheath, prepuce and penis
4. Semen and Spermatozoa
5. Libido and Serving Ability

Question 17

is the sexual desire of a male to serve a receptive female.

Answer 17

libido

Question 18

provides an indication of the bull’s ability to serve.

Answer 18

serving-capacity test

Question 19

Puberty is defined as the time when a bull is capable of producing 50 million live sperm per millilitres.

Answer 19

Sexual Maturity

Question 20

other factors affecting bull fertility

Answer 20

sexual maturity, diseases, nutrition, bull wastage

Question 21

factors influencing when bulls reach puberty include;

Answer 21

1. genetic effects
2. nutritional influences

Question 22

such wastage can be due to a large number of factors, including;

Answer 22

1. structural defects
2. degenerative conditions
3. age structure
4. reproductive abnormalities
5. infertility due to testicular degeneration
6. infertility due to disease effects
7. traumatic injuries due to fighting

Question 23

a veterinarian should carry out a BBSE to examine bulls for soundness - prior to sale or purchase, and annually for existing bulls. Such an examination involves.

Answer 23

1. checking that the bull’s overall structure (legs, feet, and external reproductive organs) are free from defects.
2. assessing the sheath, scrotum, and testicles
3. measuring and recording scrotal circumference
4. palpating of the testicles
5. collecting a semen sample

Question 24

Reproductive events in the female are marked by;

Answer 24

1. expression of estrus
2. ovulation and fertilization of the ovum
3. implantation, growth, and survival of the embryo and fetus
4. maintenance of pregnancy
5. birth and survival of a viable calf
6. adequate lactation for calf survival
7. early return to reproductive activity

Question 25

signs of estrus include;

Answer 25

1. behavioural changes
2. swelling and reddening of the vulva
3. vaginal mucus discharge adhering to tail and legs
4. abrasion of skin
5. ruffling of tail hair
6. increased tone

Question 26

the average duration of estrus is 6-18 hours; being slightly shorter for heifers. the length of estrus is affected by:

Answer 26

*breed
*nutrition
*temperature stress
*age
*ovarian abnormalities
*uterine infections