Sire Fertility

Question 1

What are the sire attributes to be fertile?

Answer 1

Physical soundness, good semen quality, and good servicing capacity

Question 2

What is the phenotype of a fertile sire influenced on?

Answer 2

Genetics and environment (P = G + E + GE)

Question 3

Breeding Soundness Exam (BSE)

Answer 3

Prognostication of a sire’s ability to impregnate females

• Typically performed on sires that are used for natural reproduction in commercial herds and as a routine exam in sires for AI companies

Question 4

5 Steps of BSE

Answer 4

1. History and general info - supporting info
2. General physical exam - physical soundness
3. Physical exam of repro tract - physical soundness
4. Collection and examination of semen - semen quality
5. Evaluation of libido and mating ability - servicing capacity

Question 5

Physical abnormalities associated with poor semen quality

Answer 5

1. Feet and leg issues such as corkscrew claws, lameness, swollen hocks, etc
2. Scrotum issues such as frostbite, excess fat, scrotal-testicular adhesion, etc
3. Testes - soft testes, degenerated testes, hypoplastic, cryptorchidism
4. Epididymis - missing cauda (tail), enlarged cauda, small cauda, enlarged caput (head)
5. Other - vesicular adenitis, inguinal herniation, short penis, penile warts, penile hematoma

Question 6

Body Condition Score

Answer 6

Has an effect on consistency of testes and spermatic cord, higher BCS (obesity) is associated with lower proportion of bulls with poor quality semen

Question 7

Scrotal Circumference

Answer 7

Measure of sire fertility as testes size is correlated with semen quality

-based on age of bull

Question 8

What does traditional BSE identify?

Answer 8

Sires whose fertility is substantially affected since it is a pass or fail exam (binary response)

Question 9

Is sire fertility a spectrum?

Answer 9

Yes, but it is not a binary trait. Bulls that pass BSE may have different levels of fertility

Question 10

How often do sires in AI centers check semen quality?

Answer 10

Every sample they take, allowing for detection of subtle differences in fertility

Question 11

Sire Conception Rate (SCR) aka Sire Fertility (SF)

Answer 11

Phenotypic trait, its an estimated outcome after a certain number of inseminations

+ SRC means bull has higher rate of conception than others

Question 12

Can you compensate for lower individual fertility?

Answer 12

Yes, by increasing the number of sperm per dose (dependent on the individual)

Question 13

Compensable Trait

Answer 13

Are those that influence number of viable sperm
- By adding more sperm, you increase likelihood of fertilization occurring

Question 14

Uncompensable Trait

Answer 14

Are those that influence quality of sperm, either in morphology or genetics; something that won’t change even if you add more sperm