Bovine Therio part 1

Question 1

Dairy cattle

Answer 1

Heifers should have calves @ 2
Lactating cows should have a predetermined, economically calving interval optimized for milk production and replacement rate

Question 2

Beef cattle

Answer 2

Heifers should have calves @ 2
One calf per year
70% calvings from first cycle of breeding season

Question 3

Relationship between sire and daughter’s reproductive function

Answer 3

Sire scrotal size correlates positively with age @ puberty of daughter

Question 4

Environmental major determinants

Answer 4

Nutrition, health, proximity to bulls, season of birth

Question 5

How does nutrition affect puberty?

Answer 5

Leptin, IGF-1 and somatotropin
Kisspeptin signaling in hypothalamus impt. role in generating GnRH pulses

Question 6

Important condition that should be satisfied to have the best reproductive performance?

Answer 6

heifer development to reach 65% of mature height and weight @ breeding age 14-15 mon

Question 7

Major problems if heifers too small or too young to get pregnant

Answer 7

Dystocia and first calving @ 22-24 months of age

Question 8

Estrous cycle

Answer 8

Duration: 18-24 days
Follicular: 4-6 days
Luteal: 14-18 days

Question 9

Follicular phase

Answer 9

2 waves (3 sometimes)
Gonadotrophin dependent follicles
Phases: emergence, selection, dominance, ovulation/ atresia

Question 10

Recruitment/emergence under follicular phase

Answer 10

5-20 follicules
Transient ↑ in FSH

Question 11

Selection under follicular phase

Answer 11

↑ in estradiol and inhibin
Suppression of FSH
↑ responsiveness to LH

Question 12

Dominance under follicular phase

Answer 12

Most follicles underwent atresia
Large follicles receptive to LH

Question 13

Ovulation

Answer 13

1 follicle emerged and has the ability to ovulate if no progesterone present

Question 14

Regression (atresia) in presence of progesterone

Answer 14

Insufficient frequency of LH to cause final maturation and ovulation

Question 15

Factors that affect the length of estrus in cattle

Answer 15

PGF2a treatment (short cycling)
Ovulation synchronization and timed AI

Question 16

PGF2a admin in the luteal phase

Answer 16

Injection of PGF2a or analog (cloprostenol) causes regression of CL and estrus in 2-5 days

Question 17

PGF2a admin during recruiting phase

Answer 17

Estrus starts 5 days after injection

Question 18

PGF2a admin with follicle already selected

Answer 18

Estrus starts 3-4 days after injection

Question 19

Clinical aspects of estrus

Answer 19

Dominant follicle
High estrogen (estrodiol)
Max tone of the uterus
LH surge: maturation and ovulation

Question 20

Estrus behavior

Answer 20

Cow standing to be mounted**
Mucous, discharge, reddening and swelling of the vulva, ↑ activity, chine resting, lip curling, drop in milk production

Question 21

Length of estrus

Answer 21

15-18 hours

Question 22

Most important limiting factor to reproductive efficiency in dairy cattle

Answer 22

Heat detection

Question 23

Corpus luteum development and function

Answer 23

Luterinization of the theca and granulosa cells
Production of progesterone
Alteration of gene expression in the uterus

Question 24

Immediately after ovulation

Answer 24

Dominant follicle replaced by an ovulation depression (OVD)
Uterus has some tone or edematous
Vaginal discharge may be bloody

Question 25

Early diestrus

Answer 25

Metestrus Corpus hemorrhagicum (CH)- soft structure Uterine edema

Question 26

Diestrus (day 5-16)

Answer 26

CL cavitary or non-cavitary: crown and demarcation line with ovarian stroma (fully functional) Uterus relaxed High progesterone

Question 27

End of diestrus (luteolysis)

Answer 27

Lack of interferon tau (maternal recognition of pregnancy) Role of PGF2a and oxytocin in propagating episodic secretion of PGF2a from the uterus

Question 28

Genital examination of the cow

Answer 28

Inspect cows for abnormal demeanor, signs of lameness, mastitis, abnormal manure, vaginal discharge Body condition

Question 29

Normal uterus

Answer 29

Estrus: toned Just after ovulation: edematous Diestrus: relaxed

Question 30

Uterus abnormalities

Answer 30

Rudimentary intersex/ free martin Flaccid (anestrus) Content: pyometra Adhesions, masses, etc.