Cattle Reproduction Flashcards
When do heifers attain puberty?
At first estrus that is followed by a luteal phase
Is puberty a chronological or physiological age?
Physiological
What can influence the age of puberty?
Nutrition, Breed, skeletal growth, environment, body weight, management
What is the average age of puberty for dairy and beef cattle?
Dairy-10-12 months
Beef- 11-15 months
When is puberty in the bull?
the age at which the ejaculate contains sufficient sperm to impregnate the cow.
Which bulls reach puberty quicker?
Holstein and crossbred bulls
How long does the sperm per ejaculate increase?
18-24 months
Are cattle photosensitive?
Mildly they may be
What do the 4mm follicles and large antral follicles depend on?
4mm-FSH
Large antral- LH
What hormone induces estrus?
E2 and decline of P4 which triggers the LH surge
What are good indicators of estrus?
Vuscosity and ferning of the cervical mucous. Uterine tone and dilated cervix
What causes the metestrus bleeding?
Estrogen increases the vascular growth of the endometrium, when E2 drops after ovulating this causes vulval discharges
When is P4 levels high and cervical mucous thick?
Luteal phase
What ways can cows in estrus be detechted?
V-Bulls or indicators on the rumps
Describe ovulation in the cow?
10-12 hours after estrus and can be sped up bu using a v-bull. Just one follicle ovulates
How long is the estrous cycle and estrus?
21 d and 18 hours
How long is gestation length?
280 days
Postpartum uterine involution is complete on what day?
45
Is vision or small more of a turn on for the bull?
Vision
Does the old or young bull service more cows?
Old because of the social ranking
What position is the calf placed in the birthing canal?
Lateral or sternal
What can improve fertility of repeat breeders?
GNRH
When is the end of the postpartum anestrus?
First ovulation after postparnum, usually not associated with estrus
What is the wave pattern of follicular development for a cow in estrus.
3 waves
How long after the LH surge does ovulation occur?
24 hours
Sperm production is highly correlated with wha?
Testicular size
How long is required for completion of spermatogenesis?
61 days
How much is ejaculated?
4-10 ml of semen that contain 1-2 billion sperm
How many days after their calf should a cow have been in standing estrus and conceive?
Standing estrus- 60 days
Conceive- 85 days
rBST can adversely affect reproduction if given when?
Before the first postpartum ovulation
