Ruminant estrus cycle Flashcards
Normal cycle length of bovine
Normal cycle length- 21 days (range 18-24)
Estrus – 24 hours, behavior - 9 hours in notes
Estrous behavior - 7 hours in dairy cattle
- 12 – 18 hours beef cattle and heifers
Diestrus - 14 days (couple weeks) (80% of cycle)
Metestrus – 3 -4 days
Proestrus – 2 -3 days
Cattle typically produce ___-____ follicle waves per cycle
2-3
Standing behavior is produced by which hormone?
Estrogen
(bitch- estrogen to progesterone shift triggers)
Proestrus starts after
Luteolysis
Proestrus description
Starts after luteolysis
Development of dominate follicle that will ovulate.
Estrogen is the dominate hormone
Uterus starts to develop some TONE
Estrus in the cow
LH peak occurs
Ovulation occurs ~27-30 hours after LH peak/surge
Estrogen dominate hormone
Uterus is toned – feels like a rope
Behavioral estrus
Behavioral Estrus in bovine
Cardinal sign - Standing to be mounted
Secondary signs - restlessness, mounting other cows, increased activity (walking, calling), clear mucous discharge, drop in milk production
Cardinal sign of estrus in bovine
Standing behavior
Metestrus in bovine
Starts after ovulation
Uterus (early edema); softer
Ovary – cellophane ball, divot where follicle was -> Corpus hemorrhagicum
Progesterone begins to increase- remodeling occurring
Metestral bleeding – “Bleeding off”
Diestrus in bovine
CH develops into CL
CL produces progesterone- Maximum production - Days 8-9
Day 16 - PGF from uterus will begin to lyse the CL (if not pregnant)
CL not responsive to PGF prior to Day 5
The CL is not responsive to PGF prior to day…
5 of development
Sheep and goats have what type of cycle?
Seasonally polyesterous
Short day breeders
In seasonal breeders the onset and length of breeding period influenced by…
Photoperiod (#1)
Latitude and climate
Food availability
Breed (Temperate vs. Tropical)
Presence of a male
Breeding system
Physiological stage
Short day breeders in the Northern hemisphere
Generally, August through March (breeding season)
Peak is October through December
Transition periods occur around the peak (Increased frequency at the begging and end of season)
Anestrous occurs in April to May
Hormones In short day breeders, In long photoperiods (spring and summer)
Pineal gland releases inhibitory neurotransmitters to prevent/decrease the amount of melatonin being synthesized and released therefore decreasing the release of GnRH
Large quantities of melatonin being released from pinealocytes in the pineal gland leads to…
Increased release of GnRH to allow for estrus cycle to take place
In short day breeders, short photoperiods (fall and winter) lead to….
Inhibition on pinealocytes in the pineal gland is decreased and allows for larger production of melatonin. Melatonin stimulates the release of GnRH from the hypothalamus to initiate cyclicality
The goat and sheep can have between __-__ waves of follicles during each estrus cycle
3-4 is the most common for both species
Goat: 2-6 waves
Sheep: 1-4 waves
Signs of estrus in the ewe vs the doe
The ewe is more conspicuous
The doe is more obvious (tail flagging and mounting)
Cycle length in the ewe
Cycle length: 14-19 days
estrus: 24-36hours
Cycle length in the doe
Cycle: 18-22d
Estrus: 24-48h
The goal in porcine breeding is…
> 2.2 litters/sow/year with
8-9 weaned piglets/sow/year
Pig estrus cycle
18-24 (avg. 21) days
SINGLE wave of follicles
Gilts: estrus 36-48 h (1.5-2 days)
Sows: estrus 48-72 h (2-3 days)
Ovulation occurs 2/3 of the way through estrus (36 h average)
Ovulation occurs 24 h after LH peak
Multiple follicles rupture over a 1-4 h period
Estrus signs in sows/gilts
Vulva swelling and redness
Vaginal discharge
Restlessness and vocalization
Actively seeking boar
“Pricking” of ears (standing up)
Lordosis response “back pressure test”
