cow oestrus cycles
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39 Terms
What produces oestrogen
Follicle
What produces progesterone
CL
What cant be palpated
Corpus haemorrhagicum
What stimulates ovaries to release Oestradiol
GnRH → LH, FSH
LH and FSH released from where
Ant pit
Half life of LH + FSH compared to GnRH
Longer
Why is oestradiol no longer given as drug
Carcinogenic so no max residue limit
Initial follicle stage
Primordial follicle
What is needed on dominant follicle for ovulation
LH receptors
What hormone before calving suppresses follicular waves + prevents cycling immediately post Calving
Oestradiol
CL post calving usually lasts how long (2w normally)
1w
What size follicle can be seen on US
>4mm
How long does CL take to mature + secrete P
6d
relationship between FSH + oestradiol
Negative correlation
How many follicular waves in high yield (negative energy balance) + why
2 - slow follicle growth
How many follicular waves do heifers have for duration CL
3
Effect of negative energy balance on LH
Inh pulsality → some follicular waves dont ovulate as less oestradiol
Repro parameters to check
1st follicle wave timing post partum
Days to oestrus
LH pulse frequency
Timing of service in relation to oestrus (better to do early than late)
11-12hrs after oestrus onset
Standing oestrus length
6-18hrs
Oestrus signs
Mucus discharge, vulva swelling, holding milk, bawling, restless, mounting, standing for mounting, sniff vuvla, chin resting, licking, bunting (head bashing), flehmen
Days post calving oestrus signs seen
85-88d
How long do cows show heat for
12hrs
Ideal time to check for oestrus
Rumination time
Mount detectors (around sacrum)
Paint/ chalk (standing to be mounted)
Kamar → colour change
Scratch cards
Cycle length
18-24d
When to check for oestrus after last oestrus
18d later
Methods to detect oestrus
Mounting detectors (Kamar, scratch card, chalk)
Records
Teasers
Chin balls
Milk P
Activity meters (accelerometers, Heatime)
Staff
What happens to rumination levels during oestrus + why
Dec - dec eating
How soon after insemination for PD
30d
AI semen location
Just Through cervix
What to Do with AI to ensure preg rate
Sperm condition + temp
Equipment
Thaw 37degress for 40sec
Dry
Where does fertilisation occur
Oviduct
Hormone that stimulates embryo growth + elongation
P
Hormone causing luteolysis
PGF2 alpha
Hormone that is released from uterus to show embryo can be kept by blocking oxytocin + PGF2 alpha
Interferon Tau
Placentome def
Caruncle + cotyledons
How long is preg CL dependent
Entire preg
Organs needed to stimulate birth
Foetal pituitary + adrenal