Fertility in cows Flashcards
What is a fertile cow?
A cow which meets the fertility criteria established for the herd/unit
What can be considered as an infertile cow?
Sub-fertile is one that fails to achieve it’s fertility target of herd/unit
Infertile refers to a cow which is incapable of becoming pregnant (sterile)
What is the relationship between milk yield and fertility?
As milk yield goes up fertility decreases
What are the signs of sub-fertility?
No observed oestrus - Return to oestrus after AI or natural service - Abnormal vulval discharge - Abortion and stillbirth
What reasons are there for no observed oestrus?
Congenital abnormalities causing ovarian agenesis, hypoplasia and freemartinism - Acyclical/anoestrus - Limited behavioural signs - Failure of detection
What is freemartinism? How does it occur and how is it diagnosed?
Small vestigial tract with no ovaries - 92% of female calves who are twinned with bull calves - Use ‘thermometer’ test inserted into genital tract (goes 2-5cm)
What would you see on clinical examination of an anoestrus/true acyclicity?
Rectal palpation shows involuted tract; small, smooth and flat ovaries - Ultrasound shows follicles with no CL - Low milk progesterone levels
What can cause anoestrus/true acyclicity?
High milk yields - Inadequate feeding especially energy - Poor body condition - Stress (lameness, intercurrent disease)
How does reduced nutrition influence fertility?
Reduced IGF-1 influences Hypothalamus (reduced GnRH) Pituitary (reduced LH and FSH) Ovary (reduced granulosa proliferation, steriodogenesis, luteal activity) Embryo (reduced embryo growth and IFN-alpha production)
What is the treatment for anoestrus/true acyclicity?
Return to positive energy balance - Hormonal treatment (Progesterone Releasing Intravaginal Device PRID and Controlled Internal Drug Release CIDR) - Improve nutrition concurrently
What are three common abnormal structures found within the ovary?
Lutenised follicles - Follicular & inactive cysts - Luteal cysts
What are the three types of ovarian cysts? What are the features of each?
True follicular cyst - thin walled, oestradiol secreting
Luteal cyst - Thick walled, progesterone secreting
Inactive cyst - Thin walled, functionally inactive
Why do cysts occur? What causes this?
Absent LH surge (hypothalamic/pituitary) - Failure of oestradiol to elicit normal positive feedback (hypothalmic/pituitary) - Reduced numbers of LH receptors (ovarian) - Low insulin and IGF-1 which impares follicular cell proliferation & function
How do you treat an ovarian cyst?
Cysts formed in immediate postpartum period will regress spontaneously - DO NOT RUPTURE - Luteal cysts with PGF2a - Follicular cysts with GnRH
What are the cardinal signs of oestrus?
Restlessness - Standing to be mounted - Vulval discharge
