Conception Failure

Question 1

Conception Failure

Answer 1

No fertilisation occurs
Due to:
* Mistiming of mating
* Ovulation failure
* Male infertility

Question 2

Embryonic death

Answer 2

Loss of embryo before organogenesis is complete
Fertilisation occurs
* Chromosomal abnormalities
* Losses in oviduct
* Impaired embryonic development and failure to be recognised by mother
Can’t block luteolysis so CL regresses and progesterone falls
* Implantation occurs but pregnancy is lost

Question 3

Early pregnancy loss in cattle

Answer 3

○ Very significant cause of subfertility
○ Pregnancy losses up to 40%
○ More common in dairy cows
○ Associated with high yield/NEB
○ High economic cost

Question 4

Early pregnancy loss in Sheep

Answer 4

○ Uncommon, sheep have a high fertility
○ Management issues
Over-use of ram
Particular breeding strategies
○ Multiple conceptions - may only lose one

Question 5

Early pregnancy loss in pigs

Answer 5

○ Significant
○ Associated with ovarian pathologies after weaning
○ Physical uterine capacity

Question 6

Early pregnancy loss in horses

Answer 6

• Significant but fertilisation rates high
  Pregnancy loss up to 24% - most occur before day 12
• Loss can still occur after this and associated with lack of embryonic mobility

Question 7

Early pregnancy loss in dogs

Answer 7

• Uncommon
• More likely mis-timing of mating
• Non-pregnant dog will have pseudopregnancy

Question 8

Early pregnancy loss in Cats

Answer 8

• Uncommon
• More likler conception failure due to inappropriate mating

Question 9

Reasons for conception failure in cattle

Answer 9

• Metabolic or physical stress
• Ovarian pathologies (cysts)
• Lack of oestrus detection
• Mis-timing of AI

Question 10

Nutritional Causes

Answer 10

· Negative energy balance leading to low IGF1 and growth factor support to ovary / uterus
· High NEFA: toxicity to ooycte
· High protein leading to elevated urea concentrations
· Mineral and micronutrient deficiencies

Question 11

Other causes

Answer 11

• Impaired embryonic development
• Heat stress (above 25C)
• Infectious causes
• Damage to endometrium

Question 12

Infectious causes

Answer 12

Campylobacter
BVDV
BHV1

Question 13

Damage to endometrium causes

Answer 13

Subclinical mastitis
Delayed endometrial repair

Question 14

Early embryo mortality in cattle

Answer 14

Failure to secrete maternal recognition signal (IFNT)
Due to:
* Lack of progesterone
* Attenuated uterine secretion of histotroph
No product licensed but could stimulate progesterone production (GnRH/hCG) or supplement with progesterone

Question 15

Embryonic death in sheep

Answer 15

Associated with multiple conceptions - embryo loss before implantation unlikely to affect pregnancy
Infectious causes:
○ Toxoplasmosis
○ Schmallenberg virus
○ Border disease
Nutrition:
○ Flushing to optimise number of ovulations
○ Grazing of red clover around mating:
High phyto-oestrogen content can have negative effect

Question 16

Failure to establish pregnancy in pigs

Answer 16

• Seasonal effects - decreased fertility in summer and autumn
• Ovulation failure - cystic ovarian disease, particularly after early weaning, stress and under-nutrition

Aim is to re-establish pregnancy within a week after weaning
* Peak fertility observed in pigs with 3-5 days weaning to oestrus interval

Infectious causes:
* Porcine parvovirus (PPV) - causes resorption/mummification