Fertility problems in cattle

What are the three possible fates of the 1st dominant follicle in a post parturient cow?

• Ovulation

• Follicle turnover (evenutally ovulate) —> if in -ve energy balance

• Cystic

How can abnormal progesterone affect ovulation?

Abnormal progesterone profile can delay ovulation

• Second ovulated once and then stops due to -ve energy balance or disease

DOV1 = delayed ovulation type 1

DOV2 = delayed ovulation type 2

What can cause a prolonged CL? What would this present as?

• prolonged luteal

• Endometritis (causing failure of luteolytic mechanism)

  • Can be first CL or later one

• Farmer may present as ONO (oestrus not observed)/ NSB (not seen bulling)

How are milk yield and fertility interrelated?

• In the past as average milk yield went up, first service after calving pregnancy rate (insemination rate) goes down

• % cows ‘standing’ also declining with incr milk yield

• Now higher yield = better fertility (can have bulls producing daughters with good fertility + high yield)

• calving interval cont. to improve (shorter calving interval = better)

What is the ideal approach to detecting oestrus?

• Automated activity meters good but not as effective if a cow is high yielding, in low BCS or lame

• A lot more effective when paired with farm staff watching

Give some examples of what can cause an increase in number inseminations per pregnancy and increase in calving to conception interval

• Drop in social status

• C-section

• bad calving

• Lameness

• Mastitis

• Milk fever (and subclinical hypocalcaemia) —> tx doesn’t stop effect on fertility prevention via pre-calving nutrition vital

  

These stressors interact: e.g- high SCC and lame much less likely to ovulate then just SCC high or just lame

What does milk fever predispose the cow to?

• Difficult calving

• RFM

• Endometritis

• Sub-clinical low calcium – worst fertility too

How does lameness impact fertility?

• Have first CL and first oestrus later

• longer calving to conception

• lower pregnancy rate % from first AI

• more inseminations per conception

• Intensity of oestrus lower in lame cows

  • Not just mounting behaviours but also specific behaviours affected (e.g.- sniffing so decr pheromones)

How does mastitis impact fertility?

• Calving interval increases

• First CL and first oestrus later

• Smaller follicles

  

• Did not conceive as quickly (reduced fertility)

  

• mastitic cows take longer to ovulate if syncronised (longer to come into oestrus)

What is this graph showing?

• 2 mild- moderate problems is nearly as bad as 1 severe problem so will affect fertility

• prolonged time till commencement of luteal activity after calving

What is this figure showing?

• Reduction in non-return rate in hot periods

• Impact is greater in high yielding cows

How may animals with comorbidities have a different response to hormone treatment?

Ex- Mastitic cows take longer to ovulate if synchronised

• Will potentially produce follicle that is less mature

  • Maybe should inseminate lame/ mastitic cows at different time relative to inc activity

• Pregnancy losses after preg diagnosis to Ovsynch are higher in diseased cows

  

• Don't respond as well to PRID synchs (Lame cows don’t respond as well to a progesterone synchronisation regime)

  

Can't just inject the diseased animals to improve fertility- they have a poor quality follicle

more problems = less response to progesterone synch

What happens hormonally in terms of fertility if a cow is lame?

• Sometimes normal but increase risk of CL having lower progesterone prod and quality

Lame cows do not respond as well to a progesterone synchronisation regime

How is nutrition associated with follicular growth and ovulation?

• Higher IGF-1 (metabolism indicator) associated with better ovulation

• IGF-1 also associated with ability to produce dominant follicle

• Oestradiol production by first dominant follicle depends on IGF-1 days 1-21 after calving

• Impacts maximum diameter of follicle and peak oestradiol

How does BCS loss impact fertility?

• More BCS loss = longer to ovulate

• Poor 1st service to conception/pregnancy rate

What will cause more BCS change?

• Fat cow lose more condition

BCS at calving

How does subclinical ketosis impact repro performance?

• Decreases reproductive performance in dairy cattle

• Decreases oestrus activity intensity and duration

  

What are some important points in approaching herd fertility problems?

• Focus on problem cows in order to focus resources

• Manage/ remove risk factors for poor fertility (be aware that could be minor stressors)

What is this figure showing?

• That pregnancy rate is more related to cows served than conception rate

  • So get farm to focus on oestrus detection first to improve insemination

  • harder to incr conception rate than insemination rate