Infertility in the Individual Cow

Question 1

On your routine visit you are presented with a dairy cow that the farmer hoped would have been pregnant by now. What kind of things do you need to know to find out what’s going on? (5)

Answer 1

· Has he seen her show oestrus behaviour? How does he detect oestrus? Key question; if she is showing oestrus, and gets served but does not conceive this will rule out issues with poor heat detection/submission issues, which is an important cause of poor fertility performance on dairy farms. If she’s not been seen cycling, it is important to determine how heat detection takes place (who does it, what do they look for, any tools (scratchpads, activity monitors, tail paint etc) being used?

· Is this an individual or a herd problem? If the herd has problems as a whole, infectious/management related causes are much more likely to be causing a problem, compared to anatomical/functional individual causes such as neoplasia or other acquired disorders.

· Has she calved before, was calving uneventful? Anatomical damage or infection due to for example dystocia or a forced extraction may interfere with future fertility, although unlikely to be at the ovarian level.

· Has she shown any other abnormalities/disease? Signs of disease may help you prioritize the different causes on your differential list; i.e. if there have been respiratory signs attributable to IBR; this make fertility related problems due to IBR more likely.

· How many days in milk is she and what is her current yield? If she’s an average yielding cow with plenty condition on her, it is less likely to be an energy related issue, compared to when she would be a top yielding cow putting all her energy into milk.

Question 2

In this case herd performance is excellent, and it appears to be an individual cow problem. She is a second calver, 60 days in milk, BCS of 3, producing 25 litres (which is below average for the herd) and the farmer has not seen her in oestrus at all since calving. Her calving was uneventful and the farmer can’t remember any specific issues with her after calving.

Assuming the farmer’s oestrus detection is pretty good; which of the following differential diagnoses would be the most likely explanation for this cow’s lack of oestrus/pregnancy?

Answer 2

Anoestrus due to the presence of risk factors such as endometritis, pyometra, cystic ovarian disease, lameness

Question 3

Consider true anoestrus for a minute; let’s assume you find the following on rectal examination?

· Two pea size ovaries

· No active corpus luteum

· Normal vagina and vulva

· Uterine horns and cervix fully involuted

Do these findings on their own confirm ‘true anoestrus’?

Answer 3

No

Question 4

What can we do about anoestrus?

Answer 4

This depends of the underlying cause, and may sometimes be as simple as removing the calf in beef suckler cows.

Treatment is often a bit more tricky and success rates of pharmacological interventions are variable. Considering the underlying causes will help you understand why; if the cow is in a negative energy balance, has (sub)clinical ketosis, a uterine infection, or other concurrent clinical disease, and we don’t address those issues, our attempts to get her in oestrus will likely be unsuccessful.

Question 5

However, if we manage those issues, what can we do pharmacologically to encourage this cow to start cycling again?

Answer 5

Insertion of a progesterone releasing intra-vaginal device for 12 days (e.g. PRID or CIDR)

Question 6

Let’s assume we performed a rectal examination on the cow before considering any of the anoetrus treatment options and found the following:

Which later in the abattoir may have looked like this

She went to the abattoir for other reasons, but this cyst was causing her anoestrus issues.

Cystic ovaries are a common problem in dairy cattle, incidence from 5-30% is recorded. This is much lower in beef herds (<5%). The agreed definition of a cyst is a fluid filled structure >25mm in diameter, persisting >10 days, in the absence of a CL.

Subluteal levels of progesterone are often observed in high yielding dairy cattle, especially when energy compromised. This leads to inadequate formation of LH receptors, which leads to decreased sensitivity to LH of the growing follicle, which creates a persistent dominant follicle/cyst, leading to anovulation and anoestrus.

Cysts can present as follicular and luteal; it is now believed that the thin-walled follicular cysts are early stage cysts (which may produce oestrogen and can cause nymphomania). The luteal cysts, which are more commonly observed, are thicker walled and secrete progesterone. On ultrasound you may find trabeculae across the central lacuna.

What are we going to do about this cow with cystic ovarian disease (COD)? (4)

Answer 6

Insertion of a progesterone releasing intra-vaginal device for 12 days,

Inject GnRH and PGF2a 7-14 days later,

o This may work for follicular cysts; increases FSH and new follicular wave, which would create a corpus luteum to lyse 7-14 days later after which normal ovulation of a dominant follicle should occur.

PGF2a,

Ovsync protocol (day 1 GnRH, day 7 PGF2a, Day 9 GnRH, with optional progesterone device from day 1-8)

o These options become more expensive/labour intensive, however when not certain if the cyst is follicular or luteal (which is not always obvious on ultrasound), a combination will cover both options.

Question 7

It is important to be aware of the treatment success of any intervention (as it does add cost in drugs and time spend treating these COD cows). Have a look at Table 22.13 in Veterinary reproduction and obstetrics, Chapter 22, p.447; 78% of cows with cystic ovaries that did not receive treatment got pregnant, for the treated groups (PGF2a, GnRH and progesterone) this ranged from 81-89%. Do you think that improvement is sufficient to warrant treatment?

Answer 7

It highlights that underlying issues are crucial to consider when managing herds with a high incidence of COD; the Figure below highlights where NEFA’s, NEB etc play a role and how that interferes with normal follicle development.

Question 8

What is the pathogenesis of cystic ovarian disease?

Answer 8

Question 9

Considering follicular and luteal cysts (luteal cysts are more commonly observed); what clinical signs are most commonly seen in cows with ovarian cysts?

Answer 9

No observed oestrus behaviour

Question 10

Define repeat breeder

Answer 10

The definition of a ‘repeat breeder’: >3 inseminations and not pregnant, with repeated regular returns; she typically has normal inter-service intervals, no evidence of clinical disease and examination of genital tract is normal.

Question 11

What can cause the repeat breeder not to conceive? (8)

Answer 11

· Poor semen quality

· Luteal deficiency, i.e. low progesterone levels

· Oviduct obstruction (due to i.e. salpingitis)

· Poor uterine environment

· Impaired embryo development

· Poor conception due to delayed ovulation or an extended follicular phase

· Poor AI technique

· Infectious causes such as BVDv, BHV-1 (IBR) and Leptospira hardjo

Question 12

All these options are possible explanations for a ‘repeat breeder’; good history taking and a clinical examination (rectal & vaginal) will help you rule out some of the causes, although you won’t always be certain about the underlying reason.

There are various suggested treatment options for repeat breeders, aiming to improve the uterine environment and embryo development. As you can imagine, their success is highly dependent on the underlying reasons discussed previously. When management and disease have been ruled out, one could consider manipulating the uterine and ovarian environment in the following ways; match the strategies below with the appropriate treatment.

1. Increase progesterone when luteolysis is expected
2. Augments LH surge, enhances CL function
3. Use a different uterine environment to improve chance of embryo successfully embedding in the uterus
4. Enhances CL function throughout the period of maternal recognition of pregnancy n

Answer 12

1. Increase progesterone when luteolysis is expected - Intra vaginal progesterone device for up to 10 days after AI,
2. Augments LH surge, enhances CL function - GnRH at insemination,
3. Use a different uterine environment to improve chance of embryo successfully embedding in the uterus - Embryo transfer,
4. Enhances CL function throughout the period of maternal recognition of pregnancy - GnRH 11-13 days post insemination

Question 13

By using products containing progesterone, PGF2a and GnRH we can influence submission rate by designing synchronisation protocols to manage service.

Would you think these protocols can be used on beef farms?

Answer 13

It would mean beef farmers would use AI instead of natural service.

Question 14

List reasons why beef farmers would use AI and how synchronisation protocols may benefit them. (6+)

Answer 14

· The ability to use sires of superior genetic merit (the best bulls of the breed);

· Improving production traits in cattle operation;

· The ability to mate specific sires to individual cows;

· Reducing the number of herd bulls needed in cattle operation;

· Increased genetics for replacement heifers;

· When combined with estrous synchronization, a shorter calving season can be achieved, resulting in a more consistent, uniform calf crop.

By using AI beef farmers avoid bull costs, and bull management. They avoid inbreeding by being able to use semen bulls worldwide. AI give them the opportunity to utilise superior genetics.

By using synchronisation protocols they can synchronise oestrus which makes cows easier to spot, and is an efficient way to get cows bred by blind AI (without looking for oestrus) who are the rest of the time out at grass and difficult to observe for heat (compared to dairy cattle coming into the parlour every day).

The consequence is that the farm needs to have excellent management facilities and space to be able to manage the cows and calf crop within a very short period of time. It is therefore not an option that suits everyone.