Pregnancy testing is one of the routine procedures our vet practice offers to dairy farms, and one of the most valued. Using manual skills and ultrasound technology we can determine pregnancy status with a high level of accuracy, particularly if the test is done between 6 and 14 weeks post service.
Pregnancy testing is useful for a range of purposes, such as:
Determining whether a cow thought to be in calf is still that way
Predicting calving date, therefore influencing drying off and feeding decisions
Sexing calves before birth
Confidently informing culling decisions – if the cow is late or not in calf, this may be a black mark....
Assessing herd fertility performance – how many cows are in calf, and when?
Diagnosing herd fertility problems and troubleshooting
Adding value to information for sale of cows.
Getting the most out of pregnancy testing
Successful pregnancy testing is all about a team effort. This includes good planning, good management and good follow up. Contact us early if you are thinking about pregnancy testing and we can plan an approach.
Firstly we will ask you about what sort of information you are looking for. This will help define the timing of testing and number of tests required if considering a herd test. We can talk then about mating information. Accurate mating information on the day will help the vet be more accurate and quick.
Cow identification is important, whether by eartag or electronic. It is best to have this up to scratch beforehand. Recording systems are also important – you don’t want to lose the information once you have it! You may like to use our in house systems and reporting.
On the day we like to have good facilities and settled cows. Farm staff will need to be available to move cows around.
Lastly, you will want to consider reporting requirements. Would you like us to issue pregnancy certificates for individual animals? Would you like the data recorded electronically and sent to your herd improvement organisation? Would you like to generate an InCalf report such as Fertility Focus to assist your herd performance or simply a list of cows by expected calving date? Are there cows to recheck, and if so when should this be done?
Done well, pregnancy testing can become a vital part of your farm performance, improvement and profitability. Contact the clinic to deliver the service you require.
Non Cycling Cattle
Anoestrus means “not coming in to heat” and is a fairly common problem in pasture based dairy farming systems. Another common term to describe anoestrus cows is “Non Cyclers” or “NDOs” (No Detectable Oestrus). Anoestrus is an issue because we are trying to match herd lactation feed requirements with seasonal pasture supply. The more cows calving just prior to the pasture flush the better, and a compact calving requires a compact previous mating.
Having a proportion of cows not cycling at the start of mating is entirely normal, but not ideal. Assuming heat detection is OK, in the ideal situation more than 85% of eligible cows should be seen cycling at least 10 days prior to mating start. Non cyclers reduce herd reproductive performance, as many don’t get mated early, their first heat is subfertile and some don’t return to heat normally for remating.
The cause of anoestrus involves a matrix of risk factors such as
Calving date (late calvers),
Breed (Friesian, Holstein),
Body condition score (especially if light at previous calving) and
Reproductive health issues.
Managing all of the above factors will reduce the number of anoestrus cows.
Reducing the number of anoestrus cows by herd management can be highly profitable; however there will always still be a small proportion of anoestrus cows every mating, regardless of prevention strategies. Treating anoestrus cows can also be highly profitable if undertaken prior to mating and the underlying causal factors are under control.
Treatment programs for anoestrus cows using hormonal intervention are well researched in New Zealand conditions. Cows can be mated within 10 days of treatment and experience normal fertility at first and subsequent matings. The cost:benefit returns on a mob basis are normally very positive, even without consideration of the long term retention of herd genetics.
Our clinic is very familiar with all the latest programs – there are a number to choose from. The biggest trap in anoestrus cow programs is not getting organised early enough. Premating heat detection needs to start 5 weeks prior to mating start, which is only 7 weeks post calving start!!
Please don’t hesitate to contact us in good time if you are considering an anoestrus program for your herd this year.
Body Condition Scoring
Body Condition Scoring is a method of assessment of cow energy reserves. As a cow gains weight she stores energy reserves in fat and muscle all over her body. This is laid down in reliable patterns, and good operators can distinguish Body Condition to the nearest half score (15 kg liveweight). Body Condition Score (BCS) changes more slowly than liveweight, but is a very practical and popular method of assessing nutritional requirements and the results of herd management.
Scoring may be done “in the paddock” on a representative number of cows or at closer quarters such as in the farm dairy. Most assessment is visual, although at times operators might seek more precision and keep themselves accurate by putting hands on the cow to get a feel for what they are seeing.
Cows which remain within the ideal BCS zone throughout the year are proven to have significantly better milk production and reproductive performance than those outside the zone. The benefits from optimising BCS could be as much as $200 per cow per year.
In New Zealand scoring scales have been developed to put a numeric rank on cows. In NZ scale runs from 1 to 10. In practice, most Body Condition scores are in the middle half of these extremes mentioned, eg 2.5 – 7.5 would be the full range seen in New Zealand. A score is an average of up to 8 points of the cow’s anatomy, including
Groups of cows can be scored on an individual basis, where data is used for preferential management, or they can be scored “anonymously” where a group of scores is recorded to describe the mob but no records are kept against assigned cows.
Body condition score is used for a range of purposes. Mostly it is used for feed management of Dry cows, but it is also used in feeding and management of lactating cows (such as once a day milking), sales requirements (for cows bought not long before calving) and assessment of cow welfare. Targets are available for individuals (such as a minimum BCS required for transport) or for herds (such as the InCalf target to have no fewer than 15% of cows below BCS 5.0 at calving). Crucial times to score herds are prior to calving, prior to mating, mid lactation and prior to drying off.
Some of the dairy vets in our clinic do routine Body Condition Scoring as a separate task, but sometimes it is done during other jobs, such as vaccination. Some farmers can do it themselves, but often the view of an independent, qualified professional is helpful if you want to be sure.
Bulls are assumed to be fertile... – Wrong assumption!
Approximately 10% of bulls are sub fertile or infertile, and this can have devastating consequences. The causes of infertility are varied, but regardless of the cause, if a bull or team of bulls are infertile there is no way the cows will get in calf.
Using plenty of bulls provides safety in numbers, as to some extent fertile bull(s) can cover the infertile ones. However if a behaviourally dominant bull is the infertile one, you are only using one bull or if bull power is down in general then a worst case scenario can eventuate. Cows failing to conceive are not only far less profitable, but may be forced to leave the herd at a very inconvenient and costly time.
Causes of Bull Infertility
Bull infertility can result from poor sperm quality, behavioural issues or sickness and disease. Sperm quality is affected when the bull is sick, immature or aging. It takes 9 weeks from the time something affects the testicles (like a fever) to when all the sperm affected by a negative incident will have exited the reproductive tract.
Behavioural issues, such as unwillingness to mount or excessive fighting/aggression may limit a bull’s ability to mate normally and peacefully. Other sickness, deformity or disease can have major impacts on bull fertility. Lameness is one of the biggest problems. Hoof or leg damage can affect a bull’s ability or interest in mounting. Systemic disease taking the edge off his athletic abilities or viruses affecting fertility such as Bovine Viral Diarrhoea (BVD) can also become issues. Deformities such as a corkscrew penis can be invisible until the bull is seen mounting.
Finding infertile bulls
Involving the breeder or grazier in bull fertility testing is often very worthwhile. They stand to benefit by providing quality bulls, and culling out infertile or subfertile bulls early on benefits everyone. If your bulls arrive on the property untested, book them in for a test quickly, as if you are to send any back it is much better early in the season.
Most infertile bulls can be identified with a thorough physical examination and breeding capability exam. The remaining minority (10-20%) require a semen sample.
The physical exam usually takes about 15 minutes, and a breeding capability test just a few minutes if there are willing herdmates available to participate. Many bull tests include a blood test for viruses such as BVD, so technically they have to wait for the all clear.
Dealing with infertile bulls
Infertility may be temporary or longer term. Provided the cause can be rectified his fertility will eventually return. Effectively any infertility takes a bull out of play during the current season, so a lease replacement or culling option can be invoked.
Setting up for testing
A simple examination requires only a sturdy vet race and access to the back/flank of the bull. A small yard and some oestrus or restrained cows is required for serving capability testing. If semen sampling is required, no extra facilities are needed, depending on the equipment needs of the tester.
If wanting to do some bull testing, please let us know well in advance and we can ensure the day runs as smoothly as possible.
Endometritis is a reasonably common condition following calving. Much attention has been drawn to it in recent years as researchers have fully measured impact on subsequent fertility.
The latin endo means “inside” while metri means uterus and itis means inflammation.
Thus endometritis is inflammation of the inner lining of the uterus.
During calving bacteria enter the reproductive tract, and in a proportion of cows an infection persists. A common inciting cause for this is retained foetal membranes (RFM). The infection involves production of a white-yellow pus and occasionally smell. Some, but not all cows show an external discharge of pus and mucous.
Endometritis disturbs the normal hormonal function of the uterus, delaying cycling and turnover of the uterine lining. Subsequently the uterus is also less likely to support embryonic life. Reductions in submission rate and conception rate can result in reductions in pregnancy rate (approximately 25% reduction at day 21 post service). Reductions in final not in calf (empty) rates have also been reported.
Endometritis may be hidden, and this presents a diagnostic challenge. Inflammation and infection can be present in any part of the reproductive tract, and finding any pus in the vagina is considered diagnostic of endometritis. Examination tools such as a vaginal speculum or Metricheck may assist a more accurate diagnosis.
The most common treatment for endometritis is infusion of an antibiotic into the uterus. Broad spectrum injectable treatments may also work. Concurrent treatments to make the cow cycle as soon as possible are helpful. Intrauterine infusions are documented to have improved fertility outcomes.
What should I do?
The NZ dairy industry trigger point for retained foetal membranes (RFM) is 2%. If your herd exceeds this trigger or if you notice a similar incidence of vaginal discharge in the milking herd it would be good to Metricheck the whole herd. Call your vet to do this and ask them to treat affected cows. Recheck these cows 2 weeks later.
If you want to routinely check the whole herd for endometritis this can be staggered in the weeks following calving to check all cows between 2 and 4 weeks following calving. Only the affected cows get treated and rechecked.
If you simply have a few potentially affected cows, these can be examined and treated 2 weeks prior to mating. There is a certain “self cure” rate, particularly in well fed cows.
Contact the clinic or your regular vet to make a planned approach to endometritis!
Herd Fertility Programs
Herd fertility is a fundamental driver of dairy and beef profitability. A beef cow failing to produce a live calf every year is an economic disaster, and dairy cows which do not conceive within the 10-12 weeks of mating require special favours (such as winter milking or being carried over) to remain in the herd. In most dairy herds, cows failing to get in-calf are culled at the end of lactation – end of story!
It’s not just about getting in-calf either. In our pasture based systems the timeliness of getting in calf is crucial to productivity. Cows getting in calf within the first 6 weeks of mating convert our cheapest feed source (pasture) to meat and milk more efficiently, as their peak feed demand coincides with peak pasture growth. They also put grazing pressure on the paddocks, which ensures quality regrowth in late spring and early summer. Conversely, herds with slow calving patterns do not harvest pasture efficiently and later in the year it gets out of control and quality suffers– they just can’t win.
There are two big issues which make herd fertility hard to improve. Firstly success takes time. It may be months and years between making a change (good or bad) and seeing the impact of that. Secondly it is notoriously complex.
The InCalf program describes the complexity of herd fertility like a cake. There are 7-8 ingredients which must be mixed in the right way at the right time in the right measure to get a good outcome. The ingredients of the cake are:
The calving pattern prior to mating. A spread out calving puts you way behind the 8 ball.
Animal Health eg a BVD problem can disrupt herd fertility even if other factors are good.
Nutrition and Body Condition. Cows will not cycle or hold in calf if frequently underfed.
Heat Detection. If you are using AI, you must identify and inseminate the right cows!
Calf and Heifer management. The size, health and mating management of young animals is critical to them getting in calf and contributing to fertility of the whole herd.
Bull Management. Numbers of bulls and their management directly impacts performance following the AI period.
Non Cycling cows. Management of those cows not seen in heat is a critical part of mating.
Sire selection and AI. Selecting the right genetics and managing the AI program significantly influences outcomes
All good herd fertility programs involve a “continuous improvement” process. This is because it is a slow fix, not a quick fix and you need to gain and maintain for long term success. The first step in the process is assessing your current overall performance. This might involve data analysis or procedures such as pregnancy testing. Once this is done the various options for improvement can be explored and considered. The most effective and cost effective options can then be implemented before you reflect on what you did and whether you would do it again. Finally the process returns to measuring again to see whether you really have gained from all your hard work!
Herd fertility is a serious business. It does not “just happen”, but needs commitment, understanding and organisation. As a clinic we are very interested in your success in this area and we have committed significant resources to be able to offer some excellent services. Some of our farm clients would be happy to talk to you about their experiences working with us for long term success.
Synchrony programs involve hormonal manipulation of the oestrus cycle. Cows and heifers are treated to condense the cycles of a mob into a very short window. This is very useful for AI programs where a technician is only available for a short time period or the location is remote. Depending on the technology used, up to 100% of a line of stock can be mated on the same day. Not only are the current oestrus cycles synchronised, but the returns to service some 21 days later are also somewhat synchronised.
Synchronisation may be used in beef and dairy herds, and is frequently used in heifers. The benefits include more AI calves, more milk from a more compact calving pattern and an improved calving pattern contributing to less anoestrus the following year.
Bovine (cattle) oestrus always follows the hormonal sequence of falling progesterone followed by an LH/FSH surge. All synchrony programs feature falling progesterone levels. This may be from removal of progesterone device (eg CIDR) or knocking out the natural corpus luteum source of progesterone with a prostaglandin (PG).
Progesterone based programs
The progesterone based programs give the tightest degree of synchrony because they directly control the progesterone supply. They are more complex, frequently involving 3-4 yardings for separate parts of the program.
They generally involve insertion of an intravaginal progesterone device (eg CIDR) for 7-10 days. Occasionally progesterone devices may be inserted elsewhere, eg subcutaneous implants. Upon removal of the device and other injections given at the time, heat is expected 1-2 days later. Even if oestrus is not evident, ovulation is likely, and these animals can normally be successfully Fixed Time AI’d (FTAI). Frequently 100% of animals are blanket mated on day 1, with around 10% still showing heat day 2 being mated for a second time.
Progesterone based programs not only bring cycling animals into line, but they treat non cycling (anoestrus) animals, making them cycle from scratch.
Prostaglandin based programs
The PG (prostaglandin) based programs are simpler and cheaper, but the synchrony is seldom as tight. They require that the animals are already cycling.
If prostaglandin is injected during the luteal (progesterone dominant) phase of the cycle – day 5 to 16, there is luteolysis and a sudden drop in progesterone levels. Heat reliably occurs 3-5 days later. If the cycle is already beyond day 16 the cow will naturally come into heat during the next 5 days, but if she is day 1-5 she might not come on for another 3 weeks.
Prostaglandin programs require at the maximum 2 yardings of cattle – one per shot. The AI period is generally 3-5 days after the final PG shot.
Single shot prostaglandin programs expect to bring about 70% of animals on within 5 days. If these animals have been preselected as having a heat 7-14 days earlier (Why Wait program) the rate is in excess of 90%. A variation on the single shot program is to mate for 5 days, then “inject the rest”. The remaining animals show heat within the following 5days, resulting in close to 100% submission rate in 10 days.
Double shot PG programs create a batch of “PG ready” animals with the first injection. The second injection follows 11 days later, catching all animals at a similar stage. This can result in a very good level of synchrony.
Successful synchronisation programs involve solid organisation. Start with the desired calving date and work back 282 days to mating date. A month prior to that, contact your vet or technician to organise the program. You may also need to book help for yarding the cattle and a capable AI technician to perform inseminations.
Minimising stress during yarding (particularly the yarding prior to mating) has a big effect on results. Ensure facilities are adequate size and in good working order, and that you have good numbers of experienced staff working with the cattle.
Finally, ensure you have enough “bull power” for the returns. The bulls will not be very busy for about 18 days, but when the returns come on, a bull ratio around 1:8 is advisable.