Planned breeding strategies – a realistic option?

Falling herd fertility is one of the major challenges facing the UK dairy industry.  As the driver of calf and therefore milk production, letting fertility get ‘out of control’ can, over a period of time, have significant knock-on effects on a herd’s profitability.  Here, vet Chris Watson, outlines the practical implementation of planned breeding strategies as one way of improving poor fertility.

The problem with the costs of fertility are they are invisible – it is not money you can rub between your fingers – it is next year’s milk production, next year’s cull cows and lost calves – not money today., he writes.  The average 100 cow herd is losing £17,500 due to poor fertility.  Heat detection and conception rates are also falling each year.  Improve fertility and you not only have a better calving interval, you can predict your higher annual milk production, reduce unnecessary culls and vet and med spend.  At the same time, genetic gain can be maintained as cows can be culled for the right reasons – old age, lameness or mastitis, not simply because they are not in-calf.

When fertility is discussed with farmers, two of the most commonly-made statements are:

•  “My cows need a lot longer before I try and serve them to allow them to recover after calving”
• “My cows give so much milk there is no need to try and serve them early”

Certainly one way of looking at it, but I tend to respond by asking whether they would like to see a saving of around £150 per cow, or receive a payback on investment in a fertility programme of at least 10:1?

It is a fact that leaving cows longer before serving them  does not make it easier to get a cow in calf, likewise all the economics published on fertility indicate it is better to start sooner rather than later.

Understanding herd fertility can be complicated as vets talk about many different measurements and numbers.  Knowing the key ones for your herd should be the starting point; only then do you know the ‘true’ situation and plan accordingly.

The problem with measuring fertility performance is the multitude of checks you have go through before accepting a figure as a good or bad achievement.  For instance if you have a good calving interval, but cull 40% of the cows getting there, then that is hardly good policy or economics.  

Look at the list of variables you have to take into account: -

In order from calving…..

• How many of the cows that calve are actually served?
• How long are cows left before they are eligible for service – voluntary waiting period?
• How many cows are served once they are eligible - heat detection rate (submission)?
• How many cows hold to a service – pregnancy rate?
• How many cows are detected repeating – heat detection rate (returns)?

….and so on until the last options are …..

• How long do I carry on serving the cows?
• How many cows do I cull as barren?

A very simple measure which gets round the first part of the list is to determine the number of pregnancies the herd is achieving. We can use a suitable time period for this measurement (say 100 days after calving) and then record what percentage of cows are pregnant – the 100 day In Calf Rate (100 day IC rate).  Provided the herd is not culling large numbers of cows before 100 days post calving this is a good measure of fertility performance.  It is a simple “yes or no” answer for each cow and 100 days post calving is a good marker for most herds.  It also gets round the problem of measuring fertility performance in the all-year-round (AYR) calving herd as determining the pregnancies by 100 days is an ideal ongoing monitor of fertility performance.

An increasing number of farmers are turning to externally-supplied programmes to assist with managing fertility and one that has been finding favour amongst clients of ours is the Intercept® regime (Intervet UK Ltd).  In essence, this is a synchronisation programme that uses fixed treatments on fixed dates to assist with both the expression of oestrus (all too often, cows are slow to come bulling),as well as successful conception and also includes therapies to assist the fertilised egg to develop into a confirmed pregnancy.

 A summary of the system is shown in the table below: -

The system delivers:

• Set days for set tasks resulting in a simple weekly routine which is easy to follow as it fits into the milking routine.  
• It forms a circular system with cows joining the programme as they become due for service and staying in the system till they become pregnant. 

On a pilot farm, the Intercept regime was tested on all cows not served from 60 days post calving.  This means that there is normal AI and heat detection from 45 days post calving, and anything reaching 60 days is synchronised and served by 70 days. 

The synchronisation protocol has effectively controlled the first service interval and submission rates. The results are shown below:

If the underlying herd heat detection rate in a herd is below 50% there are some  large economic advantages in using this type of system.

Using a synchronisation system based on “Intercept” will: -

·     Control the length of the first service interval so the cows are given more opportunities to become pregnant by 100 days

·     Replace the heat detection rate to produce an reproductive efficiency of at least 30% (30% of cows actually available for service are served) which will deliver 50% of cows pregnant at 100 days along with a likely performance of 10% of cows culled for barren and a 91 day conception interval.

The economics of this are likely to be a saving of around £150 per cow which is a payback of at least 10:1.

Conclusions – no matter how simple they sound….

• You do not get cows pregnant unless you serve them
• The more opportunities you give a cow to be served the more likely she is to become pregnant
• You give cows more opportunity to be served if you start serving early
• Synchronisation has an important economic role to play in manipulating the first service interval