Investigating Poor Fertility in Beef Herds

Either you have evidence that demonstrates worse performance in this season than previous seasons or you keep limited records but feel that this year is worse than others. It can be tempting to immediately blame the bull or carry out some generic blood testing without really being sure what you want to test for, but investing in a new bull unnecessarily can be costly and the expense of blood testing can also quickly rack up. We always recommend discussing with your vet before making any management changes or embarking upon investigations. In this article we discuss some key areas that may be causing you problems.

Infertility or abortion?

You finish the calving season and find that a number of your cows have not calved. This is costly as you have spent money on keeping these animals for the past year without having any return. One question that vets are likely to ask is: Were the cows pregnant initially and subsequently aborted or were they never in calf to begin with? While both reasons ultimately create the same end point, the causes may differ depending on whether we are investigating a reduced ability to get in calf or an increased risk of abortions. Pregnancy scanning your herd around 6 weeks after the bull is removed will help you make early decisions on the non-pregnant cows and also help determine what is causing a reduced calving percentage when the calving season begins.

The bull is half the herd

While it isn’t always the bull that is the problem he is essentially ‘half the herd’ in a suckler system and so it is important to confirm that he is working when the breeding season begins. We recommend carrying out a Bull Breeding Soundness Examination (BBSE) before the start of the service period. We would also consider a BBSE as part of a poor fertility investigation but as this will be retrospective it may be that the bull will pass the BBSE by the time they are tested. Figure 1 shows a BBSE report.

Figure 1

Nutrition – it’s not just minerals

Cows that are excessively under- or over-conditioned are more likely to have fertility issues. Over-conditioned cattle are likely to have problems at calving which then delays a return to normal cyclicity and so reduces the time period in which they can be successfully served. Under-conditioned cattle are likely to have problems with their reproductive hormones which will reduce the chance of coming into oestrus and increase the chance of early embryonic death. When we investigate poor fertility we therefore like to start with body condition scoring the herd before progressing to investigating specific aspects of the diet. Trace elements may well be causing problems, for example the area may be well known as being Selenium deficient or the cattle diet may be likely to be reducing the cows’ ability to absorb certain trace elements. Your vet may choose to sample cull cow livers for trace elements or, if the abattoir is some distance away, they may obtain blood samples to check Copper, Selenium and Iodine status as a minimum. To gather useful information on trace elements we would recommend testing 5-8 non-pregnant cows – it is easy to see how the testing costs add up! Other issues may be seen with Cobalt or Manganese deficiency. In reality it is seldom just one trace element that is causing a problem but this can comprise a bigger picture.

Infectious disease

You will likely have heard your vet discussing BVD (September 2021 Blog) or Johne’s disease – these are high priority diseases within Red Tractor health schemes and in the case of BVD will comprise some of the funded testing available through the upcoming Animal Health and Welfare Pathway visits. Both these diseases can affect fertility but there are many others that may also be implicated: IBR, Leptospirosis and Neospora to name but a few. You may be vaccinating for these diseases already but that doesn’t mean they are no longer creating a fertility problem. Equally if we identify Johne’s disease on your farm then there will be productivity implications but it is likely something that has been an issue for many years so may not be the only factor causing the problems you are seeing this year.

As you can see investigating poor fertility is complicated but keeping good records and being proactive can help with any investigation and hopefully mean that any problems do not have a long term impact – if you carry out a BBSE before service and discover the bull has a problem there is still time to find another bull. If you pregnancy scan soon after service you can avoid retaining non-pregnant animals, or potentially continue serving if too many cows are empty. If you wait until the next calving season then it can be hard to determine what was causing the problem at service last year or if it will continue to be a problem this year. However, if that is when you identify the problem there is still plenty that we can investigate and advise upon which will at least help with this breeding season and the next calving season.