Heat detection is probably the easiest variable to influence in order to improve pregnancy rate and one or more of these aids can be used alongside visual observation.
The other variable in the equation is the Conception Rate or the ability of the cow to get pregnant after being served. The first step in investigating conception rate is to check whether the AI technique is performed correctly!
An external AI technician service should reduce the risk of this happening but if you are doing DIY AI, please make sure you do a ‘refresher’ at least every five years to avoid developing ‘bad habits’ over time. Obviously we can provide this service for you(!)
AI timing can also influence fertility. Serving cows before 40 days in milk (typical VWP) usually gets poor results as most of the cows are still in negative energy balance. In contrast, some farmers opt for delaying the first service in very high yielding cows arguing more profitability in milk production. Without entering into this technical discussion, truth is that this management decision could distort the value of the PR at first service which will look worse by decreasing the SR as these cows fall out of the window period, although the CR could be perfectly fine.
It is beyond the scope of this article to discuss the innumerable health, nutritional, environmental or genetic factors that may impact cow conception. But it goes without saying that any health issues such as mastitis, lameness or ketosis or adverse environmental conditions such as heat stress, poor cow comfort and overstocking will negatively influence reproductive performance in a herd.
Regular fertility routines play a crucial role in any reproductive strategy. Early diagnosis and treatment of postpartum disease including metritis, ovarian cysts etc., will help reduce timing to first heat after calving in order to serve the cows as soon as possible after the Voluntary Waiting Period. Another key point is the re synchronisation of empty cows or pregnancy losses (the sooner, the better!) in order to get cows re-served as soon as possible.
Make sure your fertility visits are at an appropriate frequency: ideally weekly. Vet fertility visits shouldn’t be considered an expense but an investment as they could make a huge difference in terms of reproductive success and therefore, herd efficiency.
In summary, reproductive evaluation of the herd is not just about one value and although pregnancy rate is a useful indicator, a deeper examination of the data will help to determine problem areas and design improvement strategies in order to maximise productivity. As always, if you have any questions about your fertility or anything specific in this article, please speak to your vet.