With most farms over halfway through calving, there’s more time to slow down and think about mating, which usually happens at the end of September or early October for most spring dairy herds. 

We want to make sure that as many cows get into calf again this season, so preparing them for mating is vital, especially for the new batch of heifers. 

Here are some tips to prepare your herd before planned start of mating (PSM): 

• BCS – We want our mixed-age cows to be at least a 4.0 BCS and our first and second calvers to be a 4.5 or higher before mating. Cattle take about 30 days to gain half a BCS on good quality feed, so preferentially feed your low BCS cows at least a month prior to PSM. 

• Trace element supplementation – Research has shown that trace elements play a role, not only in a cow’s development and production, but also in its reproductive performance. Doing pre-mating bloods allows us to see whether their ongoing supplementation is sufficient to give them the best chance of getting in-calf. Treating cows with Multimin, an injectable supplement, 4 weeks before PSM (on top of their usual oral supplementations) can lead to 3.3% lower empty rates and cows calving 3.4 days earlier on average.  

• BVD – It is very important that our yearlings, herd, and bulls are free from Bovine Viral Diarrhoea (BVD) before the start of mating, since a positive case of BVD in the herd can lead to major negative impacts on animal health, welfare, reproduction, milk production and farm economics. BVD screening, bulk milk testing, and vaccinating (especially the bulls) are some of the basic things we can do to reduce the risk of BVD.  

• Bulls – Bull selection is important to ensure the best reproductive outcomes after artificial insemination (AI). A minimum ratio of 1 bull: 30 cows, based on what’s left after AI, then doubling this number to have a half-working, half-resting policy is recommended. Having spare bulls is also wise in case of emergencies. A minimum ratio of 1 bull: 20 heifers, then 1:10-15 after a synchro programme is recommended. Before bulls get on-farm, ensure they are tested, fully vaccinated (especially for BVD) and have had a full wellness check. A quarantine drench when they arrive also ensures they are not bringing in any unwanted parasites. 

• Heat detection – At least 75% of cows should be in-heat 10 days before PSM, and 80% of cows cycling at PSM. Identifying cows that are not cycling normally pre-mating is important as this allows you to plan for intervention methods come mating time. Talk to us about which intervention methods would best suit your needs. 

Our goal is to help you get the best reproductive outcome for your herd this coming mating season. Ring the clinic if you would like to talk more about any of the topics mentioned above, or anything else related to mating.