Herd nutrition through to the end of mating
It is common to see in-calf rates drop off after week 6 of mating. This tends to coincide with a drop in feed availability and/or a drop in feed quality. Because cows that are experiencing a feed restriction tend to be less likely to display heat behaviours when they’re in heat*, suboptimal herd nutrition will make it harder for you or your bulls to find the cows that are in heat.
Pages 88 and 89 of the InCalf book (DairyNZ Ltd, 2017) have tips on monitoring your herd’s nutrition, and DairyNZ’s summer management page has information on managing feed through summer.
Book your scanning dates
To get an accurate picture of how mating has gone this year, you need at least 80% of your herd to have an early aged pregnancy test result.
To get early aged pregnancy test results, cows must be scanned between 35 and 122 days of pregnancy.
You can use our when to scan calculator to see when you will need to scan to get early aged results for your cows.
Book in your pregnancy testing now to ensure you get the scanning date you need to get early aged results.
Hitting BCS targets
To help your cows get in-calf early next mating, they need to reach their target calving BCS – helping them hit this target starts this summer.
Even with exceptional feeding, dry cows rarely gain more than 0.5 BCS units in a month, so it’s important to maintain BCS through summer so that autumn’s job of getting your cows to calving BCS target doesn’t become impossible.
Your farm system will dictate what options are open to you, such as once-a-day milking and drying-off selected cows early.
Monitor and manage BCS
Monthly body condition scoring will allow you to keep tabs on BCS. Regular scoring will allow you to actively manage BCS throughout summer.
In terms of farm system efficiency, maintaining condition is more efficient than losing it and regaining it later.
The aim is to keep 85% of the herd above BCS 4.0 throughout summer. Using a BCS-accredited professional will help you to maintain objectivity.
Empty cows do not milk better than pregnant cows - research** with twin cows in New Zealand shows that empty cows did not milk better than their pregnant twin until 250 days of lactation, and the differences were small.
To help ensure your herd continues to get the feed it needs to maintain BCS through summer, remove your cull cows from your farm so that you can put your feed in to the cows you are going to keep.
Over the last few years we’ve made great gains in getting our heifers to target liveweight at 3 and 15 months.
The graph below shows the improvement in the quality of heifers being handed over for rearing at three months of age – they are, on average, 3% above the MINDA-Weights guideline for this age.
We are now also getting our 15 month old heifers, on average, to 1% above target.
Unfortunately we are falling short of the mark after the heifers become pregnant at 15 months old, as they are entering the herd as R2’s/first calvers 4% below target (on average).
This means that they are getting in-calf fast at 15 months old, which leads them having a tight calving pattern as first calvers, but they’re not getting back in-calf as fast or milking as well as expected once in the milking herd.
We often see heifers starting to fall behind weight targets in summer, so regularly weighing your heifers through this period will help you or your grazier to act quickly if liveweights drop below target. Dairy NZ has more detailed information on nutritional requirements of heifers.