|Beneath the surface
with David Law
Most farms are now halfway through calving, which is a good marker to take stock of the current situation on-farm as well as forecast how it will track during the next three months.
Calving doesn’t come without challenges, and there are a few things you may want to consider as you look back on the last month.
Has calving and cow recovery been easy so far? What percentage of cows have had retained afterbirth? How many cows have presented with clinical milk fever? How well fed are your cows? And what is their current Body Condition Score?
Metabolic issues, including milk fever and retained afterbirth, present clinically in only around 10 per cent of cases – so for every cow that presents with a clinical metabolic problem, there are 10 times as many cows that are affected sub-clinically.
In broad terms, the largest driver behind metabolic problems is a calcium/magnesium imbalance.
A lack of calcium translates to poor muscle energy, leaving cows with insufficient energy to clean herself quickly after calving.
Even sub-clinically affected cows will retain cleanings and fall victim to an infection that will need treating – creating a barrier for the cow to get in-calf easily.
Calcium is also a carrier for all minerals, so a deficiency in calcium will affect the uptake of everything else the cow is being given.
The addition of lime flour to the cows’ diet and a calcium bullet down the throat is a great way to keep their calcium levels up.
Farmers should also look at whether their cows’ nutritional needs are being met through pasture and supplementary feed.
If you don’t have a rotation plan, you can expect a problem down the track.
The DairyNZ Spring Rotation Planner is a great resource to help you work out your rotation length. See: www.dairynz.co.nz/feed/pasture-management/feed-wedges-and-rotation-planners/spring-rotation-planner/spring-rotation-planner-tool/
The online calculator will help you work out the ideal round lengths during the period between the Planned Start of Calving (PSC) and balance date, when pasture supply equals demand.
It’s important to get rotation length correct. For example, if you’re grazing cows at 20 days when the correct rotation for that time of year is 35 days, they’re grazing nutritionally-deficient feed. They are filling up on immature grass that won’t sustain their nutritional requirements.
To support your cows’ nutritional needs, it is critical you have a trace element programme in place. Cows are expected to calve, milk and get in-calf all in the space of three months, and they need everything we can throw at them to survive these three massive challenges in such a short period.
And if cows are already low, a daily trace element programme may not be enough in the first instance. You may need to give them an additional boost of copper, cobalt and selenium via injection, preferably at least 30 days before the planned start of mating. Waiting any longer means you’ll have to use a copper bullet down their throats, a far more expensive option.
Trace element plan
If you don’t invest in a trace element plan you’ll end up giving that money to the vet to fix the resulting health problems or end up culling cows because they are empty.
Investing that money in getting cows nutritionally balanced is the better, more cost-effective way of ensuring calving and mating run as smoothly as possible.
And with monthly milk testing for M. bovis, there is enough evidence to show a cow in less-than-optimum health has lower immunity, resulting in a higher chance of testing positive for higher antibodies. Our team is focused on helping farmers in this area.