Depending on the planned start of calving or due dates of cows, dry cow minerals may already need to be the diet of your cows.
Dry cow minerals should be fed to cows for at least six weeks prior to the start of calving.
Having cows in the correct mineral status during the dry period will help to prevent milk fever and associated problems, such as a slow-calving, retained placenta, ketosis and displaced abomasum.
It is also important that dairy cows build condition in the dry period and are in the correct body condition score (BCS) ahead of calving.
Minerals
To determine the mineral requirements of your herd, doing some regular blood test will help to determine the mineral required.
It is also important to discuss the mineral requirements of your cows with your vet.
The mineral make up of the forage being fed to the cows needs to be considered, and it should be of high-quality.
Many problems on farms occur when minerals are fed at the wrong rate or for too short of a period, so make sure to get these simple things right.
In terms of mineral specification, the main points are:
- Low calcium (<1.1%);
- 20-25% magnesium;
- 2-5% phosphorus (P) (feed at higher rate if forage P content is low);
- Vitamin D – at least 12,000 units/100g;
- Trace minerals – copper, zinc, selenium, manganese, iodine and cobalt with protected sources included where required.
Minerals are usually fed at a rate of 120g/cow/day; if you are dusting minerals on silage it is better to do it twice-a-day at a rate of 60g.
Dry cow management
Although ensuring that cows are in a good mineral status is important ahead of calving, it is also important that cow condition is monitored.
A spring-calving cow should be in a BCS of 3.0 at calving – being below or above or below this figure will lead to an increased risk of developing one of the issues outlined above.
At this point it will be difficult to get cows into the correct condition, so these cows need to be closely monitored.