Mineral supplementation for cows is important to ensure they remain healthy during their lactation and are able to achieve maximum production.
The summer grazing season has been challenging on farms, with many farms suffering from drought conditions for an extended period of time.
This led to reduced growth rates on farms, with keeping cows fed being the main issue.
Luckily, the vast majority of farmers were able to keep their cows fed due to great growth rates in 2020, which meant excess bales were plentiful on most farms.
Mineral supplementation
During the period of stunted growth and warm weather, cows’ water intake increased and many farms increased the amount of concentrates being fed.
When this happened, it was important that minerals being fed were adjusted. Now that water consumption has decreased and concentrate feeding on some farms has too, minerals, once again, need to be readjusted.
Pica was an issue on some farms earlier in the season and still seems to remain that way in certain cases.
Common symptoms of pica are: cows licking walls, chewing stones and plastics.
Lactating dairy cows have a requirement for phosphorus (P) of between 3.2 and 4.0g/kg dry matter (DM). On average, grass provides cows with 3.6g/kg DM of their P requirement.
However, during a period of high growth rates, these levels drop slightly. This is because the rate of mineral uptake by the plant is slower than the rate of herbage production.
As a result of this, cows may show symptoms of depraved appetite or pica due to inadequate P levels in the diet.
Symptoms
If you notice symptoms of mineral deficiency consult your vet and blood test a select number of cows – a mix between heifers/mature cows is recommended.
You should also test three sample paddocks for herbage mineral levels. Cut to 4cm as per usual guidelines for grass sampling.
If a P deficiency is diagnosed, a source of P should be provided in concentrates or water supply.
To supply 5-20g P/day to cows in 1kg of concentrates/day, the ration requires 0.5-2% P.