The question of trace mineral supplementation
Trace mineral supplementation is undertaken on most farms in New Zealand. To meet that demand, there are plenty of opinions out there as to what is the right amount and the right product to use. The result is a fair amount of confusion not to mention false expectations as to the likely return on investment.
The only way around the uncertainty is to take an objective approach to define the need. That is to firstly establish if there is a deficit to fill, next assess how much supplement is required to fill that deficit, and finally consider the farm system to plan the best option to deliver supplement to the animals in question. To bypass the process runs the risk of excess, reduced cost effectiveness or failure to meet the need. The steps for an objective approach are as follows:
1. Test animals from the group of interest.
2. Interpret the results considering time of year, future demand and dietary inputs.
3. Assess how much supplement is required and when.
4. Consider the farm system i.e. facilities, equipment, labour, feed system and budget.
5. Decide on the most appropriate way to supplement and the most appropriate product.
When is Enough not Enough?
There are some areas that seem to be continually up for debate. The most contentious perhaps is what level in the blood or liver constitutes enough. Time and again the production-response trials undertaken in New Zealand have failed to demonstrate a further economic response when levels are lifted above the marginal range. If a decision is made to lift levels well above the marginal range, expectations should be realistic. Improved performance beyond what is achieved at the point of sufficiency is unlikely and cost-effectiveness is reduced.
In the planning process described above the decision to lift levels well above, the marginal level may be valid where a period without supplementation or high demand is anticipated. The obvious example of this is the liver copper level in mid to late autumn. Because the liver acts as a reservoir and will maintain normal blood levels and meet normal production requirements even while the liver is being depleted, it is reasonable to use this to our advantage. However for other trace minerals this is not a valid approach.
Organic versus Inorganic
Organic versus inorganic is another bone of contention. Good trial data comparing these in our pastoral based system are still largely missing. Most of the work is from overseas in cows on cereal-based diets and even in these trials the results are variable. A fair summary of what we know is that organic chelates will provide some advantage in situations involving antagonisms e.g. molybdenum, sulphur, iron or zinc interfering with the uptake of copper. As a result, the benefit cannot be guaranteed in all situations and is likely to be at best modest in most other situations.
Make trace minerals part of your annual animal health review with Totally Vets.
