I went to a DairyNZ field day last week where the results of an investigation into feed conversion efficiency were presented. Some animals just manage to achieve more production from less food eaten with the difference between the best and worst highly significant – so it’s well worth a look at the issue.
The researchers found that the contribution played by genetics to the difference between the best and worst performers was between 14% and 19%. It was concluded that further research to explore the possibility of breeding for this higher efficiency was worthwhile.
However, research dollars are limited and choices need to be made. So, is it better to pursue the genetic line or is it better to look at the 81% to 86% of the cause of difference that is not genetic i.e. environmental influences? “Environment” in this sense isn’t climate change or saving the whales but what exactly is happening in the animal related to its diet, stressors and stress level, production level etc. There is an opportunity to improve the feed conversion efficiency in the animals we already have now, not at some undefined point in the future when the vagaries of genetic gain might eventually come into play.
One interesting aspect the researchers found was that the lesser efficient animals converted more of their energy intake into heat rather than growth or milk production. Immediately we are talking about thermoregulation - the process that animals use to control their heat production and how they partition energy between keeping warm and growing or making milk.
There has been quite a bit of work done on thermoregulation. The thyroid gland and corresponding thyroid hormones play a very important role here. If we take a cursory look at what influences the effectiveness of these processes, we immediately find a tie up with two trace elements that are more often than not deficient; iodine and selenium.
Iodine is the core of the thyroid hormones and selenium is actively involved in the conversion of inactive to active forms of these same thyroid hormones. And incidentally, the level of selenium required for full activity of the proteins needed for this conversion is around 10 times higher than the currently accepted dietary selenium minimum i.e. status quo advice regarding selenium intakes will result in less efficient thyroid function and less efficient thermoregulation.
Poor feed conversion efficiency is already high on the list of effects that iodine and selenium deficiency are associated with – nothing new there. The initial work done to identify the genetic versus the environmental contribution to feed conversion efficiency has been extremely valuable. But where will the research dollars return the most benefit – the 80 plus% environment or less than 20% genetic? That’s a strategic question for those who approve the funding. In the meantime, the rest of us can ensure our stock are eating a diet that is sufficient in iodine and selenium and we may just head the scientists off at the pass.