Feed additives – where less can be more

Feed additives   where less can be more. Photo RBI
Feed additives where less can be more. Photo RBI

How do feed additives react to one another? Are these synergistic effects beneficial or to the contrary, do they deliver a reduction? A puzzle, for nutritionists and swine producers alike. Dr Casey Bradley calls for more research to possible interactions.


The past 30 years have seen an explosion in the use of feed additives to improve feed efficiency and pig performance. Yet despite nearly all swine producers now using at least one such additive – and most probably 2 or more – questions about how to maximise returns from additives keep cropping up.

What is meant by a feed additive?

First, let’s define what I mean by a feed additive, which is any low inclusion ingredient that brings additional value to the diet. So in its broadest sense this can include everything from mineral and vitamin supplementation above requirements to antibiotic and non-antibiotic growth promoters, plus enzymes, mycotoxin de-activators, yeasts, probiotics, prebiotics and many, many more.

With each one offering the promise of improved production efficiency plus numerous brands competing for attention, it’s a potentially bewildering choice.

Conversations with swine producers

Even this week, many of the conversations I’ve had with swine producers have included questions about the potential gains from adding another additive to those already in the diet.

These are great questions, and the truth is that, as an industry, we don’t always have the answers, particularly when those answers differ depending on the additive and the herd.

In recent decades, researchers and nutritionists have done a great job in refining and defining optimum amino acid levels, the ratios for correct nutrient balance and potential performance gains from added fat, for example. Even the interactions between key minerals in the diet are now becoming reasonably well understood.

Adding multiple additive produces responses

Yet with feed additives, often adding multiple additives in the feed will produce an additional economic response, sometimes it’ll produce no response, and occasionally it’ll even deliver a reduction in performance!

The challenge for the swine producer is that although feed additive responses are rarely fully additive – 1 + 1 doesn’t always equal 2 – but that doesn’t mean the gain isn’t worth pursuing. After all, 1.6 is still better than 1, as long as it didn’t cost you too much to achieve.

More research to better understand responses

What’s needed is more research to better understand the responses and interactions when 2 or more feed additives are combined. A good example of this is the work carried by AB Vista and Purdue University demonstrating a 3 fold increase in return on investment (ROI) when a xylanase fed from weaning to slaughter is supplemented with a live yeast for the first 2 weeks post-weaning.

Understanding such interactions, and how they relate to specific herd dynamics is critical to making good recommendations, particularly when considering the indirect effects of feed additives on the microbiome. The role of the nutritionist, working alongside swine producers to fine tune feed additive use for each herd, is also critical.

Companies and research institutes forming partnerships

So it’s encouraging to see more companies and research institutes forming partnerships to evaluate the effects of combining feed additives, as the potential gains are considerable. Yet much of the research needed will require even more extensive collaboration between the various sectors of the feed industry, and possibly even between suppliers.

The question is, as an industry, do we have what it takes to make that happen?

Casey Bradley Swine nutrition