8 September 2025

6 minute read

By: Sarah Mikesell

Dr. Bart Borg, vice president of feed and nutrition at Passel Farms, and Dr. Aaron Gaines, managing partner at Ani-Tek, spoke to The Pig Site’s Sarah Mikesell at the Lessons in Swine Nutrition seminar titled Late Finishing Swine Nutrition: Listen to the Pig, hosted by U.S. Soy. This research was presented by Dr. R. Dean Boyd, with Drs. Borg and Gaines providing commercial perspective.

Dr. Borg, what is the most critical consequence of feeding high levels of synthetic amino acids in late finishing diets?

The late finishing impact of high levels of crystalline amino acids would be in feed conversion, which, depending on input cost, can be an expensive mistake to make.

Over the finishing period, just to put some economics into this idea, a point of feed conversion would be about $0.10 per point per hundredweight. If we are talking about three or four points, you end up rolling up some significant losses.

Dr. Gaines, why is it so important for younger nutritionists to hear this message today?

For younger nutritionists, it's important to hear the message because they're taught to formulate to a minimum essential amino acid ratio, but they also need to be mindful of not getting too aggressive with synthetic amino acids even though they're meeting the essential amino acid ratio. Because what we find is that if we get too aggressive, particularly in the late-finishing pig, we're going to lose growth performance and/or feed conversion.

Dr. Borg, how should practical diet formulation be handled to avoid feeding elevated levels of synthetic amino acid levels that could compromise growth and profit?

There are several ways that could be managed, but the way that I would do it would be to put a maximum amount of lysine on the formulation itself, which varies depending on weight of the pig. Then the program itself will look for the other sources of lysine, and in this case, watching soy come into the picture to supply that additional lysine.

Dr. Borg, in your current position as VP of nutrition at Passel Farms, is your objective to maximize profit or achieve least costs?

Certainly, it is to maximize profit because we can quickly go broke saving money. The objective is to be aware of the ingredient prices, the input costs that we have in corn, soy and DDGs primarily. Then be mindful of what market we're selling into out into the future.

Right now, we have some nice prices in July and August that we hope will extend into fall, but with the input costs that we have today, it’s a profitable time for maximizing the performance of the pig.

Is that different from your previous position on the feed supplier side?

It can be. It's important in feed sales or technical service, which is what I was doing, that you're reading the customer. In some cases, people just want the absolute cheapest, and they're not worried about or don't want to think about performance aspects.

Obviously, if you're in pork production for the long run you need to make some money. You can formulate diets to make them look cheap, or you can present the whole picture. My strategy was to present both and hope to be able to convince the producer to be on the profit side of the equation.

Dr. Gaines, some might consider this data to be a little old. Is there any reason to think the barrier to high synthetic lysine use in early to late finishing has been resolved?

United Soybean Board (USB) recently sponsored a study that was done at The Maschhoffs in cooperation with Kansas State University and the University of Missouri. They looked at minimum soy levels in corn-soy diets and corn-soy-distillers’ diets in both the grower and finishing phase.

They found there was still a minimum amount of soybean meal required in the grower diet and the finishing diet. In the finishing diet, the minimum soy was still more important. It's very detrimental if you get too high levels of synthetic amino acids and don't have some minimum soybean meal level in the diet, regardless of diet type, whether it's a corn-soy diet or a corn-soy-distillers’ diet.

In a corn-soy diet, that minimum is higher than in a corn-soy-distillers’ diet, so you can feed a little bit more aggressively, perhaps, in a corn-soy-distillers’ diet than you can a corn-soy diet.

What's the current hypothesis on why high levels of synthetic amino acids cannot be fed to late finishing pigs?

Dr. R. Dean Boyd discussed this earlier today, talking about essential amino acids that we don't understand very well – or maybe even non-essential amino acids. From the study he presented, that doesn't appear to be the case. Then you start thinking about what's unique about soybean meal.

We know soybean meal contains functional compounds, whether they are isoflavones, saponins or maybe some of the peptides that get broken down by the pig. It looks like there's something unique about soy which is why we must keep some minimal level of soybean meal in the diet for the pig. I think that's an area of research that we need to understand better. We need to know what is unique about soybean meal as an ingredient.

What additional research is needed to address limitations of utilizing elevated levels of synthetic amino acids and late finishing pigs?

We have been working on this problem for 25 years, and we still haven't solved it. For the graduate students that are listening or the professors at the university, this is where we need help – in terms of figuring out how do we feed more synthetic amino acids especially, to the late finishing pig? More importantly, we need to understand what's unique about soybean meal, and why we must have some minimum level of soybean meal in the diet.

Dr. Borg, what are the key takeaways for nutritionists and swine producers to know from your events today?

The one takeaway is the importance of not just looking at diet cost but having both the input costs and forward thinking of what kind of market I am producing weight to sell into. Sometimes that price isn't high, so there are some things that we unwind at that time to reduce costs.

Right now, it is not that time – we've got some profitability in front of us. Input costs, including soy, are at multi-year lows, so it's a time to be aggressive by putting weight on and especially during the summer months.

Dr. Gaines, what is your key takeaway?

Nutritionists really need to pay attention to minimum soybean meal levels. Essential amino acid ratios are important, but we also need to be mindful of minimum soybean meal levels in pig diets as well, particularly in the late finishing pig.

For more information, please click here.

ussoy.org

© 2025 United Soybean Board

U.S. Soy is a federally registered trademark of the United Soybean Board and may not be used by third parties without explicit permission. Brought to you by U.S. Soy. Fully funded by the Soy Checkoff.