Questions remain regarding the mechanisms behind many of the ingredients used in swine diets, said Gerald Shurson, professor of swine nutrition at the University of Minnesota.
He said it may be time for nutritionists to use different tools to get to the bottom of the functionality of such feedstuffs.
Shurson told FeedNavigator an integrated animal systems biology team has been set up to better understand the physiological, biochemical, gene expression, and immunological pathways and processes involved in the interaction between an animal’s intestinal tract and components of feed ingredients or additives like organic and inorganic trace minerals, direct-fed microbials, and prebiotics in a more complete, or holistic way.
“We can make some general inferences but we often can’t get to the cause and effect of responses,” he said. “Using more of the organ and whole animal-based “omics” [analysis] approaches allows us to discover new biomarkers and a more complete picture enables us to better understand what is going on.”
"By using a more system-based approach to include the interactions between the microbiome and changes in gastrointestinal physiology, gene expression, and metabolomics, we can find changes in patterns and shifts in whole body metabolism and regulation from various nutritional interventions that can give us better clues to truly discover how various feed additives and dietary components work – which may be different than some of the more generic indicators we have focused on in the past," he added.
The team is looking to break down the silos in research work, incorporate members from different fields and use new technology to better understand the current tools available to producers, he said.
“The whole food production system continues to evolve and science has to keep up or stay ahead of the challenges,” he said. “How do we participate in this in a more meaningful way than we have in the past?”
Nutritional efficiency
The overall goal in work to improve swine nutrition is to increase caloric intake and boost nutritional efficiency, said Shurson.
One of his team's more recent research projects focused on swine involved characterizing gut physiology, hormones, gene expression, immunology, and energy contributions of various types and amounts of dietary fiber.
The project looked at the use of high fiber byproducts in feed like dried distillers grains with solubles (DDGS) that have a higher gross energy content than corn, but less net energy available to the animal, he said.
“The key question is how do we convert more of that gross energy into net energy that the animal can use,” said Shurson. “We have to fundamentally start understanding how different types and amounts of fiber are utilized and affect whole body responses beginning at the gastrointestinal level.”
That work is part of a larger conversation about establishing a better and more complete understanding of the role that fiber plays on energy utilization interactions with other nutrients, as well as the potential role it may play in reducing immune challenges, improving gut integrity, influencing the nature of gut microbiota and other issues that influence how the gastrointestinal tract functions, he said. “Different compounds and raw materials have a big influence on these responses and mechanisms that contribute to them need to be discovered,” said the academic.
“From a fiber and lipid point of view, we have to understand how various characteristics of these dietary components are utilized by the pig when we formulate diets,” he said. “We’ve got good at customizing diets to meet the specific nutritional needs of pigs under various types of commercial farm conditions, but now we have a whole other set, a layer of things that need to go into these decisions – what fiber type should we use? Is there an optimal level of dietary fiber? Do we use enzymes and will they work? Is the response predictable? Will the benefits outweigh the cost?”
Unanswered questions
Questions remain about the impact of by-products like discarded oils or dried distillers grains, or functional ingredients like phytochemicals and various feed additives in animal growth and what secondary systemic effects they may have, said Shurson.
“Lipids have a lot more energy compared to carbohydrates from a total calorie [perspective], but if they’re heat damaged, their energy value is likely reduced and the peroxidation compounds present can likely have adverse health effects,” he said.
Additionally, much of the work with functional additives has been an examination of if they cause a change or not, said Shurson. “There have been a lot of reviews - what is missing from these reviews is ‘why do they seem to provide benefits sometimes and not in others?’ To answer this question, we need to fully understand the mechanism of what they do when we put them in various diets and feed them under different health challenge situations,” he added.
A longer-term project for the integrated team will be to develop partnerships with feed additive companies and explore the use of products as alternatives to growth-promoting antibiotics, said Shurson.
“[We] want to get to a point where we can use the growth promoting alternatives [to antibiotics] in a more predictable way to achieve the response that we want to achieve,” he said.
[This story has been updated with additional information.]