They have different stomachs and digestive strategies. Chickens grind feed in a powerful gizzard, while pigs rely on enzymes and longer digestion times. Yet the PhD research of Lucas Schmidt Bassi shows that chickens and pigs utilize starch almost equally efficiently.
In his studies, Bassi found little support for the hypothesis that chickens and pigs have markedly different capacities for starch digestion. Both species demonstrated high and nearly complete starch digestibility.
Grain type matters more than animal species
In Bassi's experiments, broiler chickens and pigs were fed identical diets based on maize, barley, or oats. The results showed that grain type had a greater influence than animal species. Oats provided the highest starch availability in both species, followed by maize and barley.
These findings suggest that the properties of the starch itself and the structural characteristics of the grain are more important than the animal consuming the feed.
Chickens rely on mechanical breakdown
In broiler chickens, the upper digestive tract plays a central role. The gizzard functions as a powerful grinder that reduces feed particles in size. The experiments showed that chickens had considerably more small feed particles in the duodenum than pigs.
At the same time, the pH in the gizzard was substantially lower than in the pig's stomach. This creates favorable conditions for nutrient breakdown before the feed reaches the small intestine.
The intensive grinding process makes starch more accessible to digestive enzymes, allowing it to be broken down and absorbed rapidly. The study therefore showed that chickens digested starch more quickly in the proximal small intestine than pigs.
Pigs rely on enzymes
In pigs, digestion follows a different principle. Rather than depending on extensive mechanical grinding, pigs possess a highly developed enzymatic digestive system. The experiments revealed high activity of both lipase and amylase, and indicated that salivary amylase may initiate starch breakdown even before feed reaches the stomach.
Pigs also have a long digestive tract. Feed moves gradually through the system via rhythmic muscular contractions, giving enzymes ample time to break down nutrients.
The experiments further showed that pigs were less sensitive than chickens to changes in feed viscosity, or how thick the digesta becomes during digestion.
Similar transit rates, different traffic patterns
Bassi also investigated how quickly feed passes through the digestive system.
Here, the researchers found another surprising result. Despite major anatomical differences, chickens and pigs exhibited relatively similar passage rates through the upper digestive tract. However, the movement patterns differed.
In pigs, digesta moved steadily and continuously through the system. In chickens, movement was more pulsatile.
The researchers believe this may partly be explained by the fact that chickens store more feed in the upper digestive tract and exhibit antiperistaltic movements, which increase retention time. In other words, muscular contractions periodically reverse direction and move material backward.
Amylase was most effective in maize-based diets
Another part of the PhD research examined whether supplementation with the enzyme amylase could improve starch digestion in broiler chickens.
In maize-based diets, amylase resulted in more consistent starch digestion between individual birds. Variation among animals declined, which may contribute to a more predictable energy supply.
In barley-based diets, the effect was far weaker. When feed already contained enzymes targeting fiber components, adding amylase provided few additional benefits.
The results therefore show that the effect of enzyme supplementation depends on both grain type and the overall composition of the diet.
Important knowledge for future livestock production
Feed accounts for a large share of livestock production costs. More efficient utilization of starch can therefore have significant economic and environmental benefits. When animals obtain more energy from the same amount of feed, nutrient losses can be reduced while resources are used more efficiently.
Bassi's PhD demonstrates that chickens and pigs do not necessarily need the same digestive strategies to achieve similar outcomes. The findings provide new insight into fundamental digestive physiology and may contribute to more precise feed formulation and more sustainable livestock production in the future.
Lucas Schmidt Bassi, 33, from Brazil, will defend his PhD thesis “Phytochemical supplementation in diets for monogastric animals. Possibilities and challenges regarding nutrition and gut health” on 16 September 2026 at NMBU.
His principal supervisors were Professor Birger Svihus (NMBU) and Associate Professor Sebastian Kaczmarek (Poznań University). Co-supervisor was Dr Aron Cowieson of DSM Nutritional Products.