The results of Shlesha Ghimire's PhD research show that larger amounts of oats and barley can be used in broiler chicken feed without compromising growth performance or health.
The PhD project has provided a more detailed understanding of how broiler chickens are able to handle high-fiber grains such as barley and oats.
The hull of oats consists of insoluble fiber that is difficult for chickens to grind in the gizzard. The question has therefore been how the chickens' digestive system can cope with large amounts of this tough fiber.
Passes Through the Gizzard Without Being Ground
One theory of chicken digestion has been that all large fiber particles entering the gizzard remain there until they are finely ground before passing further through the digestive system, and that extensive use of a highly fibrous grain such as oats would limit feed intake in broiler chickens. However, Ghimire's research shows that once the gizzard reached its capacity, large fiber particles passed through without being ground.
The results showed that high levels of oat hulls in broiler feed did not reduce weight gain. The coarse particles stimulated increased gizzard development, while the fine particles improved feed efficiency and increased feed intake.
Meal Feeding Improves Nutrient Uptake
Another type of fiber, found in both oats and especially barley, has the property of dissolving in water and forming a thick, viscous liquid with high viscosity. This interferes with nutrient absorption in the digestive tract, preventing nutrients from being efficiently absorbed into the chicken's body. To reduce this problem, the enzyme NSPase is commonly added to feed.
The enzyme becomes active as soon as the chicken consumes the feed, and as it moves through the digestive tract, it breaks down the fiber. The challenge, however, is that feed passes through the digestive system so quickly that the enzyme does not have sufficient time to achieve optimal fiber degradation.
When broilers have free access to feed, they eat about every half hour and consume only small amounts at a time. However, if chickens are instead fed meals at specific times, they learn to eat more when feed is available, thereby filling the crop. This gives the enzymes more time to act, resulting in improved breakdown of soluble fibers. The chickens do not go hungry because they have food stored in the crop, which serves as a natural reservoir.
Making Better Use of High-Fiber Feed Ingredients with Limited Alternative Value
Sustainability and cost-efficiency are becoming increasingly important in livestock production. Ghimire's research has focused on the challenge of utilizing high-fiber feed ingredients that have limited alternative uses. She demonstrated that optimal fiber inclusion levels, particle sizes, and enzyme supplementation, combined with effective feeding strategies, improve nutrient digestibility and gut health, and can lead to lower feed costs and better growth performance.
On May 25, 2025, Shlesha Ghimire defended her doctoral thesis at the Norwegian University of Life Sciences (NMBU), entitled "Function and Fate of Fibre from Oats and Barley in diets for Broilers". Her principal supervisor was Professor Birger Svihus (NMBU). Co-supervisors were Professor Sebastian Kaczmarek (Poznań University) and Dr. Adam Smith (DSM).