NETHERLANDS— Presenting at the 2nd International Feed Technology Congress in Netherlands, Birger Svihus, professor of nutrition, Norwegian University of Life Sciences, said coarser micro and macrostructure broiler diets may boost bird performance.

There is an increasing focus on the structure of broiler diets today brought on by the need to lower the cost of feed production.

It has also been shown that too fine grinding of feed reduces the performance of broiler chickens, Feed Navigator quotes Svihus as saying. Adding that poultry diet structure affects both technical and nutritional properties.

“When we talk about the structure of the diets, we distinguish between the macrostructure, which is the size, the length, and the diameter of the pellets, along with the number of fines, and so forth, and that is determining feed intake.

On the other hand, we have the microstructure which is the distribution of the particles that the pellet comprises. This is important for simulating the digestive tract and gizzard development,” he said.

We are still in a process of finding out, of fine-tuning what the optimum macro and microstructure is, to optimize bird performance and keep them healthy. Though, he continued, a delicate interaction exists between macro and microstructure that complicates optimization.

Stimulation of gizzard development through coarse microstructure may boost bird performance through improved nutrient digestibility, longer gizzard retention time, smaller particles due to better grinding in the gizzard, lower gizzard pH, and better synchronization of feed flow into the intestine, he said.

Additionally, there will be fewer gut health problems due to, among other aspects, fewer undigested nutrients in the lower digestive tract. Moreover, according to Svihus, by increasing pellet diameter, studies indicate that pelleting capacity would increase and energy consumption would decrease.

For pelleted diets where no hull rich cereals are used, a final wet sieving particle distribution where up to 40% of the particles are larger than 1mm, and half are larger than 2mm would be ideal.

“This can be achieved by roller milling or hammer milling using larger holes in the screen, combined with using a rather large pellet diameter (4-5mm).”

Despite this coarse grinding and large pellet diameter, experiments carried out to date show no negative effects on pellet durability or broiler performance he said.

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