Effects of Grinding Method, Particle Size and Physical Form of Diet on Digestion in Laying Hens

New research from Germany reveals that feeding a coarsely ground or mash diet stimulates the development of the gut organs, and that mash feeding increases glucose transport capacity through changes in the intestinal microstructure.
calendar icon 26 August 2014
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Several studies illustrated that the structure of feed, i.e., the particle size, particle-size distribution, and the physical form of the diet, affects the avian gastrointestinal function and health leading to changes in productive performance.

In the current issue of Poultry Science, Ilen Röhe of the Free University in Berlin and co-authors there and at the International Research Association of Feed Technology in Braunschweig report that investigations concerning the effects of feeding differently processed diets on laying hens are limited and primarily concentrated on bird performance.

Their study examines the effect of feed processing on the gastrointestinal morphology and on the jejunal glucose transport of laying hens.

In eight replicates, a total of 384 hens (Lohmann Brown) aged 20 weeks were randomly allocated to eight different groups and fed over a period of 21 days in a three-factorial design.

Diets differed in

  • grinding method, either hammer or roller mill
  • physical form, either mash or expandate, and
  • particle size, either coarsely or finely ground.

During the experimental trial, the laying performance of each feeding group was recorded daily and the feed intake and bodyweight determined weekly.

After slaughtering, the weights of the pancreas, proventriculus, gizzard and small intestine were measured. Villus lengths and crypt depths of the duodenum, jejunum, and ileum were determined.

The jejunal electrogenic glucose transport was studied in Ussing chambers.

Hens that received mash instead of expandate had a heavier proventriculus (P=0.011), gizzard (P<0.001) and pancreas (P=0.019), whereas the feeding of coarsely instead of finely ground diets led to higher gizzard weights (P<0.001).

Mash-fed hens showed longer duodenal (P<0.001) and shorter ileal villi (P=0.047) and increased duodenal villus height-to-crypt depth ratios (P<0.001) than those given the expandate.

Mash-fed hens had higher glucose transport rates than expandate-fed hens (P<0.001).

The feeding of coarsely ground and mash diets stimulated the development of the gastrointestinal organs, concluded Röhe and co-authors.

They added that mash feeding influenced the intestinal microstructure of the epithelium in a way that increased glucose transport capacity.


Röhe I., I. Ruhnke, F. Knorr, A. Mader, F. Goodarzi Boroojeni, R. Löwe and J. Zentek. 2014. Effects of grinding method, particle size, and physical form of the diet on gastrointestinal morphology and jejunal glucose transport in laying hens. Poultry Science. 93: 2060-2068. doi: 10.3382/ps.2013-03783.

Further Reading

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August 2014

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