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Influence of feed form and particle size on performance, nutrient utilisation, and gastrointestinal tract development and morphometry in broiler starters fed maize-based diets

Published on: 10/6/2021
Author/s : S. Naderinejad 1, F. Zaefarian 2, M.R. Abdollahi 2, A. Hassanabadi 3, H. Kermanshahi 3, V. Ravindran 2 / 1 Department of Animal Science, Ferdowsi University of Mashhad, International Branch, Mashhad, Iran; 2 Monogastric Research Centre, Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Palmerston North 4442, New Zealand; 3 Department of Animal Science, Ferdowsi University of Mashhad, Mashhad, Iran.


  • Feeding pelleted diets, regardless of particle size, outperforms mash diets.
  • In pelleted maize diets, coarse particles do not depress the growth performance.
  • In pelleted maize diets, medium and coarse grinding reduces the gizzard pH.
  • Coarse maize particles enhance nutrient utilisation and maintain pellet quality.



The influence of feed form and particle size on the performance, coefficient of apparent ileal digestibility (CAID) of nutrients, apparent metabolisable energy (AME) and intestinal morphology in broiler starters fed maize-based diets was examined in this study. Two feed forms (mash and pellet) and three particle sizes (fine, medium and coarse) were evaluated in a 2 × 3 factorial arrangement of treatments. Birds fed pelleted diets had higher (P < 0.05) weight gain and feed intake than those fed mash diets. In mash diets, fine grinding resulted in lower (P < 0.05) feed per unit gain compared to medium and coarse grinding, whereas, in pelleted diets, there was no effect (P > 0.05) of particle size. Gizzard pH was not influenced (P > 0.05) by particle size in mash diets, but fine grinding increased (P < 0.05) gizzard pH compared to medium and coarse grinding in pelleted diets. Pelleting reduced (P < 0.05) the CAID of nitrogen but increased (P < 0.05) the ileal fat digestibility. Particle size had no effect (P > 0.05) on CAID of starch and AME in mash diets, but in pelleted diets, pellets made from medium and coarsely ground maize showed higher (P < 0.05) starch digestibility. Coarse grinding resulted in higher (P < 0.05) AME in pelleted diets. Feeding pelleted diets reduced (P < 0.05) the CAID of calcium and phosphorus, but increased (P < 0.05) that of sodium. Medium and coarse grindings resulted in higher (P < 0.05) calcium digestibility than fine grinding. Feeding pelleted diets reduced (P < 0.05 to 0.001) the relative length of all small intestinal segments and the relative weight of pancreas, proventriculus, and gizzard. Medium and coarse grinding increased (P < 0.05) the gizzard weight compared to fine grinding. In both the duodenum and jejunum, birds fed pelleted diets had greater (P < 0.05) villus height than those fed mash diets. Goblet cell number in duodenum was higher (P < 0.05) in birds fed diets containing fine particles compared to those fed medium and coarse particle sizes. The crypt depth in jejunum was greater (P < 0.05) in birds fed pelleted diets. Overall, the present data showed that coarse grinding of maize, through enhanced gizzard development and functionality, is beneficial to nutrient and energy utilisation and growth performance in broilers fed pelleted diets.


Key words: Feed form, Particle size, Broilers, Performance, Nutrient utilization.


Abstract published in Animal Feed Science and Technology, Volume 215, May 2016, Pages 92-104. https://doi.org/10.1016/j.anifeedsci.2016.02.012.

Author/s :
M. Reza Abdollahi is currently working as a Postdoctoral Research Fellow in Poultry Nutrition in Institute of Veterinary, Animal and Biomedical Sciences (IVABS), Massey University. Based on his doctoral research, Dr. Abdollahi has been awarded three prestigious awards. First, the award for best postgraduate oral presentation at the 2009 Australian Poultry Science Symposium, held in Sydney, Second, the 2010 Alltech (USA) Young Scientist Award at the Postgraduate level, and third, the award for Excellent Scientific Oral Presentation at the 15th AAAP Animal Science Congress, held in Bangkok, 2012
Ravi Ravindran graduated with a honours degree in Agricultural Science from University of Sri Lanka and subsequently Master of Science and PhD degrees in Animal Nutrition from Virginia Tech University.Prof. Ravindran is an acknowledged world leader in the areas of measurement of amino acid availability in poultry and feed enzymes, particularly microbial phytases. His work has addressed various aspects of feed evaluation, gut flora management, early nutrition and, digestion and metabolism of amino acids and minerals in poultry.
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