Effect of grinding and pellet dimensions on performance, digestive tract functionality and feeding behavior of broiler chickens fed diets based on wheat and maize

Research has indicated that the size of the pellet can be increased beyond the current industrial practice of using 3-4 mm pellets, without negative effects on performance and with improvement in pelleting efficiency as a result. To further elucidate the capacity of broilers for large pellets, a coarse wheat- and maize-based diet ground using either a hammer mill or a roller mill was pelleted using either a 3 mm diameter die or a 5 mm diameter die, and were cut to a length of 6 mm. For the 5 mm diameter die, pellets with a length of 8 and 10 mm were also made. Feeder rate and conditioning temperature were varied to assure similar physical quality among diets. More coarse particles were preserved during pelleting when the die diameter was 5 mm. The diets were fed to male Ross 308 broiler chickens from 10 to 34 d of age. Neither increasing the diameter nor the length of the 5 mm pellets had any negative effect on weight gain between 10 and 16 or 17 and 34 d of age. A feed preference test showed that birds willingly ate particles larger than 4.8 mm even at 16 and 22 d of age. At 29 d of age, they strongly preferred these largest particles. In conclusion, broiler chickens can be given larger pellets than current industrial practice, potentially increasing pelleting capacity and reducing energy consumption, while simultaneously preserving more of the gizzard-stimulating coarse microstructure of the particles constituting the pellet.