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Pelleting is an energy-demanding process that is carried out on many animal feeds to assure a large macro-structure and thus improved handling properties and a high and homogenous feed intake. Due to the heat applied during conditioning and pelleting, some chemical alterations may take place. Proteins are to some extent denatured, and this will potentially improve nutritional value through inactivation of proteinous antinutrients, although may contribute negatively through inactivation of exogenous enzymes. Only a small fraction of the starch will be gelatinised, and pelleting will not affect starch digestibility to any considerable extent. Some vitamins, however, may be destroyed during the pelleting process, and viscosity of soluble fibres may increase.

Zimonja, O., Stevnebø, A. and Svihus, B. 2007. Nutritional value of diets for broiler chickens as affected by fat source, amylose level and diet processing. Can. J. Anim. Sci. 87: 553-562. Two experiments were conducted to investigate effects of fat source, fat level, amylose level and processing technique on technical pellet quality and broiler performance. In both experiments wheat-barley-based diets were either pelleted or expanded and pelleted using the same production conditions. In exp. 1 soy oil and akofeed fat at inclusion levels of 25 and 50 g kg -1 , respectively, were tested. Akofeed fat containing diets resulted in significant (P < 0.001) improvement in pellet durability compared with soy oil containing diets under both processing methods and both fat levels. As a consequence of higher content of amylose-lipid complexes, feeding the akofeed fat containing diets resulted in significant reduction (P < 0.05) of starch digestibility at jejunual level. In exp. 2, three barley cultivars with varying amylose content were tested. Total tract starch digestibility was higher (P < 0.0001) for normal amylose (NA) containing diets compared with low amylose (LA) and high amylose (HA) containing diets. In vitro results, however, showed highest starch degradation for LA diets compared with NA and HA diets, indicating that the in vitro method did not seem to be a good predictor of starch digestibility for broiler chickens. Les auteurs ont effectué deux expériences afin d'établir quels effets la source et la quantité de matière grasse, la concentration d'amylose et le procédé de transformation peuvent avoir sur la qualité technique des agglomérés et le rendement des poulets de chair. Pour les deux expériences, ils ont préparé une ration de blé et d'orge par agglomération ou expansion puis agglomération dans des conditions de fabrication identiques. Lors de la première expérience, ils ont inclus respectivement 25 et 50 g par kg d'huile de soja et de gras AkoFeed à la ration. La ration contenant du gras AkoFeed donne des agglomérés sensiblement plus durables (P < 0,001) que celle contenant de l'huile de soja pour les deux procédés de fabrication et les deux concentrations. La plus forte teneur en complexes amylose-lipides dans les rations à base de gras AkoFeed entraîne une baisse significative (P < 0,05) de la digestibilité de l'amidon dans le jéjunum. Pour la deuxième expérience, les auteurs ont testé trois cultivars d'orge à teneur variable en amylose. Les rations renfermant une concentration normale d'amylose (NA) se caractérisent par une meilleure digestibilité de l'amidon (P < 0,0001) dans le tractus gastro-intestinal que celles contenant peu (LA) ou beaucoup d'amylose (HA). Les essais in vitro révèlent néanmoins que l'amidon des rations LA se dégrade mieux que celui des rations NA et HA, signe que l'analyse in vitro ne permet pas de prévoir correctement la digestibilité de l'amidon chez les poulets de chair.Mots clés: Amidon, orge, complexe amylose-lipide; gras AkoFeed, huile de soja, expansion-agglomération Cere...

. 2008. Effects of fibre content in pelleted wheat and oat diets on technical pellet quality and nutritional value for broiler chickens. Can. J. Anim. Sci. 88: 613Á622. Two experiments were conducted to study the effects of either soluble or insoluble fibre naturally occurring in wheat and oats, on technical pellet quality and nutritional value for broiler chickens. In exp. 1, the effects of insoluble fibre were studied by mixing diets based on wheat or naked oats with either coarse or fine oats hulls followed by pelleting. Hull inclusion increased (PB0.05) starch gelatinisation, especially in the diets based on oats. Addition of finely ground oats hulls improved pellet durability, in particular after storage, while no such effect was observed for coarse oats hulls. Oats hulls inclusion caused a more elastic pellet with higher breaking resistance (PB0.05). Lower (PB0.05) energy consumption was observed for diets based on oats compared with wheat, while no effect of fibre inclusion on energy consumption was found. In exp. 2, the influence of pelleting on the viscosity effect of soluble fibres in diets based on wheat or oats was studied. A significant increase (P B0.05) in intestinal viscosity of broiler chickens was observed for all batches of grain exposed to steam pelleting. Viscosity was doubled (PB0.05) with wheat diets, while the increase in viscosity was even greater in oat diets. In wheat diets, feed intake and weight gain was reduced (PB0.05), while feed conversion ratio was not affected. Steam pelleting of oats reduced (PB0.05) feed intake and weight gain, and increased feed conversion ratio (PB0.05). The improvements (PB0.05) in metabolisable energy and dry matter digestibility in wheat diets was not consistent with the observed increases in viscosity or with the results obtained with oats.