Effect of whole wheat inclusion and pellet diameter on pellet quality and performance in broilers

Whole wheat (WW) is mainly fed to broilers along with a pelleted feed, which allows birds to select particles leading to inconsistent results. WW inclusion in a pellet may require larger pellets to maintain coarse structure and pellet quality. The effect of WW vs ground wheat (GW) inclusion and pellet diameter (4 vs 6 mm) on pellet quality and performance was investigated, using a 2x2 factorial design with 6 replicates per treatment (9 Ross 308 males per pen). An additional group was fed a reference diet (RD) containing GW in a 3 mm pellet diameter. From day 0-7, all birds received a crumble starter diet (250 g/kg GW). From day 8-14, one group received the RD and the other 4 groups a 4 mm pelleted diet, which included either GW or WW. From day 15-34, half of these 4 groups received the 6 mm pelleted diets (GW or WW). Formulations of all diets from day 8-34 were similar (350 g/kg wheat). Pellet durability, tested using a Ligno tester, was the highest in the RD (75.5%), tested with sieve size 2.1 mm. When tested with sieve size 3.6 mm, GW 6 mm had the highest durability (59.7%) and the lowest durabilities were found using both sieves in WW 6 mm diets (60.8% and 36.6% for 2.1 and 3.6 mm, respectively). Feed intake (FI) and feed conversion ratio (FCR) was higher for GW vs WW diets from day 8-14 (53.6 vs 51.1 g/d, P=0.032 and 1.314 vs 1.269, P=0.038, respectively). For RD the lowest FCR (1.240, P=0.031) and highest bodyweight gain (BWG) (44.0g, P=0.010) was found. From day 15-34, FI and BWG was also higher for GW vs WW diets (154.9 vs 148.6 g, P<0.001 and 107.8 vs 103.9 g, P<0.001, respectively). Furthermore, FCR was better for the 4 mm pellet compared to the 6 mm pellet (1.408 vs 1.425, P=0.014); RD showed the lowest FI (145.5 g/d, P<0.001) and BWG (102.7 g, P=0.011), FCR remained unaffected. Overall, these results showed that 4 and 6 mm pellets vs 3 mm improve FI and BWG and that WW in pellets (vs GW) reduces FI and BWG, but improves FCR.