Influence of pellet length changes at 4, 5 and 6 weeks of age and two pellet diameters on growth performance and carcass characteristics of broiler finishers

Abstract

A 2 × 4 factorial arrangement of treatments was used to evaluate the effects of two pellet diameters and four pellet length–week combinations on the growth performance and carcass characteristics of broilers (days 22 to 42). A broiler finisher diet based on wheat and soybean meal was formulated. Pelleted diets were manufactured in four different sizes: (i) 3 mm diameter (D3) and 7 mm length (L7), (ii) D3, 9 mm length (L9), (iii) 4.76 mm diameter (D4.76), L7, (iv) D4.76, L9. The four pellet sizes were then used to develop eight feeding treatments: (i) D3 and L7 pellets during weeks 4, 5, and 6 (L777); (ii) D3 and L7 during weeks 4 and 5, and L9 during week 6 (L779); (iii) D3 and L7 during week 4, and L9 during weeks 5 and 6 (L799); (iv) D3 and L9 during weeks 4, 5, and 6 (L999); (v) D4.76 and L7 during weeks 4, 5 and 6 (L777); (vi) D4.76 and L7 during weeks 4 and 5, and L9 during week 6 (L779); (vii) D4.76 and L7 during week 4, and L9 during weeks 5 and 6 (L799); (viii) D4.76 and L9 during weeks 4, 5, and 6 (L999). Increasing the pellet length from 7 to 9 mm increased pellet hardness at both pellet diameters and improved the pellet durability index in D3 pellets but had no effect in D4.76 pellets. Over the whole trial period (days 22–42), birds fed D3 pellets were heavier and had lower feed per gain and higher carcass yield than those fed D4.76 pellets. Feeding length–week combination L999 resulted in lower carcass yield than L777, L779, and L799. Overall, it is concluded that whilst broiler finishers express a preference for a smaller pellet diameter, there is no negative effect of pellet length (up to 9 mm) on performance parameters even when offered as early as day 21.