The proportion of fine particles in pelleted diets does not affect performance of slow-growing broiler chicks

35 36 Background: Slow-growing chicken strains have particular nutritional and digestive needs, so 37 it is possible that they make use of pelleted feeds differently than do birds of commercial strains. 38 Objective: To evaluate the performance, feed digestibility, serum biochemical profile, 39 digestive morphometry, carcass and cut yields of slow-growing broiler chicks fed pellet feeds 40 containing different concentrations of fines. Methods: The animals were distributed in a 41 completely randomized design with a 2 x 3 factorial scheme (Sex: male or female; Feed 42 proportion of fine particles: 0, 50 or 100%), with six repetitions of five birds/cage. A total of 43 180 slow-growing broiler chicks (Isa Label strain) with age of one day were used. The birds 44 received water and were feed ad libitum during the 28-day experimental period. Results: The 45 proportion of fine particles did not affect the metabolic, digestive or productive variables 46 evaluated. The males showed a better overall performance, while the females produced better 47 thigh and liver yields. Conclusion: The proportion of fine particles in pelleted feeds did not 48 affect the productive or metabolic parameters, so improved quality of pelleted feed for slow49 growing broilers in the initial rearing phase is not economically justified. 50