National industries that produce balanced feed for animals use high volumes of imported raw materials, which translates into high formulations costs. The importance of improving feeding practices in the poultry sector. Pelletizing is the most widely used thermal process in the poultry industry. Using pellet in broiler diets has advantages in improvements in the digestibility of starches due to chemical changes during this process. Improvements in BW, FC and FCR in broiler (Calet 1965, Douglas et al. 1990). The experiment was carried out in an experimental farm, 3150 one-day- old Cobb 500 mixed birds were used, weighted once a week. The treatments consisted of different percentages of fine particles (FP) in the feed, 0% FP, 15% FP and 30% FP. Different sizes of one-day-old chicks were used, small: with 30, medium 40 and large 55 weeks of age in breeders. Different results of zootechnical parameters such as accumulated body weight (BW), feed consumption (FC) and feed conversion (FCR) at 7, 21 and 35 days of age. Chick size has a significant effect (P <0.0001) on the BW of birds at 7 days of age. The large chicken presented greater BW than the medium and medium greater than the small one. At 21 days of age of the birds, were differences (P <0.0001) large-medium chick BW was greater than the small. No significant differences (P> 0.05) between the 3 levels of FP in the feed until 21 days, but at 35 days of age it has a difference. At 35 days of age, there are significant differences (P <0.0001). The highest BW obtained was the chickens that were fed with 0% FP. No differences were observed between the BW of chickens fed with 0% and 15% of FP, nor between those of 15% and 30% of FP. Significant difference (P = 0.014) was observed between FP levels of 0 and 30%. There were no differences between 0 and 15% of FP, nor between 15 and 30% of FP. According to the level of FP in the feed, the best conversion was the chicken that consumed feed with 0% FP. Initial weight of the bird had an effect during all the period.
Effect of the percentage of fine particles in the feed, 0% of fine particles in the feed obtained the best BW, FC and FCR. The highest carcass weights are observed in large and medium-sized chickens, and those with consumption of 0 and 15% FP.