ABSTRACT The effect of using natural growth promoters (NGP) to replace traditional antimicrobials on performance, biometry of digestive and reproductive organs, sexual maturity and bone characteristics of replacement pullets was evaluated; and the relationship between these variables according to the diets was verified. Eight-week-old birds were randomly assigned to a completely randomized design and fed different diets: negative control (without growth promoters); positive control - conventional growth promoter; organic acids (OA); symbiotic (S); essential oil (EO); OA + S; and EO + S. The performance, relative weight of digestive and reproductive organs and length intestines, height and crest length, sternum length, bone quality and sexual maturity of birds were similar (p>0.05) between treatments. The heat map combined with cluster analysis showed a uniform static pattern with the formation of three horizontal groups formed by the treatments: 1) negative control, S and OA + S; 2) positive control and OE and 3) OA and OE + S. A null relationship between the treatments and the variables under study was observed. The principal components analysis revealed an association of variables in three components with 60.55% of variation. NGP can replace traditional promoters, as they do not interfere with performance, biometrics or sexual maturity. Height and length are predictive variables for the development of reproductive organs, especially the oviduct. A similarity was identified through multivariate techniques between symbiotic and organic + symbiotic acids; positive control and essential oils; and organic and symbiotic acids + essential oils.

ABSTRACT Two experiments were carried out with the objective of evaluating the effect of superdosing of two phytases on performance, egg quality, digestive organ biometry and bone quality of light hens in the first (58 weeks) and second (87 weeks) productive cycle. In the first cycle, 270 light hens were used, in which a completely randomized design was adopted in a 2 x 2 + 1 factorial scheme (bacterial phytase or fungal phytase x 450 FTUs or 900 FTUs + control diet). In the second cycle, 270 hens were used, following the same design as the previous experiment. The performance and quality of the eggs were evaluated in both cycles, and the biometry of the digestive organs and bone characteristics were also evaluated in the first experiment. There was no effect in the comparison between the means for the performance and egg quality (in both experiments), or for the biometric variables and bone characteristics (first experiment). There was no significant interaction between the factors for any of the variables in the two experiments. In the first experiment, egg production was higher with bacterial phytase and egg weight with fungal phytase. The mineral matter showed greater value with 450 FTUs. It is recommended to use bacterial phytase produced from Escherichia coli as it improves the performance of light laying hens. The dosage of 450 FTUs improves the mineral content of light laying hens and the use of phytase in the laying hen diet implies a lower feed cost.

ABSTRACT The aim of this study was to evaluate the effect of two types of phytases (the 1st produced from Escherichia coli and the 2nd from Aspergillus oryzae) with different dosages (300 and 900 Unit Phytase or FTU) on performance, organ biometry and bone quality of replacement pullets in the period of 8 to 17 weeks of age. A total of 288 Hy-Line White laying hens were used at 8 weeks of age. A completely randomized design was adopted in a 2 x 2 factorial scheme, totaling 4 treatments with 8 replicates of 9 birds each. Performance, biometric variables and bone characteristics were evaluated. There was no significant interaction between the factors for any of the evaluated variables. The conversion and the accumulated consumption were influenced (p<0.05) by the phytase dosages, with the highest results being observed for the consumption obtained with 300 FTU, and the best results for the feed conversion obtained with the dosage of 900 FTU. The relative weight of the liver was influenced by the treatments (p<0.05), presenting higher values with bacterial phytase and a dosage of 900 FTU. The sternum length and tibial deformity were influenced by fungal phytase (p<0.05). It is concluded that the use of 900 FTU superdosing and fungal phytase improves the performance and bone characteristics of light replacement pullets.

ABSTRACT Dietary inclusion of lipid sources has been one of the methods adopted by nutritionists aiming at better energy balancing. However, alternative energy feedstuffs have been sought in an attempt to reduce production costs. In this regard, lipid sources that can replace conventional ones, such as beef tallow, cottonseed oil, and sunflower oil have been investigated. The objective of this study was to examine the effects of different lipid sources on the performance, egg quality, biometrics of digestive organs, and bone quality of white-egg commercial layers in the first production cycle. A total of 216 Hy-Line White layers at 70 weeks of age, weighing 1.701 ± 0.103 kg, were used in a completely randomized design with four treatments and six replicates. The diets provided to them contained equal amounts of protein, calories, and amino acids, with only the lipid source varying - soybean oil (control), cottonseed oil, beef tallow, and sunflower oil. No significant effect of lipid sources was observed on any of the performance or egg-quality variables assessed (p>0.05). Biometric variables were not influenced by lipid sources, except for abdominal fat, which was highest in the birds receiving the beef-tallow treatments and lowest in birds fed the sunflower-oil diets (p<0.05). Except for mineral matter, bone traits were not influenced by the treatments; this variable was highest in the control treatments and lowest in the beef-tallow treatments. In conclusion, cottonseed and sunflower oils can be used to fully replace soybean oil in diets for white-egg commercial layers.