Natural Growth Promoters Replacing Traditional Growth Promoters in Diets for Light Replacement Pullets: A Systematic Approach

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.(AU)

Different Calcium Levels and Two Limestone Granulometries in the Diet of Laying Hens: Performance and Bone Characteristics

The effect of different calcium levels and two limestone granulometries on performance, egg quality, biometry of digestive organs and bone characteristics of light laying hens were evaluated. A total of 270 laying hens were used during 112 days, distributed in a completely randomized design in a 3 x 2 factorial scheme, with 3 levels of calcium (3.8, 4.0 and 4.2%) and 2 limestone granulometries (0.222 and 1.922 mm), totaling 6 treatments with 5 repetitions each. The parameters evaluated were: feed intake, egg production, egg weight and mass, feed conversion per mass and per dozen eggs, albumen, yolk and shell percentage, specific gravity of eggs and shell thickness. In addition, the relative weight of the heart, proventricle, gizzard, liver, pancreas, intestine weight and length, and bone characteristics were also evaluated. A significant interaction was observed for tibia mineral matter. Egg production was influenced by the limestone granulometry, presenting greater value in the treatments which contained fine granulometry limestone. Higher calcium levels of 4.0 and 4.2% provide greater specific density of eggs. Biometric variables and bone characteristics were not influenced by the treatments. In conclusion, it is recommended to use fine-grained limestone (0.222 mm) and a 4% calcium level in diets for light commercial hens, as they improve performance and quality of eggs, without interfering in biometrics of digestive organs and bone characteristics.(AU)

Chelated Minerals and Limestone Particle Sizes on Performance and Bone Quality of Brown-Egg Layers

This study aimed to evaluate productive performance, egg quality, and bone quality of commercial brown-egg layers fed diets containing organic and inorganic minerals and three limestone particle sizes. A total of 288 birds at 64 weeks of age were distributed in a completely randomized design in a 2 × 3 factorial arrangement (two mineral sources and three limestone particle sizes) and eight replicates. The experiment lasted 112 days, divided into four periods. The following treatments were tested: T1 = inorganic minerals + 100% fine limestone; T2 = inorganic minerals + 50% fine limestone + 50% coarse limestone; T3 = inorganic minerals + 100% coarse limestone; T4 = inorganic + organic minerals + 100% fine limestone; T5 = inorganic + organic minerals + 50% fine limestone + 50% coarse limestone; and T6 = inorganic + organic minerals +100% coarse limestone. There was no significant interaction effect between the studied factors on any of the variables. No significant effect of the types of mineral mixes or limestone particle sizes were observed on the performance, egg quality, or bone quality variables evaluated. In conclusion, organic or inorganic minerals associated with limestone in fine, medium, or coarse particle sizes can be used in diets for brown-egg layers without affecting their productive performance, egg quality, or bone quality.(AU)

Chelated Minerals and Limestone Particle Sizes on Performance and Bone Quality of Brown-Egg Layers

This study aimed to evaluate productive performance, egg quality, and bone quality of commercial brown-egg layers fed diets containing organic and inorganic minerals and three limestone particle sizes. A total of 288 birds at 64 weeks of age were distributed in a completely randomized design in a 2 × 3 factorial arrangement (two mineral sources and three limestone particle sizes) and eight replicates. The experiment lasted 112 days, divided into four periods. The following treatments were tested: T1 = inorganic minerals + 100% fine limestone; T2 = inorganic minerals + 50% fine limestone + 50% coarse limestone; T3 = inorganic minerals + 100% coarse limestone; T4 = inorganic + organic minerals + 100% fine limestone; T5 = inorganic + organic minerals + 50% fine limestone + 50% coarse limestone; and T6 = inorganic + organic minerals +100% coarse limestone. There was no significant interaction effect between the studied factors on any of the variables. No significant effect of the types of mineral mixes or limestone particle sizes were observed on the performance, egg quality, or bone quality variables evaluated. In conclusion, organic or inorganic minerals associated with limestone in fine, medium, or coarse particle sizes can be used in diets for brown-egg layers without affecting their productive performance, egg quality, or bone quality.