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This study was conducted to evaluate the effect of two levels of vitamin D 3 with or without 1,25dihydroxycholecalciferol (1,25(OH) 2 D 3) on live performance and bone quality of broiler chickens. For that, we used a completely randomized design in a 2 × 2 factorial arrangement, with eight replicates of 30 Cobb ® 500 male broiler chicks each (n = 960). The two levels of vitamin D 3 and the addition or not of 0.5 µg 1,25(OH) 2 D 3 /kg were considered as main factors. The vitamin D 3 levels were: 2500/2000 IU/kg and 1250/1000 IU/kg for the starter (1 to 21 days) and grower (22 to 40 days) phases, respectively, with the first representing the levels used in industry (100%) and the second, a reduction in 50% of those levels. The 1,25(OH) 2 D 3 source was Solanum glaucophyllum. On days 21 and 40, one broiler per replicate was killed and long bones were removed for analyses of mineral percentage, bone mineral density, biomechanical properties, and morphology. No significant differences were found related to vitamin D 3 levels and the addition or not of 1,25(OH) 2 D 3 for live performance, mineral percentage, strength, stiffness, and morphology. Toughness was lower when 1,25(OH) 2 D 3 was used at 21 days, but this effect was not observed at 40 days of age. Bone mineral density was greater when 100% of vitamin D 3 was used at 40 days of age. The reduction of up to 50% of vitamin D 3 levels is sufficient to ensure performance and bone development of broilers at 21 and 40 days of age. The inclusion of 0.5 µg 1,25(OH) 2 D 3 /kg in addition to diets with sufficient levels of vitamin D 3 shows no effect on the improvement of those parameters at the same ages.

This work aimed at evaluating the effects of 4 digestible Met+Cys levels on the diet of commercial layers and their influence on the productive performance, quality, and amino acid profile of eggs and economic viability of the activity. A total of 576 white Lohmann LSL-Lite layers was distributed into 6 replicates of 24 birds for each diet. The experimental design was completely randomized, with 4 treatments defined by levels evaluated in the feed (0.465, 0.540, 0.581, and 0.647%). The productive performance was measured for 30 weeks. The quality (34 and 50 wk old) and the amino acid profile of eggs (43 wk old) also were evaluated. A linear positive response was observed at higher Met+Cys levels for feed intake, number of eggs per housed bird, and digestible Met+Cys intake. Egg production, egg weight, egg mass, feed efficiency, and weight gain had their optimal values determined by the quadratic regression model at 0.638, 0.654, 0.647, 0.644, and 0.613% digestible Met+Cys, respectively. In the 34th wk, eggshell thickness decreased linearly at higher Met+Cys levels. In the 50th week, the optimal levels detected for eggshell thickness and percentage were 0.571 and 0.570% digestible Met+Cys, respectively. The percentages of proteins, branched-chain amino acids (leucine, isoleucine, and valine), histidine, and proline in eggs (albumen+yolk) showed a linear negative response in function of higher Met+Cys levels. Higher digestible Met+Cys levels (>0.630%) led to a good performance of layers, while lower Met+Cys levels improved the eggshell quality of layers in peak production. Optimal Met+Cys levels may change according to the price of the synthetic amino acid.

RESUMOAvaliou-se a influência da classificação dos ovos no incubatório sobre a uniformidade, o desempenho e o rendimento de abate dos frangos de corte, utilizando-se 140 machos e 140 fêmeas nascidos de cada um dos seguintes tratamentos: A -ovos com pesos entre 66 e 72g, 33,3% deles originados de matrizes com diferentes idades; B -ovos com pesos entre 58 e 65g, 33,3% deles originados de matrizes com diferentes idades; C -ovos com pesos entre 52 e 57g, 33,3% deles originados de matrizes com diferentes idades; D -ovos com pesos entre 52 e 72g, produzidos por matrizes com 31 semanas; E -ovos com pesos entre 52 e 72g, produzidos por matrizes com 38 semanas; e F -ovos com pesos entre 52 e 72g, produzidos por matrizes com 43 semanas. O delineamento experimental foi inteiramente ao acaso, em esquema fatorial 6 x 2 (seis categorias de peso dos ovos x dois sexos), com quatro repetições