This study aimed to estimate the energy requirements for maintenance and gain of Japanese and European quails under growth housed in two rearing systems: floor pens and cages. To determine maintenance requirements, two experiments were conducted with birds housed in cages in environmental chambers (experiment 1) and in floor pens at room temperature conditions (experiment 2). The experimental design was completely randomized with four levels of feed supply (100, 75, 50 and 25%) and four repetitions. Energy requirements for maintenance were estimated by the comparative slaughter method through a feeding trial. In experiment 1, 64 Japanese and European quails per treatment were housed in cages of climatic chambers at 18, 24, and 28 °C, while in experiment 2, 352 quails per treatment were housed in floor pens at room temperature (26 °C). To estimate gain requirements, five slaughters were performed with quails receiving feed ad libitum and housed under controlled temperature of 18 °C (experiment 3). Prediction equations were obtained to estimate requirements for maintenance and gain of energy for the two genotypes of quails. The room temperature and breeding system affected the estimates of energy requirements for maintenance. The genotypes presented different estimates for maintenance and gain. Prediction models should be developed considering the room temperature and quails' genotypes.

O experimento foi realizado para avaliar o efeito dos níveis de cálcio (Ca) e da granulometria do calcário (GC) para poedeiras comerciais. Foram utilizadas 216 poedeiras da linhagem Dekalb White de 25 a 49 semanas de idade em um delineamento inteiramente casualizado, em esquema fatorial 3 × 2, composto de três níveis de cálcio (3,92; 4,02 e 4,12%) e duas granulometrias do calcário (fina - 0,60 mm; e grossa - 1,00 mm), que resultaram em seis tratamentos, com seis repetições de seis aves. Não houve efeito significativo dos níveis de cálcio e da granulometria do calcário nem da interação nível de cálcio × granulometria do calcário para o consumo de ração, o peso dos ovos, a gravidade específica, a espessura da casca, a porcentagem de casca, a unidade Haugh, a digestibilidade de cálcio e fósforo e a porcentagem do trato digestório. A produção, massa, conversão por massa e conversão por dúzia de ovos tiveram seus melhores resultados com 4,12% de cálcio na dieta. A porcentagem de moela e o consumo de ração observado às 15 h melhoraram com o aumento na granulometria do calcário de 0,60 para 1,00 mm. Houve efeito da interação entre nível de cálcio e granulometria do calcário para a resistência à quebra da tíbia, a densidade óssea, o comprimento do intestino delgado e o consumo de ração às 6, 9, 12, 18 e 21 h, respectivamente. Recomenda-se a adição de 4,12% de cálcio e calcário na granulometria grossa (1,00 mm) para melhor desempenho de poedeiras comerciais. Mais estudos são necessários para elucidar os mecanismos envolvidos na alteração do comportamento alimentar das poedeiras em resposta às mudanças nos níveis de cálcio e na granulometria do calcário das rações.

This experiment was conducted to evaluate the effect of levels of calcium (Ca) and particle size of limestone (LS) for laying hens. It was used 216 Dekalb White laying hens at 25 to 49 weeks of age in a completely randomized design in a 3 × 2 factorial arrangement, composed of three levels of calcium (3.92, 4.02 and 4.12%) and two particle sizes of limestone (thin - 0.60 mm; and thick - 1.00 mm), resulting in 6 treatments with six replicates of six birds. There was no significant effect of levels of calcium and limestone particle size neither of the interaction calcium × particle size for feed intake, egg weight, specific gravity, shell thickness, shell percentage, Haugh unit, calcium and phosphorus digestibility and percentage of digestive tract. Production, mass, conversion by mass and conversion by egg dozen had their best results with 4.12% of calcium in the diet. Percentage of gizzard and feed intake observed at 3:00 p.m. improved as limestone granulometry improved from 0.60 to 1.00 mm. There was an interaction effect among calcium level and limestone granulometry for breaking strength of tibia, bone density, length of the small intestine and feed intake at 6:00 a.m.; 9:00 a.m., 12:00 p.m., 6:00 p.m. and 9:00 p.m., respectively. It is recommended the addition of 4.12% of calcium and limestone in the thick granulometry (1.00 mm) for a better performance of commercial laying hens. More studies are needed to elucidate the mechanisms involved in the alteration of nutritional behavior of laying hens in response to changes in the levels of calcium and in the granulometry of limestone in the rations.