ABSTRACT We evaluated the effect of adding proteases in diets of laying hens at peak production on the performance, egg quality, relative weight of digestive organs, and intestinal morphometry. Hy-Line W36 layer hens (390; 28-39 weeks old) were distributed in five treatments, with 13 animals each, with six replicates. The treatments were: control (standard formulation without nutritional reduction or protease inclusion), negative control A - NCA (nutritional reduction according to protease A matrix, without protease), negative control B - NCB (nutritional reduction according to protease B matrix, without protease), NCA + protease A, and NCB + protease B. The experimental period lasted 12 weeks, divided into three cycles of 28 days. Hens subjected to treatments (NCA and NCB) showed a decrease in feed intake. However, the addition of proteases A and B promoted improvement in this trait. The diets NCA and NCB had a negative influence on the production rate of the hens, but the diet supplementation with protease B resulted in significant improvement on egg laying rate. Hens subjected to nutritional reduction presented the worst results regarding mass and conversion by egg mass. However, the addition of enzymes reversed these results. Although the diets did not affect the relative weights of yolk, albumen, eggshell, Haugh unit, and specific gravity of the eggs, a higher eggshell thickness was observed in hens that received NCA, NCB, and NCB + protease B diets. The diets did not influence the relative weights of digestive organs and the small intestine morphometry. Hens fed diets supplemented with A and B have performance recovered in relation to those that received diets with reduced levels of nutrients.

Um experimento foi conduzido com o objetivo de estudar os efeitos dos níveis de cálcio nas rações sobre o desempenho e a qualidade de ovos de poedeiras comerciais. Foram utilizadas 216 poedeiras da linhagem Lohmann Brown no período de 39 a 55 semanas de idade. O delineamento utilizado foi inteiramente casualizado, composto de seis níveis de cálcio (3,0; 3,4; 3,8; 4,2; 4,6; 5,0%) e seis repetições de seis aves por parcela. Os níveis de cálcio avaliados não influenciaram os parâmetros produtivos, mas afetaram significativamente as porcentagens de albúmen e casca do ovo. O aumento do cálcio na dieta promove incremento na qualidade da casca do ovo em relação aos demais componentes do ovo. Recomenda-se nível de 4,3% de cálcio em dietas para poedeiras semipesadas após o pico de postura.

Two hundred and sixteen layers were raised from 39 to 55 weeks of age to study the effects of levels of calcium in the rations on performance and eggs quality of brown commercial layers. A completely randomized experimental design were used with six levels of calcium (3.0; 3.4; 3.8; 4.2; 4.6 and 5.0%) and six replicates of six layers hens. There was no effect of calcium levels on hen performance, however significantly affected the percentage of albumen and egg shell. The increase of calcium in the diet promoted increment in egg shell quality in relationship to other eggs components. The calcium level of 4.3% is recommended for brown layer hens after production peak.

Objetivou-se neste experimento avaliar o desempenho de poedeiras comerciais de 1 a 18 semanas de idade submetidas a níveis de Proteína Bruta (PB) e de Energia Metabolizável (EM). O experimento foi desenvolvido no aviário de Departamento de Zootecnia do Centro de Ciências Agrárias da UFPB, em Areia-PB. Foram utilizadas 432 pintainhas Lohmann Brown de três dias de idade, distribuídas em um delineamento inteiramente casualizado, em esquema Fatorial 3x3, com três níveis de PB e três níveis de EM. Na primeira fase, de 1 a 6 semanas de idade, as aves foram alimentadas com rações contendo três níveis de PB (21, 22 e 23%) e três de EM (2900, 3000 e 3100kcal/kg de ração). Na segunda e terceira fases, as aves com idades de 7 a 12 e de 13 a 18 semanas, respectivamente, foram alimentadas com três níveis de PB sendo 18, 19 e 20% de sete a doze semanas e 16, 17 e 18% de treze a dezoito semanas e três níveis de EM sendo 2700, 2800 e 2900kcal/kg de ração nessas duas fases. Não foi encontrada interação entre os níveis de PB e de EM. Com base nos resultados obtidos, recomenda-se, respectivamente, para as fases de 1 a 6, de 7 a 12 e de 13 a 18 semanas de idade, os níveis de 21% de PB e 2900 kcal de EM/kg de ração, 20% de PB e 2700 kcal de EM/kg de ração e 16% de PB e 2700 kcal de EM/kg de ração.

The aim of this experiment was to evaluate the performance of commercial layers between 1 and 18 weeks of age submitted to different crude protein (CP) and metabolizable energy (ME) levels. The trial was carried out at the poultry sector of the Department of Animal Science, of the Centro de Ciências Agrárias, Universidade Federal of Paraiba, Areia-PB, Brazil. Four hundred and thirty-two Lohmann Brown chicks were used at 3 days of age according to a completely randomized design in a 3 x 3 factorial scheme, with three CP levels and three ME levels. In the first phase (1-6 wk), the birds were fed with diets containing three levels of CP: 21, 22 or 23% CP and three levels of ME: 2,900, 3,000 and 3,100 kcal/kg diet. In the second phase (7-12 wk) and in the third phases (13-18 wk), CP levels of feeding were 18, 19 or 20%, and 16, 17 or 18%, respectively, and three ME levels being 2,700, 2,800 or 2,900 kcal ME/kg diet in these two phases. It was not found interaction between CP and ME levels. Based on the results obtained one recommends for the phases from 1 to 6, 7 to 12 and 13 to 18 weeks of age the levels of 21 % of CP and 2900 kcal of ME /kg diets, 20% of CP and 2700 kcal of ME/kg diets and 16% of CP and 2700 kcal of ME/kg diets respectively.