Estimate of choline nutritional requirements for chicks from 1 to 21 days of age.

Choline is an essential nutrient in poultry diets because it performs various important metabolic functions. The objective of this study was to re-evaluate the choline requirements of male broiler chickens from 1 to 21 days of age at two levels of methionine. Two assays using 2,160 Cobb® chickens (1,080 in each assay) were conducted. The study design was completely randomized and consisted of six treatments and six replicates, with 30 animals per experimental unit. The semipurified basal diet was formulated with corn, soya bean meal, soya protein concentrate, starch and sugar, providing 390 mg/kg choline and 0.593% digestible methionine (requirement level) in Assay 1 and a reduction of about one-quarter in the requirement level of digestible methionine (0.440%) in Assay 2. Choline chloride (62.5%) was added by a supplementation technique to both basal diets to compose crescent levels of choline supplementation (715, 1,040, 1,365, 1,690 and 2,015 mg/kg). The weight gain responses were fitted using quadratic polynomial (QP) and broken-line (BL) models. The ideal intake of choline (mg/bird.day) was estimated from the first intercept of the QP with the BL plateau (BL + QP). The results showed that the diet with the 25% reduction in digestible methionine limited the maximum weight gain by approximately 10%. The choline requirements of broilers from 1 to 7, 1 to 14 and 1 to 21 days of age were 27,013, 44,458 and 62,535 mg/bird.day, respectively, for the requirement level of digestible methionine and 26,796, 41,820 and 56,578 mg/bird.day for the broilers receiving the diet with the 25% reduction in digestible methionine.

Replacing corn with sorghum in the diet alters intestinal microbiota without altering chicken performance.

Sorghum grain can be used to replace corn in broiler diets. However, the effects related to an abrupt change between these grains are not yet clear. The aim of this study was to evaluate the performance and intestinal health of broilers fed diets containing corn and/or sorghum during different periods of rearing. To accomplish this aim, 2100 male chicks were fed the following experimental diets: C100% (corn-based diet); S100% (sorghum-based diet); C:S50% (diet based on corn and sorghum 1:1); PC-S (corn-based diet in the pre-starter phase and sorghum-based diet in subsequent phases); and PS-C (sorghum-based diet in the pre-starter phase and corn-based diet in subsequent phases). The study was conducted with two simultaneous trials in a randomized block design as follows: a performance trial up to 40 days occurred in floor pens (n = 8), and the metabolism trial occurred in cages (n = 10). Performance, jejunal morphometry, number of goblet cells, apparent metabolizable energy (AME), apparent metabolizable energy corrected for nitrogen (AMEn) and the coefficient of apparent metabolizability of dry matter (CMDM) of the diets, and the intestinal microbiota of small intestine and caeca at 10 and 21 days of age (16S gene sequencing) were evaluated. The different experimental diets did not affect performance, jejunal epithelium, AME, AMEn or CMDM. However, the experimental diets altered the percentages of the genera Clostridium, Weissella, Bacillus and Alkaliphilus in the small intestine. In addition, the genera Lactobacillus and Desulfotomaculum in the caeca were altered. The age also affected the microbiota of the intestinal segments. In conclusion, feeding sorghum in place of corn as well as the grain change after the pre-starter phase does not alter broiler performance. However, sorghum alters the intestinal microbiota, resulting in a lower percentage of Clostridium and a higher percentage of Lactobacillus in the small intestine and caeca, respectively.

Eficiência de uma fitase bacteriana na liberação de fósforo fítico em dietas de frangos de corte / Efficiency of a bacterial phytase to release phytate phosphorus in broiler chicken diets

Foi avaliada a eficiência de uma fitase (FT) bacteriana na liberação de fósforo fítico utilizando-se curvas de calibração para características ósseas e de desempenho em frangos de corte. O delineamento experimental foi inteiramente ao acaso, com seis tratamentos e seis repetições até 28 dias de idade. O tratamento-controle foi uma dieta à base de milho e farelo de soja deficiente em fósforo (P). Dois tratamentos corresponderam às dietas basais acrescidas de P suplementar, 0,05 por cento e 0,10 por cento, e os outros à dieta basal com 66, 99 e 131 FTU/kg de ração. A curva padrão é definida pelo efeito da adição de P suplementar consumido sobre características ósseas e de desempenho, e os resultados dos tratamentos com fitase são confrontados com a curva para cálculo de P liberado. A adição de P suplementar influenciou o ganho de peso, o peso vivo e o consumo de ração de forma quadrática, bem como miligramas de cinzas ósseas de forma linear. A curva padrão adotada foi da variável miligramas de cinzas ósseas, pois a resposta linear melhor descreve a curva. As inclusões de 66, 99 e 131 FTU/kg liberaram, respectivamente, 0,048 por cento, 0,049 por cento e 0,062 por cento de P. A fitase bacteriana é eficiente na liberação de fósforo fítico e possui viabilidade econômica.

The objective was to determine the efficiency of a bacterial phytase to release phytate phosphorus using calibration curves for performance and bone characteristics in broiler chickens. A completely randomized design with 6 treatments and 6 replicates was used in an experiment with chickens from 1 to 28 days of age. The control treatment was a diet based on corn and soybean meal deficient in phosphorus. Two treatments consisted of the basal diet supplemented with additional phosphorus (0.05 percent and 0.10 percent), and the other treatments received 66, 99 and 131 FTU/kg of feed. The standard curves represented the effect of the levels of additional P intake on performance and bone variables. Then, the responses of the phytase treatments were compared to the standard curves to calculate the P released. The increasing levels of supplemental P had a quadratic effect on weight gain, live weight and feed intake, and linear effect on mg of bone ash. The standard curve elected was mg of bone ash because linear response better represents the curve. Inclusion of 66, 99 and 131 FTU/kg released 0.048 percent, 0.049 percent and 0.062 percent. The bacterial phytase is efficient in releasing phytate, which may be of economical significance.

Intestinal bacterial community and growth performance of chickens fed diets containing antibiotics.

This study was conducted to relate the performance of broiler chickens fed diets containing growth-promoting antibiotics to changes in the intestinal microbiota. The technique of denaturing gradient gel electrophoresis (DGGE) of amplicons of the region V3 of 16S rDNA was used to characterize the microbiota. Two experiments were conducted, one with broilers raised in battery cages and the other with broilers raised in floor pens. Antibiotics improved the performance of the chickens raised in floor pens only. Avilamycin, bacitracin methylene disalicylate, and enramycin induced changes in the composition of the intestinal bacterial community of the birds in both experiments. The number of bacterial genotypes found in the intestinal tract of chickens was not reduced by the antibiotics supplemented in either environment. However, the changes in the composition of the intestinal bacterial community induced by antibiotics may be related to improvement in growth performance. This was indicated by the suppression of 6 amplicons and the presence of 4 amplicons exclusive to the treatment that had the best performance in the floor pen experiment.