Padronização da secagem e uso da levedura em rações para aves

Abstract

The objective of this study was to evaluate the chemical composition and energetic of the sugar cane yeast and subjected to different temperatures and drying times by rotative rolls, besides determining the optimum level of inclusion in the diet of layer hens and broilers. The research was conducted in four steps using a completely randomized delieamento and statistical analyzes using SISVAR program. The first step was conducted experiment in the distillery who performed the yeast drying by rotatives rolls, in order to determine the best temperature and drying time for sugar cane yeast, aiming at its better chemical composition. Treatments were arranged in a factorial 3 temperatures (95, 100 and 107ºC) x 3 drying times (93, 107 and 123 seconds), with five replicates. There was a significant interaction for all variables. The interaction for dry matter was linear increasing to 93', not significant for 107' and with point of minimum (99 º C) to 123 seconds; the highest values of the crude protein were obtained at 100, 99 and 101ºC, respectively, for the drying times of 93, 107 and 123 seconds; the gross energy was maximal in drying to 102°C for 93' and with 101°C for 123'; the lowest concentration of ether extract was obtained at a temperature of 101°C for 93 seconds; the mineral matter showed minimun point at temperatures of 102, 95 and 101ºC respectively for times of 93', 107' and 123 seconds. In the second step were selected the five yeasts that showed higher levels of CP in the previous experiment, aiming to determine their energy values for poultry. To this end, were conducted three trials metabolism, one with layers hens and two with broilers. For layer hens there were no differences in AME, AMEn and CAMGE between yeasts, with mean of 1773 kcal/kg 1733 kcal/kg and 40.22%, respectively, were observed though the CAMDM was higher for dry yeast to 100 º C for 93 seconds (50,36%). For the first trial with broilers, the AME (1633 Kcal / kg), AMEn (1382 Kcal / kg) and CAMGE (32.22%) were best for the temperature of 95°C for 107 seconds, but there was no significant difference in the values of CAMMD presenting mean of 29.63%. The other metabolism assay metabolism with broiler used the yeast that showed better results in the above trials with broilers and was conducted in pre-initial, initial, and growing of broilers and were found values of 2723 kcal/kg; 1604 kcal/kg and 1414 kcal/kg of AME; 2366 kcal/kg, 1391 kcal/kg and 1303 kcal/kg of AMEn; 52.43%, 36.74%, and 25.64% of CAMDM; and 54.37%, 33.49% and 24.96% of CAMGE, in the ages of 1 to 8 days, 14 to 22 days and 28 to 36 days, respectively. The step three of the experiment was conducted to evaluate the effect of the inclusion of sugar cane yeast in diets on the performance parameters, egg quality and intestinal histology of laying hens. 240 layer hens were distributed in five treatments and six replicates of 8 birds each. Treatments consisted of different levels of yeast: 0; 2.5; 5.0; 7.5 to 10.0%. The inclusion of yeast caused a positive linear effect on egg production, egg mass and yolk color; there was a linear reduction of the mass conversion of eggs and Haugh unit; quadratic effect, point of maximum and minimum level of 6.7% for the percentage of yolk and albumen, respectively; intestinal histology was not affected. The fourth step of the experiment was conducted to evaluate the effect of increasing levels of yeast in the diet on performance, carcass yield, organ development and histology of the intestinal mucosa of broilers from 1 to 42 days age. 450 male broilers chickens, Cobb 500, distributed in a completely randomized design consisting of five treatments and six replicates of 15 birds each. The treatments consisted of the following levels of sugar cane yeast: 0; 1.25; 2.5, 3.75 and 5.0%. No were found significant differences in performance parameters, except for the weight gain at 7 days of age that was higher in the 3.05% level of inclusion; the villi height, crypt depth and ratio villus:crypt linearly decreased with yeast levels, however, the level 1.25% was which provided greater heights of villi when compared to the reference treatment. At seven days only the yield of the pancreas was a linear increase, at 42 days the chilled carcass yields increased linearly with yeast levels and abdominal fat decreased quadratically to the level of 2.36%; the other variables of carcass yield and cuts suffered no influence of the presence of yeast. It is concluded that the drying the yeast at 100°C by 107 seconds provided better conditions for use in feed for laying hens and inclusion of 10% in the diets of laying hens; and for broilers a drying at 95°C by 107 seconds with inclusion to 5 % in the diets, however, for lower levels of abdominal fat in the carcass indicated is the maximum level of 2.36% inclusion.