ABSTRACT
The use of a suitable methodology to quantify the phytate phosphorus (Pphy) content in both the feed and the excreta from broilers is required to enable accurate calculation of the catalytic efficiency of the phytase supplemented in the feed. This study was conducted to compare 2 analytical methodologies (colorimetry and also high-performance liquid chromatography with a refractive index detector) in order to calculate the phytase efficiency by utilizing the results from the methodology that was shown to be the most appropriate. One hundred and twenty broilers were distributed in a (4+1)×2 factorial arrangement, corresponding to 4 diets that were equally deficient in P supplemented with increasing levels of phytase (0, 750, 1,500, and 2,250 units of phytase activity - FTU - per kg of feed) plus 1 positive control diet without phytase, supplied to male and female birds. The result indicated that the colorimetric methodology with an extraction ratio of 1:20 (mass of sample in g:volume of the solvent extractor in mL) was shown to be the most adequate. There was no interaction between the phytase level and the sex of the broilers (p>0.05). Males consumed 12% more Pphy than did females (p<0.01), but the sex of the broilers did not affect (p>0.05) the excretion and retention coefficient of Pphy. The increase in the phytase level of the diet reduced (linear, p<0.01) the Pphy excretion. The greatest Pphy retention was estimated at 87.85% when the diet contained 1,950 FTU/kg (p<0.01), indicating that it is possible to reduce the inorganic P in the formulation at an amount equivalent to 87.85% of the Pphy content present in the feed, which, in this research, corresponds to a decrease in 2.86 g of P/kg of the feed.
ABSTRACT
Sugar cane (Saccharum spp.) is a forage crop widely used in animal feed because of its high dry matter (DM) production (25 to 40 t/ha) and high energy concentration. The ensiling of sugar cane often incurs problems with the growth of yeasts, which leads to high losses of DM throughout the fermentative process. The selection of specific inoculants for sugar cane silage can improve the quality of the silage. The present study aimed to select strains of lactic acid bacteria (LAB) isolated from sugar cane silage and to assess their effects when used as additives on the same type of silage. The LAB strains were inoculated into sugar cane broth to evaluate their production of metabolites. The selected strains produced higher concentrations of acetic and propionic acids and resulted in better silage characteristics, such as low yeast population, lower ethanol content, and lesser DM loss. These data confirmed that facultative heterofermentative strains are not good candidates for sugar cane silage inoculation and may even worsen the quality of the silage fermentation by increasing DM losses throughout the process. Lactobacillus hilgardii strains UFLA SIL51 and UFLA SIL52 resulted in silage with the best characteristics in relation to DM loss, low ethanol content, higher LAB population, and low butyric acid content. Strains UFLA SIL51 and SIL52 are recommended as starter cultures for sugar cane silage.
