Utilização de nutrientes em frangos alimentados com dietas suplementadas com fitase e níveis reduzidos de fósforo não-fítico Utilization of nutrients in broilers fed diets supplemented with phytase and reduced nonphytate phosphorus levels

Avaliaram-se a digestibilidade ileal, retenção de nutrientes e valores de energia metabolizável aparente (EMA) de dietas suplementadas com fitase e níveis reduzidos de fósforo não-fítico (FNF) para frangos de corte. Foram utilizados 330 pintos machos em delineamento em blocos ao acaso e esquema fatorial 2 x 3 com dois níveis de fitase (0 e 25U/kg) e três níveis de FNF (100, 85 e 70% das exigências da ave), totalizando seis tratamentos com cinco repetições de 11 aves cada. Não houve efeito da interação FNF vs fitase e dos níveis de FNF ou fitase sobre a retenção de matéria seca e de fósforo, e a interação FNF vs fitase foi significativa para retenção de proteína bruta e coeficiente de digestibilidade ileal da matéria seca. A suplementação com fitase, independente dos níveis de FNF, melhorou o coeficiente digestibilidade ileal da proteína bruta, do cálcio e do fósforo. A retenção de cálcio e a redução dos níveis de FNF diminuíam a metabolização da energia bruta das dietas com 85 e 70% das exigências de FNF. Dietas com nível de 70% das exigências de FNF, suplementadas com fitase, podem ser usadas para frangos de corte sem prejuízos à digestibilidade ileal e retenção da matéria seca, proteína bruta, cálcio e fósforo e à metabolização da energia bruta.<br>The ileal digestibility, the retention of nutrients, and the apparent metabolizable energy (AME) values of diets supplemented with phytase and low levels of nonphytate phosphorus (NPP) for broilers were evaluated. Three hundred and thirty male birds were used. The experiment was designed in randomized blocks in a factorial arrangement 2x3 with two phytase levels (0 and 25U/kg) and three NPP levels (100, 85, and 70% of the bird requirement in each phase), with five replicates of 11 broiler for each experimental unit. Effects of NPP vs phytase interaction and NPP and phytase levels on dry matter (DM) and phosphorus (P) retention were not observed; but significant effects of NPP vs phytase on crude protein (CP) retention and DM ileal digestibility coefficient (IDC). Phytase supplementation, independently of NPP levels, improved CPIDC, CaIDC, PIDC, and Ca retention and the lower NPP levels decreased the gross energy metabolization in diets with 85 and 70% of NPP requirements. Diets with NPP level corresponding to 70% of the bird requirements, supplemented with phytase, can be used for broiler with no negative effect on ileal digestibility and retention of dry matter, crude protein, calcium and phosphorus, and on apparent metabolizable energy

Construction of recombinant industrial Saccharomyces cerevisiae strain with bglS gene insertion into PEP4 locus by homologous recombination*

The bglS gene encoding endo-l,3-1,4-β-glucanase from Bacillus subtilis was cloned and sequenced in this study. The bglS expression cassette, including PGK1 promoter, bglS gene fused to the signal sequence of the yeast mating pheromone α-factor (MFα1S), and ADH1 terminator with G418-resistance as the selected marker, was constructed. Then one of the PEP4 allele of Saccharomyces cerevisiae WZ65 strain was replaced by bglS expression cassette using chromosomal integration of polymerase chain reaction (PCR)-mediated homologous recombination, and the bglS gene was expressed simultaneously. The recombinant strain S. cerevisiae (SC-βG) was preliminarily screened by the clearing hydrolysis zone formed after the barley β-glucan was hydrolyzed in the plate and no proteinase A (PrA) activity was measured in fermenting liquor. The results of PCR analysis of genome DNA showed that one of the PEP4 allele had been replaced and bglS gene had been inserted into the locus of PEP4 gene in recombinant strains. Different endo-l,3-1,4-β-glucanase assay methods showed that the recombinant strain SC-βG had high endo-l,3-1,4-β-glucanase expression level with the maximum of 69.3 U/(h·ml) after 60 h of incubation. Meanwhile, the Congo Red method was suitable for the determination of endo-l,3-1,4-β-glucanase activity during the actual brewing process. The current research implies that the constructed yeast strain could be utilized to improve the industrial brewing property of beer