The current direct colorimetric assay for phytase activity in feeds has interference from high P background and other factors. Our objective was to develop a rapid and reliable spin column method to accurately determine phytase activity in feed ingredients or complete diets. After the feed sample was extracted by stirring in 0.2 M citrate buffer, pH 5.5, for 30 min at room temperature, the oily layer of the supernatant fraction was removed by passing through an acrodisc syringe filter (0.45-microm HT Tuffryn membrane, Gelman Laboratory, Ann Arbor, MI). The filtrate was then loaded onto a spin column (MW cutoff 30,000, Millipore, Bedford, MA) to remove free phosphate before the phytase activity assay. Compared with the direct assay, this new procedure improved both accuracy and reproducibility. When diets contained phytase at 0 to 1,500 U/kg (as fed), the CV for multiple assays of the same samples (n = 6) by the new method ranged from 1 to 6% compared with 28 to 39% by the direct method. A linear relationship was found between the added phytase activity in practical diets and the analyzed activity by the new method (r2 = 0.99; P < 0.01). In conclusion, the spin column method is an improved assay for phytase activity in animal feed, and may be used for quality control of phytase supplementation.
"Feed phytate-P was determined as described by Kwanyuen and Burton (2005) using acid extraction, followed by high performance liquid chromatography analysis (HPLC, model 1993, Shimadzu, Japan). The actual phytase activity of experimental diets was analysed using a spin column method as described by Kim and Lei (2005). Prior to analysis, the feed samples were ground and mixed thoroughly. "
[Show abstract][Hide abstract] ABSTRACT: The trial was performed to investigate the effects of different concentrations of non-phytate phosphorus (nPP) in the starter and grower (with phytase inclusion) periods on carcass characteristics, organ weight and weekly variations of growth performance in the grower period. Seven hundred and twenty-day-old male broiler chickens were randomly assigned to 12 treatments in a completely randomized design. Chickens received two dietary treatments (4.5 g/kg and 6 g/kg nPP) in the starter (0-21 days) and six experimental diets (4 g/kg, 3.1 g/kg, 2.3 g/kg and 2.3 g/kg + 1000 FTU/Kg of feed phytase, 1.5 g/kg, 1.5 g/kg nPP + 1000 FTU/Kg of feed phytase) in the grower period (22-42 days). Results showed that phytase inclusion in the second and third weeks of grower period could increase feed intake significantly. Also, decrease in the concentrations of nPP to 1.5 g/kg caused to decline body weight gain markedly. Moreover, there is a significant difference between 4.5 g/kg and 6 + 4 g/kg nPP (starter+grower) and 1.5 g/kg nPP. Phytase inclusion increased carcass yield and declined liver weight significantly. Dietary treatment of 4.5 + 1.5 g/kg nPP enhanced heart and liver weight markedly. It is concluded that starter diets with increased concentration of nPP (6 g/kg nPP) had no beneficial effects on growth performance in the starter and grower period in the total (0-42 days). Also, it is possible to decrease nPP concentration of grower diets to 1.5 and 2.3 g/kg with and without phytase inclusion respectively.
"The reaction was incubated at 27°C for 60 min and was terminated by the addition of an equal volume of 10% trichloroacetic acid (TCA). The reaction mixture was then processed for a color reaction, which allows for quantification of the released Pi compared to standard dilutions of KH2PO4 (Kim and Lei 2005). The Pi concentration was measured by reading the absorbance at 820 nm after color development with fresh color reagent at 50°C for 15 min (Kim and Lei 2005). "
[Show abstract][Hide abstract] ABSTRACT: Alfalfa (Medicagosativa L.) is one of the most widely grown crops in the USA. Phosphate (P) deficiency is common in areas where forage crops are grown. To improve the use of organic phosphate by alfalfa, two Medicagotruncatula genes, phytase (MtPHY1) and purple acid phosphatase (MtPAP1), were overexpressed in alfalfa under the control of the constitutive CaMV35S promoter or the root-specific MtPT1 promoter. Root enzyme activity analyses revealed that although both genes lead to similar levels of acid phosphatase activities, overexpression of the MtPHY1 gene usually results in a higher level of phytase activity than overexpression of the MtPAP1 gene. The MtPT1 promoter was more effective than the CaMV35S promoter in regulating gene expression and extracellular secretion under P-deficient conditions. Measurement of growth performance of the transgenic lines further proved that the best promoter–gene combination is the MtPHY1 gene driven by the MtPT1 promoter. Compared to the control, the plants with high levels of transgene expression showed improved growth. The biomass of several transgenic lines was three times that of the control when plants were grown in sand supplied with phytate as the sole P source. When the plants were grown in natural soils without additional P supplement, the best performing transgenic lines produced double the amount of biomass after 12 weeks (two cuts) of growth. Transgene effects were more obvious in soil with lower pH and lower natural P reserves than in soil with neutral pH and relatively higher P storage. The total P concentration in leaf tissues of the high-expressing transgenic lines was significantly higher than that of the control. The transgenes have great potential for improving plant P acquisition and biomass yield in P-deficient agricultural soils.
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"Due to the mixture of coarse and fine particles of WM, and its highly fermentable carbohydrates, WM must therefore be evenly mixed in ruminant rations (ZoBell et al., 2003). Wheat middlings have been fed to livestock species such as poultry (Laudadio et al., 2011), swine (Kim and Lei, 2005), dairy cattle (Bargo et al., 2006) and ewes (Tufarelli and Laudadio, 2011). In particular, WM fed to beef and dairy cows in comparison Table 1 Ingredient and chemical composition of diets containing wheat middlings (WM) in TMR fed to lambs. "
[Show abstract][Hide abstract] ABSTRACT: a b s t r a c t Little scientific information is available that evaluates wheat middlings (WM) as corn grain substitute in lamb diet. The objective of this work was to evaluate the effect of feeding WM in total mixed rations (TMR) on lamb performance and carcass characteristics. Forty Comisana breed male lambs (13 ± 0.5 kg BW) were allocated randomly to two isocaloric and isonitrogenous diets. Two pelleted TMR were formulated: control diet contained 400 g/kg of dry matter (DM) of corn as main starch source, whereas experimental diet contained 600 g/kg DM of WM. Lambs were slaughtered after fifty days of feeding trial and carcass data were collected. In order to evaluate in vivo digestibility of TMR, four adult Comisana rams were placed in metabolic cages and their individual faeces and urine were collected, and indicated differences for NDF and ADF fractions. Results from growth trial of lambs showed that final live weight and gain as well as feed conversion ratio were improved by WM in diet (P=0.035). In slaughter trial, none of the parameters studied were influ-enced by dietary treatment, except for slaughter weight and cold-carcass dressing that were improved in lambs fed WM (P=0.047 and P=0.042, respectively). Additionally, WM diet had no effect on lamb carcass traits. As result, WM maintained lamb performance and had no negative effect on lamb performance and carcass traits. Maximizing the use of WM may become economically feasible for lamb feeders when prices turn favorable compared to conventional dietary ingredients such as corn.
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