An improved method for a rapid determination of phytase activity in animal feed.
ABSTRACT 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.
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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.J Anim Physiol a Anim Nutr 08/2013; 98(4). DOI:10.1111/jpn.12106 · 1.32 Impact Factor
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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.Animal Feed Science and Technology 11/2011; 170(1-2):130-135. DOI:10.1016/j.anifeedsci.2011.08.001 · 2.09 Impact Factor
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ABSTRACT: In 2 experiments, a total of 184 pigs (PIC, initial BW of 10.3 and 9.7 kg for Exp. 1 and 2, respectively) were used to develop an available P (aP) release curve for commercially available Escherichia coli-derived phytases. In both experiments, pigs were fed a corn-soybean meal basal diet (0.06% aP) and 2 diets with added inorganic P (iP) from monocalcium phosphate (Exp. 1: 0.075 and 0.15% aP; Exp. 2: 0.07 and 0.14% aP) to develop a standard curve. In Exp. 1, 100, 175, 250, or 500 phytase units (FTU)/kg of OptiPhos 2000 or 200, 350, 500, or 1,000 FTU/kg of Phyzyme XP were added to the basal diet. In Exp. 2, 250, 500, 750, or 1,000 FTU/kg of OptiPhos 2000; 500, 1,000, or 1,500 FTU/kg of Phyzyme XP; or 1,850 or 3,700 FTU/kg of Ronozyme P were added to the basal diet. One FTU was defined as the amount of enzyme required to release 1 µmol of iP per minute from sodium phytate at 37°C. For all phytase products, the manufacturer-guaranteed phytase activities were used in diet formulation. All diets were analyzed for phytase activity using both the Phytex and AOAC methods. Pigs were blocked by sex and BW and allotted to individual pens with 8 pens per treatment. Pigs were killed on d 21, and fibulas were collected and analyzed for bone ash. In both experiments, increasing iP improved (linear, P < 0.01) G:F and percentage bone ash. Pigs fed increasing OptiPhos had improved (Exp. 1: linear, P < 0.001; Exp. 2: quadratic, P < 0.001) percentage bone ash, as did pigs fed increasing Phyzyme XP (linear, P < 0.001). In Exp. 2, increasing Ronozyme P improved (quadratic, P < 0.01) percentage bone ash. Using analyzed values from the AOAC method and percentage bone ash as the response variable, an aP release curve was developed for up to 1,000 FTU/kg of E. coli-derived phytases (OptiPhos 2000 and Phyzyme XP) in P-deficient diets. The prediction equation was Y = -0.000000125X(2) + 0.000236X + 0.016, where Y = aP release (%) and X = analyzed phytase (FTU/kg) in the diet.Journal of Animal Science 11/2010; 88(11):3631-44. DOI:10.2527/jas.2010-2936 · 1.92 Impact Factor