Nitrogen utilization and digestibility of amino acids by lambs fed a high-concentrate diet with limestone or magnesium oxide.
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Effects were evaluated of high dietary levels of magnesium oxide (MgO) or limestone on DM, OM and CP digestibility, N balance and intestinal absorption of amino acids by lambs fed a high concentrate diet. Twelve wether lambs equipped with abomasal and ileal cannulas were blocked by weight and breeding and allotted to treatments in a randomized block design in two consecutive trials. Diets were control (800 g), control plus 1.5% MgO (812 g), control plus 1.5% limestone (812 g) and control plus 3.0% limestone (824 g) fed in two equal portions at 12-h intervals. Ruminal fluid pH differences were small. The pH of ileal digesta was greater (P less than .05) with MgO than with limestone (8.23 vs 7.73). Fecal pH was higher (P less than .01) for lambs fed all mineral treatments (avg 8.75) than for lambs fed the control (7.61) and was higher (P less than .01) when MgO (9.53) rather than limestone (8.36) was fed. Ruminal NH3N was lower (P less than .01) when lambs were fed MgO (11.9 mg/dl) compared with limestone (avg 31.2 mg/dl). Preintestinal DM digestibility was greatest (P less than .10) with limestone (avg 49.5%) feeding compared with feeding MgO (31.2%) or the control (35.4%). About 41.5% more essential (P less than .05) and 48% more nonessential (P less than .03) amino acids reached the small intestine when MgO was fed than when limestone was fed. Partial digestibility of amino acids in the small intestine was reduced (P less than .03) an average of 5 percentage units when MgO or limestone was fed. Feeding high levels of MgO or limestone to lambs did not improve the overall digestibility of DM, OM or CP. In fact, feeding high levels of MgO or limestone appeared to be detrimental, reducing intestinal absorption of amino acids. (+info)
Intestinal acid flow, dry matter, starch and protein digestibility and amino acid absorption in beef cattle fed a high-concentrate diet with defluorinated rock phosphate, limestone or magnesium oxide.
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Five Angus heifers (285 kg) with duodenal and ileal cannulas were used to study the effects of feeding mineral acid neutralizers on digesta and fecal pH, intestinal acid flow, DM, starch and CP digestion and amino acid absorption in cattle fed a high-concentrate diet (7.5 kg/d). The experimental design was a 5 x 5 latin square. Treatments included control diet alone or control diet with the addition of 1.60% defluorinated rock phosphate-medium (DRP-M, 77% greater than 150 mu but less than 1,180 mu), 1.60% defluorinated rock phosphate-coarse (DRP-C, 85% greater than 850 mu but less than 1,700 mu), 1.28% limestone (92% greater than 150 mu but less than 850 mu) or .50% MgO, (81% greater than 250 mu but less than 1,180 mu), as an as-fed basis. Ileal pH was increased (P less than .05) from 7.49 to 7.85 by MgO. Fecal pH was increased (P less than .05) in this order: MgO (7.18) greater than DRP-M (6.86) = limestone (6.86) = DRP-C (6.75) greater than control (6.54). Liquid flow to the duodenum was increased (P less than .05) an average of 19.7% by the mineral treatments. Duodenal acid concentrations (mEq/liter) were greatest (P less than .05) for DRP-M (65.4) and DRP-C (64.0) vs limestone (55.5) and MgO (54.4). Acid flow to the intestine was increased (P less than .05) to 4.02, 4.53 and 4.82 Eq/d for animals fed limestone, DRP-M and DRP-C, respectively, from 3.51 Eq/d for control animals. Total tract DM, starch and CP digestibilities were similar (P greater than .10) among treatments. Limestone and DRP-M increased (P less than .10) the partial digestibility of most amino acids by about 6.8%. Mineral treatments did not increase total tract digestion of starch or CP. However, cattle fed DRP-M and limestone may have used protein more efficiently. (+info)
Enhanced stability of CaO and/or La2O3 promoted Pd/Al2O3 egg-shell catalysts in partial oxidation of methane to syngas.
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Sputter growth and characterization of metamagnetic B2-ordered FeRh epilayers.
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Chemically ordered alloys are useful in a variety of magnetic nanotechnologies. They are most conveniently prepared at an industrial scale using sputtering techniques. Here we describe a method for preparing epitaxial thin films of B2-ordered FeRh by sputter deposition onto single crystal MgO substrates. Deposition at a slow rate onto a heated substrate allows time for the adatoms to both settle into a lattice with a well-defined epitaxial relationship with the substrate and also to find their proper places in the Fe and Rh sublattices of the B2 structure. The structure is conveniently characterized with X-ray reflectometry and diffraction and can be visualised directly using transmission electron micrograph cross-sections. B2-ordered FeRh exhibits an unusual metamagnetic phase transition: the ground state is antiferromagnetic but the alloy transforms into a ferromagnet on heating with a typical transition temperature of about 380 K. This is accompanied by a 1% volume expansion of the unit cell: isotropic in bulk, but laterally clamped in an epilayer. The presence of the antiferromagnetic ground state and the associated first order phase transition is very sensitive to the correct equiatomic stoichiometry and proper B2 ordering, and so is a convenient means to demonstrate the quality of the layers that can be deposited with this approach. We also give some examples of the various techniques by which the change in phase can be detected. (+info)
Evaluation of analgesic and anti-inflammatory effect of nanoparticles of magnesium oxide in mice with and without ketamine.
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