Effects of feeding high-oil corn to beef steers on carcass characteristics and meat quality

To assess the effects of feeding high-oil corn on carcass characteristics and meat quality, 60 yearling steers were fed high concentrate diets containing either control corn (82% of diet), high-oil corn (82% of diet), or high-oil corn at a concentration that was isocaloric with the control diet (74% of diet). After being fed for 84 d, steers were slaughtered. At 72 h postmortem, carcass data were collected and rib sections from five steers grading U.S. Choice and five steers grading U.S. Select from each treatment were collected, vacuum packaged, and aged for 14 d. Three steaks (2.54 cm thick) were removed from each rib for Warner-Bratzler shear force measurement, sensory appraisal, and fatty acid composition analyses. Data were analyzed with treatment as the main effect for the carcass data and treatment, quality grade, and two-way interaction in the model for the longissimus data. The two-way interaction was nonsignificant (P > 0.05) for all variables tested. No differences were detected (P > 0.05) in carcass measurements except for marbling scores and quality grades, both of which were greater (P < 0.05) for carcasses from steers fed the high-oil corn. Overall, 78% of steers fed the high-oil corn graded U.S. Choice compared with 47% for the control and 67% for isocaloric group. Shear force and sensory properties of the longissimus were not different (P > 0.05) among treatments. Steaks from U.S. Choice carcasses rated higher (P < 0.05) for tenderness and tended to rate higher (P < 0.10) for juiciness. Feeding the isocaloric and high-oil diets increased (P < 0.05) linoleic acid, arachidonic acid, and the total PUFA content of lipid extracted from the longissimus. Saturated fatty acid percentage was lowest (P < 0.05) for high-oil corn and highest (P < 0.05) for control, with isocaloric being intermediate. Feeding high-oil corn increased (P < 0.05) pentadecyclic acid, margaric acid, and total odd-chain fatty acid content. Feeding high-oil corn in finishing beef cattle diets enhanced intramuscular lipid deposition and increased unsaturation of fatty acids of the longissimus.     

High dietary calcium to phosphorus ratio and alkali-forming potential as factors promoting silica urolithiasis in sheep

Sheep were used to study factors previously found to promote silica urolithiasis in a rat model. In addition to high silica, these dietary factors included elevated calcium, a high calcium to phosphorus ratio and alkali-forming effects. Wether lambs had ad libitum access to a diet of 50% of grass hay and 50% ground oats plus supplement. Diet analysis was 3.4% total SiO2, .29% calcium, .25% phosphorus, 11.3% CP and 28% ADF. Treatments (40 lambs/treatment) consisted of a control (C), limestone to increase dietary calcium to .6% (L), L + 1% sodium bicarbonate (LS) and L + 1% ammonium chloride (LA). After a 91-d experimental period followed by a 56-d postexperimental finishing period, silica kidney deposits were found in all treatments, and SiO2 made up 74% to 97% of the urolithic ash. Kidney urolith incidences in the four treatments were C, 7/40; L, 12/40; LS, 20/40; and LA, 9/40. A higher urolith incidence in LS (LS vs C, P less than .05) and a trend toward a higher incidence in L (L vs C, P less than .2), accompanied by elevated urine pH (L = LS greater than C greater than LA, P less than .01), lend support to the concept that high-silica diets having high calcium to phosphorus ratios and alkali-forming potentials contribute to silica urolithiasis.     

Use of surface plasmon resonance (SPR) to study the dissociation and polysaccharide binding of casein micelles and caseins

Tests were made to determine whether surface plasmon resonance (SPR) could be used as a technique to study the dissociation properties of bovine casein micelles or of sodium caseinate and the interactions between these protein particles and different polysaccharides. Surfaces of bound micelles or caseinate were made, and the changes in refractive index of these layers were used to define changes in the structures of the chemisorbed material. The technique appears to have some potential for studying details of the dissociation of casein micelles and of the binding of different polysaccharides to caseins.     

Effects of preconditioning on pre- and post-shipment performance of feeder calves

A preconditioning (PC) program that involved preweaning vaccination and preshipment weaning was evaluated utilizing 600 calves produced on four South Dakota ranches. Nonpreconditioned (NPC) controls were herd mates that were maintained with their dams during the preconditioning process. All calves were shipped from the ranch to the feedlot on the same date. In Exp. I, PC caused lower (P less than .001) preshipment gains. However, management x ranch and management x year effects indicated that response to PC was variable. Preconditioning reduced (P less than .001) transit shrink in Exp. I but caused greater (P less than .05) shrink in Exp. II. Ranch and management x ranch effects accounted for more of the variation in shrink than PC did. In the feedlot, PC calves consumed more feed initially (d 1 to 28; P less than .001) and during the entire (P less than .10) feeding period when fed to slaughter condition. During the 28-d postshipment period, calves fed higher-grain diets consumed more feed (P less than .001) and were less efficient (P less than .001) than calves fed corn silage. When fed for longer periods (greater than 28 d), higher-energy diets improved feedlot gains and feed efficiency independent of preconditioning. Health and performance responses to this preconditioning procedure were variable. Our preconditioning procedure did not improve beef production efficiency.     

An ion balance for ultra-high-precision atomic mass measurements

We have developed the analog of a double-pan balance for determining the masses of single molecular ions from the ratio of their two cyclotron frequencies. By confining two different ions on the same magnetron orbit in a Penning trap, we balance out many sources of noise and error (such as fluctuations of the magnetic field). To minimize the systematic error associated with the Coulomb interaction between the two ions, they are kept about 1 millimeter apart from each other, resulting in fractional uncertainty below 1 x 10(-11). Such precision opens the door to numerous applications of mass spectrometry, including metrology, fundamental physics, and weighing chemical bonds.     

A conserved checkpoint monitors meiotic chromosome synapsis in Caenorhabditis elegans

We report the discovery of a checkpoint that monitors synapsis between homologous chromosomes to ensure accurate meiotic segregation. Oocytes containing unsynapsed chromosomes selectively undergo apoptosis even if a germline DNA damage checkpoint is inactivated. This culling mechanism is specifically activated by unsynapsed pairing centers, cis-acting chromosome sites that are also required to promote synapsis in Caenorhabditis elegans. Apoptosis due to synaptic failure also requires the C. elegans homolog of PCH2, a budding yeast pachytene checkpoint gene, which suggests that this surveillance mechanism is widely conserved.     

Traces of human migrations in Helicobacter pylori populations

Helicobacter pylori, a chronic gastric pathogen of human beings, can be divided into seven populations and subpopulations with distinct geographical distributions. These modern populations derive their gene pools from ancestral populations that arose in Africa, Central Asia, and East Asia. Subsequent spread can be attributed to human migratory fluxes such as the prehistoric colonization of Polynesia and the Americas, the neolithic introduction of farming to Europe, the Bantu expansion within Africa, and the slave trade.