Growing cattle in the United States consume up to 6 kg of starch daily, mainly from corn or sorghum grain. Total tract apparent digestibility of starch usually ranges from 90 to 100% of starch intake. Ruminal starch digestion ranges from 75 to 80% of starch intake and is not greatly affected by intake over a range of 1 to 5 kg of starch/d. Starch apparently digested in the small intestine decreases from 80 to 34% as starch entering the small intestine increases from 0.2 to 2 kg/d. Starch apparently digested in the large intestine ranges from 44 to 46% of starch entering the large intestine. Approximately 70% of starch digested in the small intestine appears as glucose in the bloodstream. Within the range of starch intakes that do not cause rumen upsets, increasing starch (and energy) intake increases the amount of starch digested in the rumen, increases the supply of starch to the small intestine, increases starch digested in small intestine (albeit at reduced efficiency), and increases starch digested in the large intestine, such that total tract digestibility remains relatively constant. With increased starch intake, most of the starch is still digested in the rumen, but increasing amounts of starch escape ruminal and intestinal digestion, and disappear distal to the ileocecal junction. Again, within the range of starch intakes that do not cause rumen upsets, as starch intake increases, hepatic gluconeogenesis increases, glucose entry increases, and glucose irreversible loss increases, with a significant portion lost as CO2. The ability to increase use of dietary starch to support greater weight gains or improved marbling could come from increasing starch digestion in a healthy rumen or in the small intestine, but we conclude that the main limit to use of dietary starch to support live weight gain is digestion and absorption from the small intestine. Increased oxidation of glucose at greater starch intakes may alter energetic efficiency by sparing other oxidizable substrates, like amino acids.

Background New school meal standards are currently being phased in by the government in an attempt to improve the nutritional composition of school food. However, no standards are applied to packed lunches. The present study aimed to compare the food and nutrient intakes of primary school children eating a school meal with those taking a packed lunch.

Cellulose sulfate, a polyanionic compound derived from cotton, has been proposed as a topical microbicide to reduce the sexual transmission of HIV. However, a phase III clinical trial of a vaginal gel formulation of cellulose sulfate (Ushercell) had to be prematurely closed after early data indicated microbicide users had a higher rate of HIV infection than women using a placebo. The unexpected results of the cellulose sulfate trail prompted us to reexamine and attempt to replicate the available preclinical data for this compound and other polyanions. We show here that cellulose sulfate has a biphasic effect on HIV infection in vitro: at high concentrations it inhibits infection but at low concentrations it significantly and reproducibly increases HIV infection. This stimulatory effect is evident for the R5-tropic strains of virus responsible for sexual transmission, reflects the rate of infection rather than viral growth, and occurs at clinically relevant concentrations of the compound. An examination of published studies shows that the biphasic effect of cellulose sulfate was evident in previous research by independent laboratories and is also found for other polyanions such as dextrin sulfate and PRO2000. These data help in understanding the failure of the Ushercell clinical trial and indicate that cellulose sulfate is not safe for mucosal application in humans. 925T HERE IS AN URGENT NEED for safe and effective topical microbicides to reduce the sexual transmission of HIV. Among the various classes of molecules proposed for this purpose, there has been particular clinical interest in sulfated polymeric anionic compounds such as cellulose sulfate (a high-molecular-weight ␤1,4-glucose polymer derived from cotton), carrageenan (a polygalactose ϩ 3,6-anhydrogalactose copolymer extracted from seaweed), dextrin sulfate (a synthetic ␣1,4-D-glucose polymer), and PRO2000 (a synthetic naphthalene sulfonate polymer). 1,2 These compounds are thought to nonspecifically inhibit HIV entry into target cells by interacting with basic regions of the viral envelope. 3 Recently, however, the concept of polyanion microbicides was dealt a major setback when the Contraceptive Research and Development Program (CONRAD) announced that they had halted a phase III clinical trial of a formulated cellulose sulfate vaginal gel (Ushercell) being conducted in South Africa, Benin, Uganda, and India because the independent data monitoring committee detected increased HIV infection rates in the women who received cellulose sulfate compared to placebo gel. 4,5 The premature closure of the cellulose sulfate phase III trial prompted us to reexamine and attempt to replicate the available preclinical data for this compound and other polyanions. The current work focuses on the question of how such compounds affect HIV infection in vitro, an essential prerequisite for human testing. Our main finding is that cellulose sulfate at concentrations that would be present in humans using Ushercell can increase infection by sexually transmitted R5-tro...

Heifers with expected increased risk of bovine respiratory disease (BRD; n = 360; initial BW = 241.3 +/- 16.6 kg) were assembled at a Kentucky order-buyer facility and delivered to Stillwater, OK, in September 2007 to determine the effects of clinical BRD observed during preconditioning on subsequent feedlot performance, carcass characteristics, and meat attributes. During a 63-d preconditioning period, morbidity and mortality attributed to BRD were 57.6 and 8.6%, respectively. Immediately after preconditioning, heifers were grouped according to health outcome category and allotted to finishing pens (5 to 7 heifers/pen). Heifers were never treated for BRD (0X; n = 9 pens), treated 1 time (1X; n = 9 pens), 2 times (2X; n = 6 pens), 3 times (3X; n = 6 pens), or designated as chronically ill (CI; n = 2 pens). Arrival BW was not different (P = 0.21) among treatment categories. However, disease incidence during preconditioning decreased (P < 0.001) growth, resulting in BW of 318, 305, 294, 273, and 243 kg for 0X, 1X, 2X, 3X, and CI, respectively, at the start of the finishing phase. Estimates on the LM, taken by ultrasound on d 65 and 122, were combined with BW and visual appraisal to target common average endpoint within category and block. On average, heifers were slaughtered on d 163 for 0X, 1X, and 2X, d 182 for 3X, and d 189 for CI (P < 0.01). Final BW was similar (P > or = 0.18) for heifers treated 0, 1, 2, or 3 times, but heifers deemed CI weighed less (P = 0.01) than 3X heifers. Considering the finishing phase only, ADG was linearly increased (P < 0.001) with increasing BRD treatments, but was linearly decreased (P = 0.003) as BRD treatments increased from arrival to slaughter. Therefore, G:F was greater (P = 0.007) for CI than 3X and linearly increased (P = 0.002) from 0X to 3X. Similar to BW, HCW was less (P = 0.03) for CI than 3X. Marbling score tended (P = 0.06) to decrease linearly as the number of treatments increased, but no other differences (P > or = 0.24) in carcass traits were detected. No differences were observed in beef tenderness (P = 0.65), and no consistent trends were noted in retail display or palatability data. Less than 20 additional days on feed were required for heifers treated 3 times to have similar BW and carcass characteristics to heifers never treated for BRD. Segregating animals with multiple BRD treatments and feeding them to an acceptable carcass endpoint may be a viable strategy for increasing value of animals treated for BRD.