Evaluation of high protein oats as a replacement for corn in diets fed to growing-finishing swine     

M D Lindemann  R J Meade  S G Cornelius  H E Hanke  K P Miller  J W Rust 《Journal of animal science》1983,56(4):853-857

In a series of five trials, 680 crossbred pigs were fed isolysine diets in which high protein (13.8 to 16.0%) oats constituted 0, 20, 40 or 60% of the cereal portion. There was a linear depression in average daily gain (P less than .001) and average daily feed intake (P less than .005) with increasing level of oats, but feed/gain was unaffected (P less than .05) during the growing period from 22 to 46 kg. There were no significant differences in average daily gain during the finishing period from 46 to 102 kg; however, feed/gain increased linearly (P less than .01) with increasing level of oats in the diet. Increases in the percentage of oats in the cereal portion of the diet resulted in a linear (P less than .01) decrease in average daily gain and an increase (P less than .01) in feed/gain for the entire feeding period. We conclude that high protein-high lysine oats of the quality used in these trials can be included at up to 20% of the cereal portion of the diet without greatly affecting performance.  相似文献   

Effect of asynchronous nitrogen and energy supply on growth of ruminal bacteria in batch culture.     

J R Newbold  S R Rust 《Journal of animal science》1992,70(2):538-546

The effects of an asynchronous supply of fixed amounts of N and carbohydrate on bacterial growth were measured in two batch culture experiments. In Exp. 1, aqueous glucose and urea solutions were added at hourly intervals to culture flasks containing strained ruminal liquor and phosphate/bicarbonate buffer. The ratio of urea N to glucose was either constant (Synchrony, 26 mg of N/g of glucose) or increased exponentially over time (Asynchrony, .013 to 48,900 mg of N/g of glucose). After 12 h, identical quantities of glucose and urea had been added in both treatments. Bacterial population size (estimated from optical density) was greater (P less than .001) from 5 to 8 h of incubation for Synchrony than for Asynchrony, but after 12 h there was no difference (P greater than .1) between treatments. In Exp. 2, large (1 to 1.5 mm) and small (less than .5 mm) corn particles were used as slowly and rapidly degraded energy sources, with soybean meal (1 to 1.5 mm) and a papaic digest of soybean meal as sources of slowly and rapidly degraded N. At incubation times, when the ratio between total starch and N degraded was equal between treatments, bacterial population size was unaffected by the relative rate of N and OM supply. In both experiments, bacterial growth recovered quickly from transient restriction caused by deficits of N.  相似文献   

Preliminary Investigations into the Socio-Economic Feasibility of Saltwater Cage Culture of Florida Red Tilapia in Haiti     

Jane L.  Brass Michael B.  Rust  Bori L.  Olla  Robert I.  Wicklund 《Journal of the World Aquaculture Society》1990,21(3):192-200

The primary objective of this study was to investigate the socio-economic feasibility of saltwater cage culture of Florida red tilapia as a new production activity in Haiti. Market outlets and potential prices for saltwater-reared red tilapia in Haiti were examined. Availability and prices of inputs to production were considered. Although this information was collected in the context of Haiti, it is relevant to other developing countries when assessing the potential for a mariculture industry.
Two types of market outlets for saltwater-reared red tilapia were found to exist in Haiti. The predominant rural market sector treated red tilapia as a low-value species and paid an average price ($0.90/kg roundweight) similar to that for freshwater black tilapia. Urban specialty markets treated red tilapia as a premium quality fish and paid an average price ($2.20/kg cleaned) equal to that for snapper and grouper.
Comparison of production costs to potential market prices indicates that saltwater cage culture of tilapia is not economically feasible on an artisanal scale and is a high financial risk on a commercial scale. Break-even prices are higher than prices in the large rural market sector. No data exists to indicate sufficient demand in the smaller urban specialty market sector or export markets.  相似文献   

Effect of hexaflumuron on mortality of the Western subterranean termite (Isoptera: Rhinotermitidae) during and following exposure and movement of hexaflumuron in termite groups   总被引：1，自引：0，他引：1  

Haagsma KA  Rust MK 《Pest management science》2005,61(6):517-531

The effects of hexaflumuron consumption on the mortality of workers of the Western subterranean termite, Reticulitermes hesperus Banks, were observed following various exposures to a substrate treated with 14C-labeled hexaflumuron at 5 g kg(-1). Uptake of hexaflumuron by workers was rapid, peaking at approximately 280 ng hexaflumuron per termite 12 days after exposure. The onset of mortality began at day 8, with cumulative mortality reaching approximately 96% by day 45. Excretion of hexaflumuron from worker termites was rapid following various exposure periods, half-lives ranging from 2.1 to 4.7 days. Trophallaxis among worker termites was efficient, hexaflumuron levels in recipient termites approaching two-thirds of levels present in donor termites feeding continuously on hexaflumuron-treated filter paper. The effect of donor-to-recipient group ratios was negligible on the amounts of hexaflumuron transferred from donors to recipients. In laboratory tests, hexaflumuron diffused from a feeding source within 7 days. The presence of additional food sources appeared to inhibit movement of hexaflumuron. Movement of hexaflumuron by cannibalism and coprophagy occurred, but was significant only when termites were starved. Hexaflumuron also appeared to adversely affect egg development by preventing hatch. Hexaflumuron was readily transferred through termite groups, effectively suppressing laboratory populations of R hesperus. Variable efficacy in field situations employing baiting with hexaflumuron in southern California may be a consequence of sporadic feeding at bait stations, the rapid clearance of hexaflumuron from individual termites, and the difficulties in bait presentation (low foraging activity, poor bait station foraging fidelity) inherent in the foraging characteristics of the Western subterranean termite.  相似文献   

Light-driven changes in energy metabolism directly entrain the cyanobacterial circadian oscillator     

Rust MJ  Golden SS  O'Shea EK 《Science (New York, N.Y.)》2011,331(6014):220-223

Circadian clocks are self-sustained biological oscillators that can be entrained by environmental cues. Although this phenomenon has been studied in many organisms, the molecular mechanisms of entrainment remain unclear. Three cyanobacterial proteins and adenosine triphosphate (ATP) are sufficient to generate oscillations in phosphorylation in vitro. We show that changes in illumination that induce a phase shift in cultured cyanobacteria also cause changes in the ratio of ATP to adenosine diphosphate (ADP). When these nucleotide changes are simulated in the in vitro oscillator, they cause phase shifts similar to those observed in vivo. Physiological concentrations of ADP inhibit kinase activity in the oscillator, and a mathematical model constrained by data shows that this effect is sufficient to quantitatively explain entrainment of the cyanobacterial circadian clock.  相似文献   

Neutral detergent fiber concentration of corn silage and rumen inert bulk influences dry matter intake and ruminal digesta kinetics of growing steers   总被引：2，自引：0，他引：2  

Tjardes KE  Buskirk DD  Allen MS  Ames NK  Bourquin LD  Rust SR 《Journal of animal science》2002,80(3):833-840

Corn silage with high NDF concentration has the potential to reduce DMI because it has a greater filling effect in the rumen than low-NDF corn silage. Our objective was to determine whether ruminal fill influences DMI to the same extent with low- or high-NDF corn silage-based diets. Eight ruminally cannulated Holstein steers (198 +/- 13 kg) were randomly assigned to a 2 x 2 factorial arrangement of treatments in a replicated 4 x 4 Latin square design with 16-d periods. Treatments were diets containing corn silage from a normal hybrid (low-fiber; LF) or its male-sterile isogenic counterpart (high-fiber; HF), offered for ad libitum consumption to steers with or without rumen inert bulk (RIB). The LF and HF diets contained 33.8 and 50.8% dietary NDF, respectively. Rumen inert bulk was added at 25% of pretrial ruminal volume in the form of plastic-coated tennis balls filled with sand to achieve a specific gravity of 1.1 and a total volume of 7.5 L. No fiber level x inert bulk interactions were detected for DMI or NDF intake (P > 0.10), suggesting that DMI was limited to the same extent by physical fill at both levels of dietary fiber. Addition of RIB decreased DMI by an average of 10.7%, which was 65.5 g/L of added bulk. The HF diet depressed DMI by an average of 15.5%, increased NDF intake 27.1%, and reduced ruminal NDF turnover time by 21.0% compared to the LF diet (P < 0.01), with no effect on ruminal volume or amount of NDF in the rumen (P > 0.10). Addition of RIB also reduced ruminal NDF turnover time and amount of NDF in the rumen (11.8% and 20.7%, respectively; P < 0.01), with no change in ruminal digesta volume (P > 0.10). The HF treatment decreased digestibility of DM and GE (5.5 and 5.7%, respectively; P < 0.01) but increased NDF digestibility (10.4%; P < 0.01) compared to LF. Rumen inert bulk had no effect on digestibility of DM, NDF, or GE (P > 0.10). The lack of reduction in digesta volume with addition of inert fill suggests that DMI of light-weight steers receiving corn silage-based diets within a wide range of NDF concentrations was not regulated by ruminal distension alone.  相似文献   

Grazing methods and stocking rates for direct-seeded alfalfa pastures: II. Pasture quality and diet selection     

Schlegel ML  Wachenheim CJ  Benson ME  Ames NK  Rust SR 《Journal of animal science》2000,78(8):2202-2208

A 2-yr study was conducted to determine the effects of two grazing methods (GM) and two stocking rates (SR) on alfalfa (Medicago sativa L. var. WL225) pasture quality and diet selection by Holstein steers. Eight pasture plots (.76 ha) were seeded in 1988 and divided into two blocks of four pastures each. Pastures were managed to allow a 36-d rest period with an average grazing season of 105 d. Before steers entered the next paddock, canopy heights (CH) of alfalfa plants were determined and pasture-forage samples were collected. Forage samples were analyzed for DM, OM, CP, and in vitro OM digestibility (IVOMD). At 12-d intervals beginning with the second grazing cycle, extrusa samples were collected from steers with esophageal fistulas. Extrusa samples were frozen, freeze-dried, and analyzed for OM, CP, IVOMD, in situ ruminal DM degradation, and ruminal undegradable protein. There were no effects of GM on alfalfa CH or pasture DM, OM, CP, and IVOMD. Increasing the SR increased pasture CP content in both years and increased DM, OM, and IVOMD in the 2nd yr. There was no effect of GM or SR on the quality of forage selected by esophageally fistulated steers. Esophageally fistulated steers selected forage that had greater OM, CP, and IVOMD than the average nutrient content of the forage. Although forage quality was greater when stocking rates were increased, the quantity of forage available per animal may have limited gains.  相似文献   

Marking live feeds with inert metal oxides for fish larvae feeding and nutrition studies     

Matthew A Cook  Ronald B Johnson  Pete Nicklason  Harold Barnett  & Michael B Rust 《Aquaculture Research》2008,39(4):347-353

Yttrium oxide (Y₂O₃), ytterbium oxide (Yb₂O₃), lanthanum oxide (La₂O₃) and dysprosium oxide (Dy₂O₃) were evaluated as potential live feed markers for feeding and nutrition studies with fish larvae, by determining the uptake and depletion of markers over time in two trials, and quantifying ingestion of Y₂O₃‐marked rotifers (Branchionus plicatilis) by Atlantic cod (Gadus morhua) in a third trial. In the first two trials, Artemia nauplii and rotifers quickly took up markers within 10 min to concentrations useful for nutrition studies (>2% dry weight). There was no significant difference (P>0.05) among temperatures in depletion of markers (10, 15, 20 °C) with Artemia or rotifers. Depletion from rotifers was not significantly different (P>0.05) between 5 and 20 min nor between 5 and 30 min for Artemia when marked at a concentration of 50 mg of marker per litre of seawater. In the second trial, rotifers and Artemia were marked with a higher concentration (250 mg L^?1) and allowed to deplete for a longer time (90 min). In the third trial, visual estimates of Artemia consumed by Atlantic cod larvae were similar to consumption estimates determined by analysis of Y₂O₃‐marked Artemia using inductively coupled plasma optical emission spectroscopy (r²=0.77).  相似文献   

Use of bovine somatotropin for increased skeletal and lean tissue growth of Holstein steers     

Schlegel ML  Bergen WG  Schroeder AL  VandeHaar MJ  Rust SR 《Journal of animal science》2006,84(5):1176-1187

One hundred-sixty Holstein growing-finishing steers (initial BW of 185 kg) were blocked by BW to determine the effectiveness of long-term bovine somatotropin (bST) administration on lean, skeletal, and carcass measurements. Steers were randomly allocated to 4 treatments (10 steers/treatment) within a block (n = 4 blocks). Treatments were control, no bST (C-C); bST from d 0 to 182 (bST-C); bST from d 183 to slaughter (C-bST); and bST from d 0 to slaughter (bST-bST). Steers received a s.c. injection of placebo or bST at 14-d intervals. Doses were 320 mg of bST/injection from d 0 to 112 and 640 mg of bST/injection from d 113 to slaughter. The last treatment was administered 31 d before slaughter. Steers received a 14% CP (DM basis) diet from d 0 to 182 and 11.5% CP from d 183 to slaughter that consisted of dry, whole-shelled corn and a pelleted protein-mineral supplement. Steers were slaughtered when BW per block averaged 615 kg (d 325, 353, 367, and 381 for the 4 blocks, respectively). Thirty steers were removed from the study because of poor performance with respect to their pen mates, illness, lameness, death, incomplete castration, and incorrect treatment. Serum IGF-I concentrations increased 151% (P < 0.01) from d 7 through 35 in bST-treated steers compared with control steers. During the first 182 d, bST-C and bST-bST steers were heavier (P < 0.01) and had greater (P < 0.01) ADG, G:F, hip height, and hip height gain compared with C-C and C-bST steers. From d 183 to slaughter, C-bST steers had reduced (P < 0.05) daily DMI and greater G:F than bST-C steers. At final slaughter, C-bST and bST-bST steers had greater (P < 0.05) hip height than C-C steers. Noncarcass weight was increased and dressing percent reduced (P < 0.05) in C-bST and bST-bST steers compared with C-C steers. Quality grade was least (P < 0.05) in bST-bST carcasses compared with C-C, whereas bST-C and C-bST carcasses were intermediate. At final slaughter, steers receiving bST had greater (P < 0.05) carcass protein and water composition and lower (P < 0.05) carcass lipid and lipid accretion than C-C steers. Bovine somatotropin was effective in reducing carcass fat and increasing edible lean. Administering bST to young, lightweight steers increased skeletal growth and noncarcass weight without an increase in total carcass weight, but decreased carcass quality.  相似文献   

Solar flares, proton showers, and the space shuttle     

Rust DM 《Science (New York, N.Y.)》1982,216(4549):939-946

The space shuttle era will focus renewed attention on the hazards of the space environment to human habitation. The chief unpredictable hazard for astronauts is energetic proton radiation from solar flares. In some orbits, there is no reasonable level of shielding material that will protect shuttle occupants from potentially lethal doses of radiation. The effects of a solar flare that occurred druing the first flight of the Columbia are discussed and current flare research reviewed. The emphasis is on progress made during the recent international Solar Maximum Year toward understanding the origins of proton showers.  相似文献