Recent advances in filtered-air positive-pressure (FAPP) housing for the production of disease-free chickens     

B W Mitchell  C W Beard  H W Yoder 《Avian diseases》1989,33(4):792-800

Design and performance information on a filtered-air positive-pressure (FAPP) housing system for disease-free poultry flocks is presented. The system includes many special features that result in excellent biological security, easy cleanup and maintenance, efficient control of environment, and a centralized alarm in the event of problems. The system has now housed eight flocks without any major problems. Based on its performance thus far, it should be useful as a reliable housing system for disease-free poultry.  相似文献   

A comparative description of two farmer-managed irrigation systems in Nepal     

Edward D. Martin  Robert Yoder 《Irrigation and Drainage Systems》1988,2(2):147-172

The organization of two farmer-managed irrigation systems in the western hills of Nepal is described by examining the ways in which the activities of water allocation, water distribution, maintenance, and resource mobilization are performed. Due to the topography and environment, these two organizations are structured primarily to mobilize the large amount of labor required for maintenance of the intake and canal. Both organizations precisely define each member's water allocation. In one system, water is allocated in proportion to the area of an individual's land holding, while in the other water allocation is by purchased shares. These two cases were used to analyze the importance of the principle of water allocation for expansion of area irrigated and equity of access to irrigation. Evidence from the two systems shows that in this hill environment water allocation by purchased shares provides the individual incentive and an organizational mechanism for efficient development of irrigation resources. Expansion of area irrigated and equity of access to irrigation were found to be greater in the system which allocates water by purchased shares than where water was allocated in proportion to area irrigated.  相似文献   

Poor anchorage and growth of spur ‘Red Delicious’ apple trees with deep crown roots     

C.G. Lyons  K.S. Yoder  R.E. Byers 《Scientia Horticulturae》1982,18(1):45-47

Spur ‘Red Delicious’ apple Malus domestica (Bork.) trees on MM 111 and seedlings that had been blown over by high winds had greater depth to first root and had thinner trunks than adjacent undamaged trees.  相似文献   

Seasonal biochemical changes in coniferous forest canopies and their response to fertilization     

Billow C  Matson P  Yoder B 《Tree physiology》1994,14(6):563-574

Seasonal changes in concentrations of total nitrogen, free amino acids, chlorophyll, starch and sugar were measured in foliage from fertilized and unfertilized conifer forests in New Mexico and Oregon. In the New Mexico Douglas-fir (Pseudotsuga menziesii var glauca (Beissn.) Franco) forest, fertilization resulted in elevated foliar nitrogen concentrations on all dates, from an average of 9 mg g(-1) in unfertilized trees to 14 mg g(-1) in fertilized trees. In the Oregon western hemlock (Tsuga heterophylla (Raf.) Sarg.) forest, fertilization increased total N by only 15%, from 13 mg g(-1) in unfertilized trees to 15 mg g(-1) in fertilized trees. Foliar nitrogen concentrations on a weight basis were lowest in winter and spring, but did not vary seasonally when expressed on a leaf area basis. Chlorophyll concentrations increased with fertilization and had greater seasonal variation than did total nitrogen concentrations. Chlorophyll concentrations were significantly higher during the growing season than in the winter and spring months. Fertilization did not result in major changes in the proportion of total nitrogen in chlorophyll at either the Oregon or the New Mexico site. Concentrations of free amino acids varied with date and fertilization treatment; in New Mexico, amino acids were highest in the winter sample, whereas in Oregon, they were lowest in winter and spring. At both sites, amino acid concentrations were significantly higher in fertilized trees than in control trees on most dates and the ratios of amino acid-N to total N were also significantly higher in fertilized trees. For both sites, starch concentrations were nearly zero for most of the year, but increased sharply just before bud break and initiation of new growth in the spring. Although fertilization resulted in increased nitrogen concentrations in foliage at both sites, the response in New Mexico was much greater than in Oregon. These results are in agreement with forest productivity data that suggest that growth in the New Mexico site is limited by nitrogen, whereas in the Oregon site it is not.  相似文献   

The North Atlantic spring phytoplankton bloom and Sverdrup's critical depth hypothesis     

Siegel DA  Doney SC  Yoder JA 《Science (New York, N.Y.)》2002,296(5568):730-733

More than 50 years ago, Harald Sverdrup developed a simple model for the necessary conditions leading to the spring bloom of phytoplankton. Although this model has been used extensively across a variety of aquatic ecosystems, its application requires knowledge of community compensation irradiance (IC), the light level where photosynthetic and ecosystem community loss processes balance. However, reported IC values have varied by an order of magnitude. Here, IC estimates are determined using satellite and hydrographic data sets consistent with the assumptions in Sverdrup's 1953 critical depth hypothesis. Retrieved values of IC are approximately uniform throughout much of the North Atlantic with a mean value of 1.3 mol photons meter-2 day-1. These community-based IC determinations are roughly twice typical values found for phytoplankton alone indicating that phytoplankton account for approximately one-half of community ecosystem losses. This work also suggests that important aspects of heterotrophic community dynamics can be assessed using satellite observations.  相似文献   

Inactivation of TNF signaling by rationally designed dominant-negative TNF variants     

Steed PM  Tansey MG  Zalevsky J  Zhukovsky EA  Desjarlais JR  Szymkowski DE  Abbott C  Carmichael D  Chan C  Cherry L  Cheung P  Chirino AJ  Chung HH  Doberstein SK  Eivazi A  Filikov AV  Gao SX  Hubert RS  Hwang M  Hyun L  Kashi S  Kim A  Kim E  Kung J  Martinez SP  Muchhal US  Nguyen DH  O'Brien C  O'Keefe D  Singer K  Vafa O  Vielmetter J  Yoder SC  Dahiyat BI 《Science (New York, N.Y.)》2003,301(5641):1895-1898

Tumor necrosis factor (TNF) is a key regulator of inflammatory responses and has been implicated in many pathological conditions. We used structure-based design to engineer variant TNF proteins that rapidly form heterotrimers with native TNF to give complexes that neither bind to nor stimulate signaling through TNF receptors. Thus, TNF is inactivated by sequestration. Dominant-negative TNFs represent a possible approach to anti-inflammatory biotherapeutics, and experiments in animal models show that the strategy can attenuate TNF-mediated pathology. Similar rational design could be used to engineer inhibitors of additional TNF superfamily cytokines as well as other multimeric ligands.  相似文献   

Nonspecific reactions to Mycoplasma serum plate antigens induced by inactivated poultry disease vaccines   总被引：1，自引：0，他引：1  

H W Yoder 《Avian diseases》1989,33(1):60-68

Nonspecific serum plate agglutination reactions to some avian mycoplasma antigens were induced by injecting chickens with several commercial poultry disease vaccines. All of the vaccines were inactivated, and most of them had oil-emulsion adjuvants. The serum plate agglutination reactions appeared within 2 to 3 weeks post-vaccination and generally persisted for several weeks. The plate test reactions were noted with both Mycoplasma gallisepticum (MG) and M. synoviae (MS) antigens, although the degree and duration of the reactions varied with the vaccine involved and the source of MG and MS plate test antigens. Attempts to prevent the nonspecific reactions by heat-inactivation at 56 C for 30 minutes or by addition of equal volumes of solutions of 2-mercaptoethanol, dithiothreitol, or 3 M sodium chloride were ineffective. No hemagglutination-inhibition activity against MG or MS antigens was induced by the vaccines.  相似文献   

Preparation of Mycoplasma synoviae hemagglutinating antigen and its use in the hemagglutination-inhibition test   总被引：1，自引：0，他引：1  

T H Vardaman  H W Yoder 《Avian diseases》1969,13(3):654-661

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Impact of thetexas beef partnership in extension program on profitability of beef cow-calf herds     

Wikse SE  McGrann JM  Herd DB  Falconer LL  Holland PS  Abello FJ  Rogers GM  Richardson DC  Yoder DR  Ramachandran S 《Journal of the American Veterinary Medical Association》2004,225(2):210-220

OBJECTIVE: To determine whether beef herds could increase profitability by reducing production cost per 100 lb (hundredweight [CWTI; ie, 45.4 kg) of calf through implementation of advice from teams of veterinarians and county extension agents supported by university specialists. DESIGN: Longitudinal study. SAMPLE POPULATION: 6 commercial cow-calf herds comprising 1,927 cows. PROCEDURE: Teams of veterinarians and county extension agents provided advice on 25 profitable ranch management practices to herd owners for 3 years. Use of each practice in herds was measured on a scale of 1 to 5 for baseline year 1999. Similar measurements were made at the end of each year for comparison with baseline values. Outcomes were measured by standardized performance analysis. RESULTS: Mean weaning weight of calves per exposed cow of the 6 herds increased significantly from 1999 (2000, 26.8 kg [59 lb; 17%]; 2001, 49.1 kg [108 lb; 31%]; and 2002, 43.2 kg [95 lb; 27%]). Mean cost per CWT of calf decreased significantly from the 1999 value (2000, -$20.04 [-18%]; 2001, -$33.40 [-29%]; and 2002, -$22.52 [-20%]). Additional profits for the 6 herds were $54,407 in 2000, $135,695 in 2001, and $116,089 in 2002 (3-year total of $306,191). Mean increase in management score of herds was positively correlated with increase in net income and accounted for > 60% of increased profits. CONCLUSIONS AND CLINICAL RELEVANCE: Profitability of beef cow-calf operations can be substantially increased through a team approach by identifying opportunities for improvements in management and helping ranch managers implement profitable practices.  相似文献   

Growth and reproductive performance of ewe lambs fed corn or soybean meal while grazing pasture     

R A Yoder  R E Hudgens  T W Perry  K D Johnson  M A Diekman 《Journal of animal science》1990,68(1):21-27

In a 2-yr study a total of 120 Suffolk and Suffolk-cross ewe lambs, approximately 3 mo of age, were assigned within weight strata to one of three treatments: 1) control, pasture only (C), 2) .09 kg soybean meal/(hd.d) (SBM) plus pasture or 3) .45 kg whole shelled corn/(hd.) plus pasture to compare growth and reproductive performance and to determine lamb selectivity of forage quality and type. Each year, supplements were offered from June through the 3rd wk in November. Ewe lambs were managed as one flock on Kentucky bluegrass (Poa pratensis L.) and tall fescue (Festuca arundinacea Schreb.) pastures except for a brief daily supplementation period when all lambs were brought into a corral and sorted into treatment groups for the feeding. Ewe lambs were exposed to fertile rams from October 1 through the 3rd wk of November each year. Growth rates of ewe lambs grazing pasture alone were slower than those of corn-supplemented ewe lambs and were comparable to those of SBM-supplemented ewe lambs, but reproductive performances were similar (P greater than .05). Date of first detected rise in serum concentrations of progesterone and date of first observed estrus and lambing performance were similar (P greater than .05) among treatments for each year. Compared to hand-clipped forage, forage samples collected by esophageally fistulated lambs were higher (P less than .05) in crude protein and lower (P less than .05) in acid detergent fiber each year, indicating that lambs selectively grazed higher-quality forage. These data indicate that neither protein nor energy limited growth or reproductive performance of these ewe lambs.  相似文献