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321.
322.
Symmetry plays a key role in simplifying the control of legged robots and in giving them the ability to run and balance. The symmetries studied describe motion of the body and legs in terms of even and odd functions of time. A legged system running with these symmetries travels with a fixed forward speed and a stable upright posture. The symmetries used for controlling legged robots may help in elucidating the legged behavior of animals. Measurements of running in the cat and human show that the feet and body sometimes move as predicted by the even and odd symmetry functions.  相似文献   
323.
The structure of Aspergillus flavus communities associated with south Texas cottonseed was determined by analysing samples from 178 truckloads of commercial cottonseed from 35 gins, extending from Fort Bend County in the north to the Rio Grande Valley in the south, from September 1999 to October 2001. The number of colony-forming units (CFU) of A. flavus on the cottonseed, and the percentage of S strain (%S) were both correlated with aflatoxin contamination of cottonseed. The number of CFU differed between both regions and seasons, while %S differed only between regions. Comparison of maps of CFU and %S revealed that CFU shows a higher variation across years, while %S shows higher spatial variation. The Rio Grande Valley had significantly lower CFU and %S strain than the Coastal Bend and Upper Coast regions. Cottonseed produced in 1999 had significantly more A. flavus than that produced in either 2000 or 2001. Identification of factors dictating geographical variation in S-strain incidence may provide insights that will lead to improved aflatoxin management.  相似文献   
324.
The object of this investigation was to determine the outcome of limb amputation in wapiti. Medical records of 13 wapiti that underwent limb amputation were reviewed to determine age, weight, sex, injury preceding amputation, limb amputated, amputation location, length of hospital stay, complications, and outcome. Ages ranged from 3 months to 8 years and weights from 70 kg to 280 kg. All animals were female. Eleven animals sustained catastrophic long bone fractures prior to amputation. Five animals had front limb amputations and 8 had hind limb amputations. Of these animals, 1 with a front limb amputaiton and 5 with hind limb amputations survived. Postsurgical inability to stand is associated with hospitalization of > 1 day. Of the 13 wapiti reviewed, 5 with hind limb amputations have produced and reared offspring. Hind limb amputation can be considered a viable alternative to euthanasia when catastrophic orthopedic injuries occur in female wapiti.  相似文献   
325.
Significant efforts should be devoted to reducing waste outputs from aquaculture operations in order to lower the environmental impacts of aquaculture in many parts of the world. Since most aquaculture wastes are ultimately from dietary origin, reduction of waste outputs should first be through improvements of diet formulation and feeding strategies. The first step in the production of feeds producing less solid waste is to eliminate poorly digestible ingredients (such as whole grain or grain by-products used as binders and fillers in the feed formulae) and to use highly digestible ingredients with good binding properties. Further reduction of solid waste can then be achieved through careful selection of the ingredients to improve apparent digestibility and the nutrient balance of the feed. Nitrogen waste outputs can be reduced through the reduction of the digestible protein to digestible energy (DP/DE) ratio of the diet. Phosphorus waste outputs can be reduced through careful selection of the ingredients and optimization of the digestible phosphorus content of the diet to meet the requirement of the fish but avoid greatly exceeding this required level. Finally, feeding practices that minimize feed wastage should be adopted since feed wastage can have a very significant impact on waste outputs from fish culture operations.  相似文献   
326.
Genetic diversity estimates in Cicer using AFLP analysis   总被引:2,自引:0,他引:2  
Amplified fragment length polymorphism (AFLP) analysis was used to evaluate the genetic variation among cultivated chickpea and wild Cicer relatives. In total, 214 marker loci were assessed, of which 211 were polymorphic (98.6%) across the 95 accessions that represented 17 species of Cicer. The genetic variation within a species was highest in C. pinnatifidum followed by C. reticulatum and lowest in C. macracanthum. Three main species groups were identified by UPGMA clustering using Nei's pair‐wise distance calculations. Group I included the cultivated species C. arietinum, C. reticulatum and C. echinospermum. Within this group, C. reticulatum accessions were clustered closest to the C. arietinum cultivars ‘Lasseter’, ‘Kaniva’ and ‘Bumper’, supporting the hypothesis that C. reticulatum is the most probable progenitor of the cultivated species. Cicer bijugum, C. judaicum and C. pinnatifidum were clustered together creating group II. Group III contained all nine perennial species assessed and two annual species C. yamashitae and C. cuneatum. The genetic distance detected between group I and group III (0.13) was equivalent to the genetic distance detected between group I and group II (the primary and annual tertiary species, respectively; 0.14). This indicated that the perennial tertiary species may be as valuable for increasing variation to incorporate novel germplasm in the cultigen as the annual tertiary species.  相似文献   
327.
1. The fatty acid profile of egg yolk and vitamin E and carotenoid accumulation in the egg yolk and embryonic tissues were investigated in relation to the maternal diet. 2. Two hundred fertile eggs (Ross 308 Broiler Breeder), obtained from hens fed on a maize-based (M-diet) or a wheat-based diet (W-diet), were incubated using standard conditions. 3. The egg yolk and embryo tissues (residual yolk, yolk sac membrane, liver, kidney, lung, muscles, adipose tissue and plasma) were collected on d 18 of incubation and on d 21 (newly-hatched chicks) and analysed for fatty acids, vitamin E and carotenoids. 4. The diets did not differ in terms of fatty acid or alpha-tocopherol concentrations. The concentration of carotenoids in the M-diet was 11.8 mg/kg and in the W-diet was 5.6 mg/kg with lutein and zeaxanthin being major carotenoids. 5. Eggs from the M-group contained higher (P<0.01) concentrations of beta+gamma-tocopherols, total carotenoids, lutein and zeaxanthin. Chickens hatched from those eggs were characterised by the increased concentrations of total carotenoids and zeaxanthin in all the tissues studied. The concentration of beta+gamma-tocopherol was enhanced only in the liver and yolk sac membrane. 6. It is concluded that the maternal diet plays an important role in antioxidant systems formation during chick embryonic development; the M-diet can increase the antioxidant potential of the egg yolk and embryonic tissues compared to the antioxidant potential provided by parent birds fed the W-diet.  相似文献   
328.
Since 1993, 14 cases of avian influenza from four different states in the U.S.A. have been diagnosed by virus isolation from eight avian species. Only 11 of the 14 avian influenza virus (AIV) primary isolations would have been successful if only the standard protocol for AIV isolation, i.e., inoculation of specific-pathogen-free embryonating chicken eggs (ECEs) by the chorioallantoic sac (CAS) route, had been followed. Primary isolation attempts were negative for AIV in three cases in which ECEs were inoculated by the CAS route; AIV could not be detected by hemagglutinating activity, agar gel immunodiffusion test or negative stain electron microscopy. However, in these three cases, primary isolations of AIV were achieved by inoculation of ECEs into either the yolk sac or onto the chorioallantoic membrane.  相似文献   
329.
Feline coronavirus genetic elements were detected by polymerase chain reaction from blood, fecal samples, and effusive fluid collected from 33 cheetahs in the U.S.A. Feline coronavirus-specific serum antibodies were also measured by indirect immunofluorescence. Ten cheetahs were positive for viral shedding by polymerase chain reaction, whereas 13 were seropositive by immunofluorescence. Results of serology did not consistently correlate with shedding of virus, and the capture antigen used for detection of feline coronavirus-specific antibodies had a significant impact on results. Testing of samples from one population over a 1-yr period indicated chronic infection in some animals. These relatively healthy carrier animals were a source of virus for contact animals. Screening programs in cheetah populations for feline coronavirus infection may be most reliable if a combination of serologic analysis and viral detection by polymerase chain reaction is used.  相似文献   
330.
Twenty of 25 horses in a well-managed Missouri boarding stable were diagnosed with gingivitis/stomatitis. Gross examination of the affected horses revealed varying degrees of gingivitis ranging from mild periodontal swelling to marked swelling and erythema with ulceration and hemorrhage. Fine hair-like material was embedded within the intensely affected areas. Gingival biopsies from 4 affected horses contained pyogranulomatous inflammation with, in some cases, numerous eosinophils and several grass awns in cross and longitudinal section. Numerous foxtail seed heads were identified in hay samples. Examination of the records revealed that all of the affected horses had been fed the suspect hay, with the exception of 1 horse. Although not deliberately fed the suspect hay, this horse did have access to the hay when turned out into the exercise paddock. The lesions resolved following a change in hay source.  相似文献   
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