Effects of seed depth and soil aggregates on the emergence of weeds with contrasting seed traits     

A GARDARIN  C DÜRR  N COLBACH 《Weed Research》2010,50(2):91-101

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Continuous disinfection as a means to control infectious diseases in poultry. Evaluation of a continuous disinfection programme for broilers     

Bragg RR  Plumstead P 《The Onderstepoort journal of veterinary research》2003,70(3):219-229

A full continuous disinfection programme, consisting of disinfection during cleanout of poultry houses prior to placement of chickens, disinfection of the drinking water and spray disinfection of the birds during production was evaluated in broilers under experimental condition as well as under field conditions. Under controlled conditions, the experimental design consisted of three groups, two of which were control groups. Each group comprised 300 chickens. In one of the control groups, no disinfection of the pens was undertaken prior to the placement of the chickens. In the other control group, disinfection of the pens prior to placement of the birds was carried out using a glutaraldehyde-based product. In the test group, disinfection prior to placement was done. The drinking water of these birds was treated continuously and the birds were sprayed with a non-toxic disinfectant during production. Production parameters, such as growth rate, feed conversion ratio and feed consumption, of the birds in the three groups were monitored. In addition, all mortalities in the different groups were recorded and classified into diseases of an infectious nature, non-infectious nature and unknown category. Bacterial counts were also done on a weekly basis from the different pens. In this experiment, it was shown that the full continuous disinfection programme resulted in a lower number of mortalities caused by infectious agents as well as a reduction in the bacterial counts in the pens treated with the full continual disinfection programme. The full continuous disinfection programme was also tested on a commercial poultry farm in the Northern Cape Province of South Africa. Two production houses of 3,500 birds were randomly selected as test houses for the full continuous disinfection programme. Another similar house, which received day-old chicks from the same batch as the other two houses, was selected as the control house; it received the routine disinfection procedure prior to placement of the chicks. During the course of this experiment, a severe outbreak of Newcastle disease was experienced on this farm. It was demonstrated that, in the face of this severe challenge, the full continuous disinfection programme controlled the spread of the disease in both the houses where it had been applied at a stage when in every other house (including the control house) on the farm birds were suffering very high mortalities.  相似文献   

Mycobacterium fortuitum isolated from three species of fish in South Africa     

R R Bragg  H F Huchzermeyer  M A Hanisch 《The Onderstepoort journal of veterinary research》1990,57(1):101-102

Mycobacterium fortuitum was isolated from 3 species of freshwater fish in South Africa for the first time. The bacterium was isolated from oscars, guppies and discus fish from different sources. Heavy mortalities as a result of infection with this bacterium were reported from a guppy farm and the multi-resistance of this isolate to antimicrobials rules out the treatment of infected fish.  相似文献   

Health status of salmonids in river systems in Natal. II. Isolation and identification of viruses     

R R Bragg 《The Onderstepoort journal of veterinary research》1991,58(2):63-65

A total of 678 fish from 26 different sites along 8 river systems was examined for the presence of trout viruses. No isolations of any viruses were made from any fish collected from these systems in Natal during this study. No antibodies against any of the trout viruses were detected in the serum collected from these fish. It would appear from this study that the river systems in Natal are free of any of the known viruses of trout. Infectious pancreatic necrosis virus was, however, isolated from trout from the Natal Parks Board Hatchery at Kamberg Nature Reserve on the Mooi River during June and July of 1988. Neutralising antibodies against the VR 299 serotype of IPN virus were detected in the serum collected from trout at Kamberg in September 1988.  相似文献   

British Achievements in X-ray Crystallography     

Bragg WL 《Science (New York, N.Y.)》1960,131(3417):1870-1874

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Isolation and identification of adenovirus 127, the causative agent of egg drop syndrome (EDS), from commercial laying hens in South Africa.     

R R Bragg  D M Allwright  L Coetzee 《The Onderstepoort journal of veterinary research》1991,58(4):309-310

A drop in egg production associated with loss of pigment and soft-shelled eggs was experienced on a farm in the Western Cape. Investigations revealed high levels of antibodies against adenovirus 127, the causative agent of egg drop syndrome (EDS) in chickens which were not vaccinated against EDS. A cytopathic agent was subsequently isolated in chicken embryo liver cell cultures and identified as EDS virus by haemagglutination inhibition and neutralization tests.  相似文献   

Deficiency of uridine monophosphate synthase in Holstein cattle: inheritance and body measurements   总被引：2，自引：0，他引：2  

R D Shanks  D S Bragg  J L Robinson 《Journal of animal science》1987,64(3):695-700

Blood samples and body measurements were obtained from daughters of seven Holstein bulls previously shown to have a partial deficiency of uridine monophosphate (UMP) synthase and presumed to be heterozygous for the condition. Erythrocyte UMP synthase for 85 daughters showed a bimodal distribution with 42 having half the normal activity of 43 others. Furthermore, each bull had 50% of his daughters represented in each group, a finding fully consistent with the heterozygous designation of these bulls. Because UMP synthase is needed for pyrimidine biosynthesis and hence DNA and RNA metabolism, it was hypothesized that a partial deficiency could result in slower growth and smaller size for affected animals. Body measurements, as estimates of growth and size, included body length, wither height, hip height, hip width, rump length, pin width and taped body weight. Although measurements varied by age, differences between normal and heterozygous females were not found. One-half the normal activity of UMP synthase in cattle was adequate for near normal growth. Additionally, herd life was not significantly affected in heterozygous females.  相似文献   

Isolation of serovar C-3 Haemophilus paragallinarum from Zimbabwe: A further indication of the need for the production of vaccines against infectious coryza containing local isolates of H. paragallinarum     

Bragg RR 《The Onderstepoort journal of veterinary research》2002,69(2):129-132

Various isolates of Haemophilus paragallinarum, collected from a severe outbreak of infectious coryza in poultry from Zimbabwe, were serotyped and were found to belong to serovar C-3. Previously, isolates were serotyped using polyclonal antiserum produced against serogroup reference strains (0083 for serogroup A, 0222 for serogroup B and Modesto, or H-18 for serogroup C) of H. paragallinarum. In this case, polyclonal antiserum produced against these reference isolates were used, as well as polyclonal antiserum that has been raised specifically against the serovar C-3 isolate 46 C-3. When using the latter serum at a 1 in 50 dilution, no cross-reaction with other members of serogroup C were found. The severity of the disease outbreak in Zimbabwe, the vaccination history of the infected flocks on the sites and the isolation of the uniquely southern African serovar C-3, further highlights the need for vaccines composed of local isolates to control infectious coryza in regions where vaccination failures occur.  相似文献   

Virulence of South African isolates of Haemophilus paragallinarum. Part 2: naturally occurring NAD-independent field isolates     

Bragg RR 《The Onderstepoort journal of veterinary research》2002,69(2):171-175

Naturally occurring NAD-independent variants of Haemophilus paragallinarum, which have been isolates from poultry showing clinical signs of infectious coryza, were used to determine their virulence using a newly developed challenge model for infectious coryza. It was established that the NAD-independent isolates belonging to a particular serogroup, were less virulent when compared to the virulence of the NAD-dependent isolates from the same serogroup. It was shown that the virulence of the NAD-independent isolates belonging to serogroup C and serogroup A were very similar to each other. This differs to the results obtained with NAD-dependent isolates reported on previously, in which the serogroup C isolates were found to be more virulent then the serogroup A isolates.  相似文献   

The leech Batracobdelloides tricarinata (Blanchard, 1897) (Hirudinea: Glossiphoniidae) as a possible reservoir of the rainbow trout pathogenic Streptococcus species     

R R Bragg  J H Oosthuizen  S M Lordan 《The Onderstepoort journal of veterinary research》1989,56(3):203-204

A Streptococcus species biochemically and serologically identical to the rainbow trout pathogenic Streptococcus species was isolated from the internal organs of the fish specific leech, Batracobdelloides tricarinata. These leeches were obtained from Roodeplaat Dam, near Pretoria, in which rainbow trout do not occur. This is the first isolation of this bacterium from an environmental source not related to rainbow trout and it is proposed that this leech is a possible reservoir of the rainbow trout pathogenic Streptococcus sp. in South Africa.  相似文献