The influence of nitrogen status on the susceptibility of segments of cereal leaves to paraquat     

P. J. W. LUTMAN  C. R. SAGAR  C. MARSHALL  D. W. R. HEADFORD † 《Weed Research》1975,15(2):89-92

Segments (2·5 cm long) taken from the third leaf of young barley (Hordeum vulgare L.) and oat (Arena sativa L.) plants growing at low nitrogen levels were found to be more susceptible to a 0·01 ml droplet of paraquat solution placed on the adaxial surface, than segments taken from leaves of plants grown at higher nitrogen levels. Similar relative differences in susceptibility were found between leaf segments infiltrated with paraquat. Tolerance of leaf segments to paraquat increased as the leaves expanded but there was no significant increase in tolerance with increasing age after expansion was complete. The influence of nitrogen on the structure and physiology of leaves is discussed and the results are compared with earlier experiments where whole plants sprayed with paraquat were found to be less susceptible when grown at the low nitrogen level. Influence de l'azote sur la sensibilité des fragments de feuilles de céréles au paraquat Des fragments de 2,5 cm de long prélevés sur la troisième feuille de jeunes plantes d'orge (Hordeum vulgare L.) et d'avoine(Avena sativa L.) cultivées à de faibles niveaux d'azote ont été plus sensibles à une gouttelette de 0,01 ml d'une solution de paraquat, placée sur la surface adaxiale, que des fragments prélevés sur des feuillcs de plantes cultivées k des niveaux d'azote plus élcvés. Des différences relatives analogues dans la sensibility ont été constantées entre des fragments de feuilles infiltrés uvec du paraquat. La résistance dc fragments de feuilles au paraquat s'accrut lorsque les feuilles se développèrent mais il n'y eut pas d'accroissement significatif de la résistance avec l'accroissement de l'age. après que l'expansion füt complète. L'influence de l'azote sur la structure et la physiologic des feuilles est discutée et les résultats sont comparés avec des expériences antérieures dans lesquelles des plantes traitées entièrement avec du puniquat se montrèrent moins sensibles lorsqu'elles étaient cultivées à un faible niveau d'aZOtte. Der Einflu β der Sticksloffversorgung auf die Empfindlichkeit von Getreideblattabschnitten gegen Paraquat Es wurde gefunden, da β 2·5 cm lange Abschnitte vom dritten Blatt junger Gersten- (Hordeum vulgare L.) und Haferpflanzen (Avena saliva L.). die bei niedrigem Stickstoffniveau aufwuchsen, gegen einen auf die adaxiale Oberfläche aufgebrachten kleinen Tropfen (0·01 ml) einer Paraquallösung empfindlicher waren ah Abschnitte von Blättern solcher Pflanzen, die bei höheren Stickstoffgehalten aufgewachsen waren. Im Verhältnis zucinander ähnliche Unterschiede in der Empfindlichkeit wurden zwischen Blattabschnitten gefunden, die mit Paraquat infiltriert waren. Die Toleranzder Blattabschnitte gegenüber Paraquat nahm mil dem Wachstum der Blatter zu; nach abgeschlossenem Wachstun war mit zunehmendem Alter jedoch eine signifikante Zunahme der Toleranz nicht zu Verzeichnen. Es wird der Einflu β von Stickstoff auf die Struktur und Physiologie von Blättern besprochen; die Ergebnisse werden mit früheren Ergebnissen verglichen, bei denen sich gezeigt hatte, da β mit Paraquat gespritzte ganze Pflanzen weniger empfindlich waren, wenn sie bei niedrigem Stickstoffniveau gewachsen waren.  相似文献   

Effects of Exogenous Tumour Necrosis Factor-α on the Secretory Function of the Bovine Reproductive Tract Depend on Tumour Necrosis Factor-α Concentrations     

DJ Skarzynski  KK Piotrowska  MM Bah  A Korzekwa  I Woclawek-Potocka  K Sawai  K Okuda 《Reproduction in domestic animals》2009,44(3):371-379

The aim of study was to correlate tumour necrosis factor-α (TNF) infused doses used with the TNF concentrations achieved and with the secretory function of both the ovary and the uterus in cows. We evaluated the concentrations of progesterone (P4), prostaglandin (PG)F_2α, PGE₂ nitric oxide (NO) and TNF in the jugular vein and vena cava caudalis as parameters of exogenous TNF action on the female reproductive tract. Aortae abdominalis of cows (n = 18) were infused with saline or two doses of TNF (luteolytic – 1 μg or luteotrophic – 10 μg). In the peripheral blood, 1 μg TNF concentrations achieved within the range of 30–45 pg/ml, and 10 μg TNF provoked a sharp increase in achieved concentrations at a range of 250–450 pg/mL). The TNF concentrations achieved in vena cava caudalis were five to six times higher than that in peripheral blood (p < 0.001). One microgram TNF increased PGF_2α and NO (p < 0.001) and decreased P4 (p < 0.05). The higher TNF dose stimulated P4 and PGE₂ (p < 0.01). TNF infusion at luteolytic dose achieved its concentrations at the physiological range previously observed in cows. Luteotrophic TNF dose achieved the concentrations in vena cava caudalis that are much higher than physiological level and were previously noted in pathological circumstances (i.e. mastitis , metritis ).  相似文献   

Effect of eCG or eCG Plus hCG on Oestrus Expression and Ovulation in Prepubertal Gilts     

R Manjarin  G Cassar  DJ Sprecher  RM Friendship  JC Dominguez  RN Kirkwood 《Reproduction in domestic animals》2009,44(3):411-413

To meet weekly breeding targets, it is occasionally necessary to inject exogenous gonadotrophins to induce oestrus in prepubertal gilts. However, the gilt oestrus response to equine chorionic gonadotrophin (eCG) either alone or in combination with human chorionic gonadotrophin (hCG) can be unpredictable. The objective of the present study was to examine possible reasons for this unpredictability. Prepubertal gilts (90 kg and 153 days of age, n = 109) received an injection of either 600 IU eCG or a combination of 400 IU eCG and 200 IU hCG (PG600), or were non-injected controls, and were then exposed to a mature boar for 15 min daily for 7 days for oestrus detection. At the time of injection, real-time ultrasound revealed that the gilt ovaries had primarily 1–2 mm follicles. Blood samples were obtained at time of hormone injection (day 0) and at days 3, 7 and 10 for assay of serum progesterone concentrations. The oestrus responses by 7 days were15.5%, 73.3% and 0%, for eCG, PG600, and control gilts, respectively (p < 0.001). The oestrus response improved (p < 0.05) with increasing body weight. Based on circulating progesterone levels, all oestrous gilts ovulated except for four of the PG600 gilts. Failure to express oestrus in PG600 gilts was not associated with a premature rise in progesterone.  相似文献   

Spinal dermoid sinus in a Burmese cat with paraparesis   总被引：1，自引：1，他引：0  

T Tong  DJ Simpson 《Australian veterinary journal》2009,87(11):450-454

A 2-year-old, male, Burmese cat was evaluated for chronic progressive hindlimb weakness, ataxia and urinary incontinence. Radiographic examination, myelography and magnetic resonance imaging defined congenital vertebral anomalies and a space-occupying intradural, extramedullary mass. A dermoid sinus was subsequently identified dorsal to the affected spine. Surgical excision of the tract necessitated a dorsal laminectomy and removal of a 1-cm diameter intradural dermoid sinus 'cyst' that contained hair and sebaceous debris. The cat recovered hindlimb function after surgery and remains asymptomatic 50 months after surgery except for a persistent inability to urinate voluntarily.  相似文献   

Antimicrobial use in the Australian pig industry: results of a national survey   总被引：1，自引：1，他引：0  

D Jordan  JJ-C Chin  VA Fahy  MD Barton  MG Smith  DJ Trott 《Australian veterinary journal》2009,87(6):222-229

Objective   To describe how various antimicrobials are used in commercial pig herds in Australia and for what disease conditions.
Procedure   Managers of large pig herds (> 200 sows) across Australia and their veterinarians participated in an internet-based survey in 2006. Questions were asked about herd management, the occurrence of bacterial diseases and the type and frequency of antimicrobial use. An antimicrobial usage index for each herd was derived as a summary of the risk of selection for antimicrobial resistance. Relationships between responses were explored with univariate and multivariate analysis.
Results   Responses were received for 197 herds estimated to represent at least 51% of all large pig herds in Australia. Most piggeries relied on drugs of low importance in human medicine (e.g. tetracyclines, penicillins and sulfonamides). For the two drugs of high importance in human medicine that can be legally prescribed to pigs in Australia, ceftiofur use was reported in 25% of herds and virginiamycin in none. Infections attributed to Lawsonia , Mycoplasma and Escherichia coli motivated the most use of antimicrobials. No useful association was found between management factors and the antimicrobial use index.
Conclusion   Most antimicrobial use in the Australian pig industry is based on drugs of low importance to public health. Enhanced control of E. coli infections without reliance on antimicrobials would further reduce the risk of selecting for antimicrobial resistance relevant to public health. The amount of variation in the usage index between herds suggests that antimicrobial use should be constantly reviewed on a herd by herd basis.  相似文献   

Integrating practical, regulatory and ethical strategies for enhancing farm animal welfare     

DJ MELLOR  KJ STAFFORD 《Australian veterinary journal》2001,79(11):762-768

OBJECTIVE: To provide an integrated view of relationships between assessment of animal welfare. societal expectations regarding animal welfare standards, the need for regulation, and two ethical strategies for promoting animal welfare, emphasising farm animals. APPROACH: Ideas in relevant papers and key insights were outlined and illustrated, where appropriate, by New Zealand experience with different facets of the welfare management of farm animals. CONCLUSIONS: An animal's welfare is good when its nutritional, environmental, health, behavioural and mental needs are met. Compromise may occur in one or more of these areas and is assessed by scientifically-informed best judgement using parameters validated by directed research and objective analysis in clinical and practical settings. There is a wide range of perceptions of what constitutes good and bad welfare in society, so that animal welfare standards cannot be left to individual preferences to determine. Rather, the promotion of animal welfare is seen as requiring central regulation, but managed in a way that allows for adjustments based on new scientific knowledge of animals' needs and changing societal perceptions of what is acceptable and unacceptable treatment of animals. Concepts of 'minimal welfare', representing the threshold of cruelty, and 'acceptable welfare', representing higher, more acceptable standards than those that merely avoid cruelty, are outlined. They are relevant to economic analyses, which deal with determinants of animal welfare standards based on financial costs and the desire of the public to feel broadly comfortable about the treatment of the animals that are used to serve their needs. Ethical strategies for promoting animal welfare can be divided broadly into the 'gold standard' approach and the 'incremental improvement' approach. The first defines the ideal that is to be required in a particular situation and will accept nothing less than that ideal, whereas the second aims to improve welfare in a step-wise fashion by setting a series of achievable goals, seeing each small advance as worthwhile progress towards the same ideal. 'Incremental improvement' is preferred. This also has application in veterinary practice where the professional commitment to maintain good welfare standards may at times conflict with financial constraints experienced by clients.  相似文献   

Failure of a single postpartum prostaglandin treatment to improve the reproductive performance of dairy cows     

JM MORTON  JD ALLEN†  DJ HARRIS‡  GT MILLER§ 《Australian veterinary journal》1992,69(7):158-160

A study was conducted to evaluate the effects of postpartum prostaglandin treatment on reproduction in 3 seasonal calving dairy herds. Recently calved lactating dairy cows were paired on herd, age, calving date and previous production index. One cow in each of the 196 pairs received a single intramuscular injection of 25 mg of the prostaglandin analogue, dinoprost, between 14 and 28 days after calving. Subsequent reproduction was monitored. Within each herd and overall, there was no significant effect of treatment on the intervals from calving to first service, mating start date to first service, calving to conception, mating start date to conception and first service to conception. Treatment also had no significant effect on 21-day submission and pregnancy rates, on the proportion of each group not pregnant at the end of mating, and on first service pregnancy rates. Responses to treatment did not vary between cows calving within 50 days of mating start date and earlier calving cows or between cows aged less than 5 years and older cows.  相似文献   

A molecular genetic assessment of herbicide-resistant Sinapis arvensis   总被引：1，自引：0，他引：1  

MEIKLE  FINCH  McROBERTS  & MARSHALL 《Weed Research》1999,39(2):149-158

The acquisition of resistance to both the auxinic herbicide dicamba and the sulfonylurea herbicide chlorsulfuron has been recorded in Canadian populations of the weed species Sinapis arvensis L. (charlock, wild mustard) To study the effect of this selection for herbicide resistance on levels of genetic variation, polymerase chain reaction-based DNA fingerprinting techniques were used to characterize two herbicide-resistant and one susceptible population of S. arvensis . Analysis of the resultant DNA marker profiles revealed extensive polymorphism between individuals. However, segregation of the three biotypes was detectable despite high levels of intrabiotype polymorphism. No reduction in the levels of heterozygosity within the resistant populations were found compared with the susceptible population.  相似文献   

The distribution and prevalence of Theileria buffeli in cattle in Queensland     

NP STEWART  NF STANDFAST†  FC BALDOCK‡  DJ REID  AJ de  VOS† 《Australian veterinary journal》1992,69(3):59-61

The distribution and prevalence of Thelleria buffeli in Queensland cattle were investigated using serum samples and blood films collected primarily for brucellosis surveillance and tick fever diagnosis. Serums from 8654 cattle from 357 farms throughout Queensland were examined by an indirect fluorescent antibody test for antibody to T buffeli. In addition, 347 peripheral blood films collected from 147 farms in south-eastern Queensland were examined for piroplasms of T buffeli. The overall herd and animal prevalences for T buffeli were 75% and 41%, respectively. There was significant variation among regions in both herd and animal prevalences (P less than 0.001). Herd and animal prevalences were highest in the north and east decreasing westward. The results indicate that T buffeli is more widespread in Queensland than previously thought.  相似文献   

Confocal microscopy of the antigen-antibody reaction site in nematode larvae     

DJ MCGILLIVERY  RE MORTON  WK YONG  GG RIFFKIN  C. JOHNSON  B. ADLER 《Australian veterinary journal》1992,69(2):41-42

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