INFECTION RATES AND OUTBREAKS OF DISEASE DUE TO BABESIA ARGENTINA IN UNVACCINATED CATTLE ON 5 BEEF PROPERTIES IN SOUTH-EASTERN QUEENSLAND     

L. L. Callow  B.V.Sc.  Ph.D.  F. R. Emmerson  Q.D.A.H.†  R. J. Parker  A.I.M.L.T. S. G. Knott  B.V.Sc.  Dip. Agr. Ext.† 《Australian veterinary journal》1976,52(10):446-450

Serums from unvaccinated groups in 5 herds of beef-cattle in South-East Queensland were tested for antibodies to Babesia argentina at intervals while the cattle were increasing in age from about 6 months. An indirect fluorescent antibody test was used. Infection rates, indicating the proportions of the groups that had been exposed to tick-transmitted infection were 49.2, 56.9 and 69.1% for cattle aged approximately 6, 12 and 18 months, respectively. The degree to which cattle were infested with the vector, Boophilus microplus, was estimated. There appeared to be a strong correlation between infection rate and tick incidence. Four serologically negative animals died of either confirmed or suspected babesiosis during the sampling period. Sickness was observed in 5 others. The serological status of 57 changes from negative to positive without symptoms being observed, indicating relatively low mortality and morbidity rates in the enzootic situation studied.  相似文献   

Feed efficiency and body composition are related to cortisol response to adrenocorticotropin hormone and insulin-induced hypoglycemia in rams     

S.A. Knott  L.J. Cummins  F.R. Dunshea  B.J. Leury 《Domestic animal endocrinology》2010

Metabolic rate and energy consumption increase through the activation of the hypothalamic-pituitary-adrenal axis when an animal is exposed to a stressor. Residual feed intake (RFI) as a measure of efficiency has been shown to be related to exogenous adrenocorticotropin hormone (ACTH)-stimulated cortisol concentrations, which is indicative of the relationship between an animal's response to stress and the efficiency with which the energy is used for growth and production. In this study, we tested the hypothesis that sheep with low post-ACTH serum cortisol concentration relative to the other sheep in the flock have lower RFI values and lower cortisol concentrations following insulin-induced hypoglycemia. Adrenocorticotropin hormone (2.0 μg/kg body weight)-stimulated cortisol concentrations were measured in 100 sheep. The extreme responders were selected (n = 12 high cortisol, n = 12 low cortisol), and feed efficiency and body composition parameters were measured. A second ACTH challenge and an insulin challenge were administered. More efficient sheep (more negative RFI value) were found to have lower (P < 0.05) cortisol concentrations following both an ACTH challenge and an insulin challenge. Low-cortisol sheep (low response to ACTH or insulin) were found to have a lower (P < 0.05) proportion of fat tissue in comparison to the high-cortisol animals. These data clearly indicate that an animal's response to exogenous ACTH or insulin-induced hypoglycemia as a stressor is related (P < 0.05) to efficiency of energy use when measured as RFI. These data have important implications in enabling identification of animals that are superior in terms of feed efficiency and for understanding the physiological mechanisms underlying efficiency of energy use.  相似文献   

Use of Vaginal Electrical Resistance to Diagnose Oestrus,Dioestrus and Early Pregnancy in Synchronized Tropically Adapted Beef Heifers     

CD Hockey  ST Norman  JM Morton  D Boothby  NJ Phillips  MR McGowan 《Reproduction in domestic animals》2010,45(4):629-636

The primary objective of this study was to determine whether a single measurement of intravaginal electrical resistance (VER), using the commercially available Ovatec^® probe, can discriminate between dioestrus and oestrus in Bos indicus females, which had been treated to synchronize oestrus. Santa Gertrudis heifers (n = 226) received one of three oestrous synchronization treatments: double PGF_2α 10 days apart, 8‐day controlled internal drug release (CIDR) treatment or CIDR pre‐synchronization + PGF_2α 10 days after CIDR removal. The heifers were inseminated within 12 h following observed oestrus, or, if not observed, at a fixed time approximately 80 h, following the last synchronization treatment. They were palpated per rectum for signs of pregnancy 9 weeks after artificial insemination (AI). Vaginal electrical resistance measurements were taken at the completion of synchronization treatments (presumed dioestrus), immediately prior to AI (oestrus), and then at 3 and 9 weeks post‐AI. Mean VER differed between presumed dioestrus and oestrus (113.7 vs 87.4, p < 0.001). The area under the receiver operating characteristics (ROC) curve was 0.925, indicating that VER was highly discriminatory between dioestrus and oestrus. Vaginal electrical resistance at time of AI was negatively associated with odds of conception when all inseminations were included in the analyses [odds ratio (OR) = 0.97; 95% CI 0.95–1.00; p = 0.018], but not when fixed time AIs were excluded (OR = 1.00; 95% CI 0.97–1.03; p = 0.982). Mean VER readings differed between pregnant and non‐pregnant animals at both 3 weeks (120.5 vs 96.7, p < 0.001) and 9 weeks (124.0 vs 100.3, p < 0.001) post‐AI. However, 3‐ and 9‐week VER measurements were not highly discriminatory between pregnancy and non‐pregnancy (area under ROC curve = 0.791 and 0.736, respectively). Mean VER at time of AI for animals diagnosed in oestrus differed between each of the oestrous synchronization treatments (84.7, 73.6 and 78.9, groups 1–3 respectively, p < 0.001). These findings suggest that measurement of VER may improve accuracy of oestrus diagnoses when selecting cattle for AI following oestrous synchronization programmes involving tropically adapted cattle.  相似文献   

Pulmonary adiaspiromycosis in critically endangered northern hairy‐nosed wombats (Lasiorhinus krefftii)          下载免费PDF全文

AB Schaffer‐White  D Harper  M Mayhew  A McKinnon  L Knott  RE Allavena 《Australian veterinary journal》2017,95(11):431-436

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Ovine Johne's disease: the risk associated with sheep imported into Western Australia     

ARB HIGGS  CD HAWKINS 《Australian veterinary journal》1998,76(8):546-550

Objective To assess the risk of Johne's disease not being detected in sheep imported from New South Wales into Western Australia.
Design A stochastic simulation model.
Procedure The process of importing sheep was broken down into steps and numbers or probabilities assigned to each. Controls on the movement of sheep included surveillance tests in source flocks and serological tests on sheep in consignments before and after transportation to Western Australia. The model calculated the risk of occurrence of Johne's disease in Western Australia and the success of the agar gel immunodiffusion test in identifying consignments with infected sheep.
Results Negative surveillance tests in source flocks reduced the risk to about one twentieth of that when no surveillance tests were required. On average, Johne's disease was predicted to be introduced once in every 3 to 7 years when no testing of either the source flock or the sheep in consignments was required. When negative surveillance tests only were required the interval increased to once in every 63 to 111 years and, with the additional requirement that all sheep in each consignment must have a negative test before and after transport, the interval further increased to once in every 125 to 333 years. When only sheep in consignments were tested, the interval was calculated to be 8 to 14 years.
Conclusion A requirement that imports be derived from flocks which had negative surveillance tests to Johne's disease would provide significantly greater protection for the sheep industry in Western Australia.  相似文献   

Size and age are important factors for marine sanctuaries: evidence from a decade of systematic sampling in a subtropical marine park          下载免费PDF全文

Hamish A. Malcolm  Alan Jordan  Robert G. Creese  Nathan A. Knott 《水产资源保护:海洋与淡水生态系统》2016,26(6):1090-1106

Diagnosis and surgical treatment of thyroid adenoma-induced hyperthyroidism in a green iguana (Iguana iguana).     

S J Hernandez-Divers  C D Knott  J MacDonald 《Journal of zoo and wildlife medicine》2001,32(4):465-475

An adult female green iguana (Iguana iguana) presented with polyphagia, loss of the dorsal spines, hyperactivity, increased aggression, tachycardia, and a bilobate mass palpable anterior to the thoracic inlet. Diagnosis of hyperthyroidism was based on a total T4 (30.0 nmol/L) elevated above that of clinically healthy iguanas (3.81 +/- 0.84 nmol/L), and histopathology confirmed a functional thyroid adenoma. Surgical thyroidectomy safely returned the lizard to a euthyroid state.  相似文献   

Evaluation of a Neck Mounted 2‐Hourly Activity Meter System for Detecting Cows About to Ovulate in Two Paddock‐Based Australian Dairy Herds     

CD Hockey  JM Morton  ST Norman  MR McGowan 《Reproduction in domestic animals》2010,45(5):e107-e117

Two studies were conducted to assess the performance of a commercially available neck‐mounted activity meter to detect cows about to ovulate in two paddock‐based Holstein‐Friesian dairy herds. The activity monitoring system recorded cow activity count in 2‐hourly periods. Study I investigated the ability of the system to detect cow ovulatory periods in dairy herds managed in two different Australian environments and breeding systems using five activity alert algorithms. Herd 1 consisted of approximately 130 milking cows calving year‐round in a sub‐tropical environment and kept in a single dry lot paddock. Herd 2 consisted of approximately 400 milking cows calving seasonally in a temperate climate and fed pasture by rotation through multiple grazing paddocks. Ovulatory periods and non‐ovulatory days were identified using milk progesterone monitoring alone or in combination with ovarian ultrasonography; using these ‘gold standards’ 141 and 135 ovulatory periods were identified in 64 and 135 cows in Herds 1 and 2 respectively. Sensitivity of the activity monitoring system for detecting cow ovulatory periods ranged from 79.4% to 94.1%, specificity from 90.0% to 98.2% and positive predictive value from 35.8% to 75.8%. Study II investigated the ability of the activity meter system to predict the timing of ovulations in paddock‐based pasture‐fed dairy cattle (Herd 2). The time of ovulation was estimated by repeat trans‐rectal ovarian ultrasonography at approximately 0, 12, 24 and 36 h after artificial insemination (AI). The mean times (±SD) from onset and end of increased activity to ovulation were 33.4 ± 12.4 and 17.3 ± 12.8 h respectively (n = 94). Fifty per cent of cows (n = 47) ovulated within the 8‐h period between 30 to 38 hs after the onset of increased activity, 76.6% (n = 72) within the 16 h between 24 to 40 h, 85.1% (n = 80) within the 24 h between 18 and 42 h and 90.4% (n = 85) within the 32 h from 19 to 51 h after the onset of increased activity. Results from these studies show that in paddock‐based dairy cows in two diverse management systems, this neck‐mounted activity meter system detects high proportions of cows that are about to ovulate and provides a useful indication of when ovulation is likely to occur. However, the specificities and positive predictive values using the algorithms assessed may be lower than desirable.  相似文献   

Oximetry Fails to Predict Acute Mountain Sickness or Summit Success During a Rapid Ascent to 5640 Meters     

Dale R. Wagner  Jonathan R. Knott  Jack P. Fry 《The Forestry Chronicle》2012,23(2):114-121

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VACCINATION WITH BABESIA ARGENTINA IN 5 BEEF HERDS IN SOUTH-EASTERN QUEENSLAND     

F. R. Emmerson>  Q.D.A.H.  S. G. Knott  B.V.Sc.  D.A.E. L. L. Callow  B.V.Sc.  Ph.D.† 《Australian veterinary journal》1976,52(10):451-454

Observations on the use of a vaccine containing Babesia argentina in 5 partly susceptible beef herds in south-eastern Queensland were made on 1,029 female breeding cattle over a period of 4 years. Groups averaging about 20 heifers were given 0, 1, 2 or 3 vaccinations. Incidence derived from groups experiencing clinical attacks were 17.9% for unvaccinated cattle and 1.2% for vaccinates. Increasing the number of vaccinations did not appear to increase protection. The one clinical manifestation of infection with B. bigemina was associated with a concurrent reaction to vaccination with Anaplasma centrale. There were no cases of haemolytic anaemia in new-born calves. No severe reactions followed primary vaccination, but 2 revaccinated animals became sick.  相似文献