Anthelmintic resistance and management of nematode parasites on beef cattle-rearing farms in the North Island of New Zealand     

R Jackson  AP Rhodes  WE Pomroy  DM Leathwick  DM West  TS Waghorn 《New Zealand veterinary journal》2013,61(6):289-296

AIM: To provide information on current farmers’ opinions and farming practices thought to be related to anthelmintic resistance, and to test for associations between the presence of anthelmintic resistance and management practices on beef cattle- rearing farms in the North Island of New Zealand.

METHODS: A study using an interview-based questionnaire about management of internal parasites was conducted on 62 beef cattle-rearing farms in the North Island of New Zealand, using case-control analyses to test for associations between management practices and the presence or absence of resistance to ivermectin or albendazole. Resistance was inferred from faecal nematode egg count (FEC) reduction (FECR) tests (FECRTs) when there was <90% reduction in FEC 7-10 days after treatment of calves <12 months of age.

RESULTS: Of the 59 farmers who completed the questionnaire, most (n=40) ranked parasites highly, and at about the same level as quality and quantity of feed, as important production-limiting factors for their enterprises. In contrast, anthelmintic resistance was not perceived to be a problem on 13 farms, and its importance was rated low on 24, moderate on 15, and high on only six farms. Despite all farms having planned parasite control programmes, there was heavy reliance on clinical signs of parasitism to determine frequency of treatments. About one in three farmers with beef breeder cows routinely treated their calves at marking, one in five treated mixed-age cows, and almost half treated rising 2-year-old cows before calving. One in four farmers used anthelmintics on calves on 8–12 occasions in their first year of life. Co-grazing with other species was rare, but follow-on grazing within 3 months after older cattle or sheep was common. On most farms, grazing cattle was restricted to part of the farm, a finding with implications for parasite control and persistence of larvae in refugia. Macrocyclic lactone (ML) anthelmintics or their combinations with other action families were currently, and for the past 5 years, used more frequently than benzimidazoles and levamisole, and benzimidazole-levami- sole combinations. The prevalence of resistance to ivermectin was high (82%) and no plausible model of associations could be constructed from the data. The prevalence of resistance to albendazole was 60%, and the risk of resistance increased as the number of rising 1-year-old cattle present mid-winter increased, and decreased as the number of breeding cows >2 years old present mid-winter increased.

CONCLUSION: It is clear that in practice anthelmintic resistance is a secondary consideration to obtaining productivity advantages from the use of anthelmintics in beef cattle. Farmers’ opinions were divided on many issues and the overall impres- sion was of confused and diverse thinking regarding the principles of the use of anthelmintics. The overall outlook regarding anthelmintic resistance in cattle is bleak unless the need for integrated and long-term research activities is acted upon soon.  相似文献   

长江口沿岸碎波带刀鲚仔稚鱼的数量分布   总被引：9，自引：3，他引：6  

葛珂珂  钟俊生  吴美琴  赵盛龙  张冬良 《中国水产科学》2009,6(6)

2007年5-10月,每月大潮期间在长江口沿岸碎波带13个站位用小型拖网各采样1次.195次拖网共采获刀鲚(Coilia nasus)仔稚鱼9 358尾,体长范围为3.0～61.2mm,优势体长为6.0～25.0 mm,以10.0～16.0 mm的弯曲期和13.0～21.0 mm的后弯曲期仔鱼为主.采获数量以7月最高,占总数55.0%,主要分布在长江口南支和北支上游,有3个站位(St.5、St.7、St.10)数量较高.其中有1个站位(St.7)刀鲚仔鱼的平均体长按月呈递增趋势,表明刀鲚仔稚鱼有利用沿岸碎波带作为早期生长场所的习性.根据刀鲚仔稚鱼在长江口沿岸碎波带分布和数量变动的调查结果,结合目前刀鲚成鱼资源量贫乏的现状,建议有关部门限制鳗苗定置网等作业,并加强对沿岸碎波带保育场的保护.  相似文献   

宫内生长迟缓仔猪T细胞的发育研究   总被引：1，自引：1，他引：0  

林燕  王军军  王晓秋  吴伟宗  赖长华 《中国畜牧杂志》2009,45(21)

研究旨在探讨从出生到断奶不同日龄宫内生长迟缓(IUGR)猪T细胞的发育变化情况。选用体重相近和配种期相同的达兰初产妊娠母猪30头,分娩时从每窝仔猪中挑选1头正常体重猪和1头IUGR猪,分别在1、7、14、21、28日龄时屠宰取胸腺,分离T细胞,通过流式细胞仪测定CD3、CD4、CD8T细胞的数量,每个日龄6个重复。结果表明:出生后第1天IUGR仔猪与正常仔猪的CD4+CD8+细胞(双阳性T细胞)占总T细胞的百分比差异显著(P<0.05);出生后第7天IUGR仔猪与正常仔猪的CD4细胞占总T细胞的百分比差异极显著(P<0.01);后期各细胞亚群之间没有差异。结果提示,子宫内各种因素的综合影响能造成出生后早期IUGR仔猪T细胞亚群发育不完善,这就从T细胞亚群的发育方面解释了IUGR仔猪免疫力低的原因。  相似文献   

Epidemiology of the epidemic of bovine anaemia associated with Theileria orientalis (Ikeda) between August 2012 and March 2014     

K Lawrence  AMJ McFadden  E Gias  DJ Pulford  WE Pomroy 《New Zealand veterinary journal》2016,64(1):38-47

AIMS: To describe the epidemiology of the epidemic of bovine anaemia associated with Theileria orientalis infection (TABA) in New Zealand between 30 August 2012 and 4 March 2014.

METHODS: Blood samples and associated data were obtained from cases of TABA. The case definition for TABA was met when piroplasms were present on blood smears and the haematocrit was ≤0.24?L/L. Samples were analysed using quantitative PCR (qPCR) assays for the detection of T. orientalis Ikeda type. Only cases that were positive in the qPCR assays were included in the analysis. A case herd was defined as a herd that had ≥1 animal positive for T. orientalis Ikeda.

Movement records for farms were accessed through the national animal identification and tracing scheme. The OR for cattle movements onto a case farm compared to a non-case farm was estimated using a generalised estimating equation model and the geodesic distance for movements onto case and non-case farms compared using Student's t-test. The kernel-smoothed risk of disease at the farm level was calculated using an extraction map and the clustering of diseased farms in time and space was measured using the spatial temporal inhomogeneous pair correlation function.

RESULTS: In the first 18 months there were 496 case herds; 392 (79%) were dairy and 104 (21%) beef herds. Of 882 individual cases, 820 (93.0%) were positive for T. orientalis Ikeda in the qPCR assays. Case herds were initially clustered in the Northland, then the Waikato regions. The OR for a case farm compared to a non-case farm having ≥1 inward cattle movements was 2.03 (95% CI=1.52–2.71) and the distance moved was 26 (95% CI=20.8–31.3) km greater for case farms. The risk of disease was highest in a north, north-eastern to south, south-western belt across the Waikato region. The spatial-temporal analysis showed significant clustering of infected herds within 20–30 days and up to 15?km distant from a case farm.

CONCLUSIONS: Theileria orientalis Ikeda type is likely to have been introduced into regions populated with naïve cattle by the movement of parasitaemic cattle from affected areas. Local spread through dispersed ticks then probably became more important for disease transmission between herds once the disease established in a new area.

CLINICAL RELEVANCE: Dairy and beef farming in the North Island of New Zealand will be significantly changed in the coming years by the incursion of this new disease.  相似文献   

Benzimidazole resistance in Nematodirus spathiger and N. filicollis in New Zealand     

AMB Oliver  WE Pomroy 《New Zealand veterinary journal》2016,64(4):201-206

AIM: To determine the prevalence of benzimidazole resistance in Nematodirus spathiger and N. filicollis from a sample of New Zealand farms.

METHODS: The efficacy of albendazole (ABZ) against Nematodirus spp. was assessed by faecal nematode egg count reduction (FECR) tests undertaken in lambs aged 3–8 months old on 27 sheep farms throughout New Zealand. On each farm, groups of 10–16 lambs were either treated with ABZ (4.75?mg/kg) or remained as untreated controls. Faecal samples were collected from all animals at the time of treatment and 7–10 days later. Faecal nematode egg counts (FEC) were performed using a modified McMaster technique. Larvae were cultured from pooled faecal samples, collected 7–10 days after treatment from each group, by incubation at 20°C for 6 weeks, 4°C for 26 weeks then 13°C for 2 weeks. The resulting third stage larvae were identified to species using a multiplex PCR assay, that identified species-specific sequences in the second internal transcribed spacer region of ribosomal DNA. The efficacy of ABZ for N. spathiger and N. filicollis was calculated from the proportion of the two species in culture and the group mean FEC before and after treatment. Only farms with a mean of 10?epg for each species in untreated samples were included for analysis. Resistance was defined as an efficacy <95%.

RESULTS: On farms that met the threshold of 10?epg in faecal samples, benzimidazole resistance was found on 20/21 (95%) farms for N. spathiger compared with 4/10 (40%) farms for N. filicollis (p<0.05). In samples collected following treatment, a mean of 83 (min 46, max 100)% of Nematodirus spp. larvae recovered from the untreated groups were N. spathiger, compared with 94 (min 45, max 100)% in the ABZ treated groups (p=0.03). This change in percentage was not influenced by the overall efficacy of treatment based on the FECR test (p=0.324).

CONCLUSION: The results confirm the high level of resistance in N. spathiger in New Zealand and that benzimidazole resistance was more common in N. spathiger than N. filicollis. While resistance to benzimidazole anthelmintics has been reported previously in New Zealand, this is the first report of N. filicollis being resistant to benzimidazole anthelmintics.  相似文献   

Comparison of three methods of tonometry in horses presented for ophthalmic disease     

Emily Latham  Nicole M. Scherrer  Darko Stefanovski 《Veterinary ophthalmology》2023,26(5):422-427

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Continuing professional development     

WE CHAMBERLIN 《Australian veterinary journal》1993,70(3):120-120

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Assessment of the potential toxicity of a poison for rabbits, pindone (2-pivalyl 1, 3 indandione), to domestic animals     

GR MARTIN  RJ SUTHERLAND†  ID ROBERTSON†  WE KIRKPATRICK  DR KING  PJ HOOD† 《Australian veterinary journal》1991,68(7):241-243

The toxicity of pindone, a rabbit poison, to horses, cattle, goats, chickens, dogs and cats was investigated, using extension of prothrombin time (PT) as an index of poisoning. The daily dose of pindone, administered for 5 days, ranged from 0.3 mg/kg for dogs to 2.5 mg/kg for chickens. This range of dose rates was considered to be indicative of the worst possible case that could arise following a campaign of baiting for rabbits. Although significant elevations in PT (more than double baseline values) were noted in all species other than horses, clinical signs of anticoagulant poisoning were not observed in any of the species tested. From the observed PT, cattle and cats appeared to be the most susceptible, and horses the least susceptible, to pindone toxicity. The half-lives of the elevated PT were calculated as 3.1 days for cattle, 2.8 days for goats and chickens, 1.9 days for horses and dogs and less than one day for cats. It is proposed that these half-lives can be used as a guide for determining the duration of treatment of pindone-affected animals.  相似文献   

Origin of the warped heliospheric current sheet     

Wilcox JM  Hoeksema JT  Scherrer PH 《Science (New York, N.Y.)》1980,209(4456):603-605

The warped heliospheric current sheet for early 1976 is calculated from the observed photospheric magnetic field by a potential field method. Comparisons with measurements of the interplanetary magnetic field polarity for early 1976 obtained at several locations in the heliosphere by Helios 1, Helios 2, Pioneer 11, and at the earth show a rather detailed agreement between the computed current sheet and the observations. It appears that the large-scale structure of the warped heliospheric current sheet is determined by the structure of the photospheric magnetic field and that "ballerina skirt" effects may add small-scale ripples.  相似文献   

Extrapolating species abundance across spatial scales   总被引：3，自引：0，他引：3  

WE Kunin 《Science (New York, N.Y.)》1998,281(5382):1513-1515

The analysis, measurement, and management of species abundance is central to ecology and conservation biology, but it has proved difficult to find a single index that adequately reflects the commonness or rarity of species across a range of spatial scales. Here, a scale-independent measure of species abundance is developed, using presence-absence maps at varying spatial resolutions. By extrapolating such "scale-area" curves, species abundance can be estimated accurately even at scales finer than those used to parameterize the model, a task that had previously been deemed impossible in principle.  相似文献