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1.
A field study was conducted on a 2,300-sow piggery in southwestern New South Wales, Australia, over a 17-wk period (from weaning at 4 wk of age) to assess the suitability for lifetime traceability of weaners of 4 identification devices: 1) full duplex ear tag (FDX, Allflex), 2) half duplex ear tag designed for cattle (HDX, Leadertronic), 3) conventional ear tag (Leader), and 4) ear tattoo (Ketchum ear tattoo 101). Visual readability, retention rate, electronic failures, and adverse side effects were assessed at 8 wk after application at both sites and before slaughter at 14 or 17 wk after application at site A and site B, respectively. A total of 394 weaner pigs were randomly assigned after weaning to 6 treatment groups and reared either in small groups in intensive, indoor, concrete-based pens (n = 224; site A) or in a large group on deep litter (n = 170; site B). Visual readability was similar for all ear tag types before slaughter (P > 0.05); however, visual readability of the ear tattoo was lower (P < 0.05), with between 78.2 and 60.0% illegible due to ink fading. Few tags were lost in the 8-wk period after application; however, tag loss increased for each tag device after this period and varied with housing system. Conventional tag loss was greater among pigs housed at site A (29.0%) than in pigs housed at site B (4.9%) in the 6- to 9-wk period before slaughter. The overall readability of FDX and HDX tags did not differ (P > 0.05) between sites; however, overall readability of FDX tags at 98.4% was better (P < 0.05) than 71.8% for HDX tags. Tag costs ranged from $0.73 for the conventional ear tag to $2.42 for the HDX ear tag. The identification devices did not induce production-limiting adverse effects after they were applied. Under conditions of this study, FDX electronic ear tags were the most efficacious for lifetime identification of weaner pigs on-farm.  相似文献   

2.
A total of 351 Iberian pigs with equal numbers of both sexes from 2 commercial farms were used to study the ability of various identification devices to guarantee the traceability required for labeled meat products from Iberian pigs reared under extensive production conditions in Spain. The performance of tattoos, visual ear tags, electronic ear tags, and i.p.-injected transponders of half duplex and full duplex technologies were compared during a production cycle from nursery to slaughter at 15 mo of age (156 +/- 3 kg of BW). No major health reactions to any of the identification methods were detected. Results showed that tattooing was not an adequate identification procedure due to reading difficulties as a consequence of dark skin, soiled appearance, and figure deformation. Ear tag losses and failures were affected by fencing type and increased in one of the farms (20.4 and 15.7% for losses and failures, respectively; P < 0.05) as a consequence of using barbed-wire fences. Ear tag losses decreased when fences changed to stone blocks at 365 d of age. Visual and electronic ear tag losses during transport and slaughter were low (3.7% for visual and 3.1% for electronic tag). Results of injectable transponders during the growing-fattening period were variable and were more readable for the half duplex than for the full duplex i.p. transponders (92.0 vs. 68.7% +/- 1.5; P < 0.05). Handheld transceivers worked properly under extensive conditions, although the body size and skin characteristics of the Iberian breed might limit the performance of reading devices, and the use of transceivers with longer reading distances is recommended. The main problem observed with i.p. transponders was their low recovery rate at slaughter due to the lack of adherence of the transponders to the omentum.  相似文献   

3.
The damaging effects of ear tags used to identify sheep were studied by examining the ears of sheep after slaughter in three different abattoirs and the ears of sheep on a farm. In total, 1040 ears with tags were examined. There were six types of ear tag: metal 'Ketchum' style loop tags; two-piece rigid plastic tags; 'Allflex' style flexible plastic tags with a male and female part; golf tee-shaped plastic ear tags; one-piece rigid plastic loop tags; and one-piece flexible plastic tags with a flap. The metal loop tags and plastic loop tags caused the most lesions, and the majority of the severe lesions. Ear tags placed near to the tip of the ear appeared to cause more damage. Some of the Ketchum style metal tags and two-piece rigid plastic tags appeared to be relatively new, as if recently fitted. These tags were more often associated with ear lesions, particularly moderate or severe lesions. The Allflex style flexible plastic tags caused the fewest problems, and the golf tee-shaped plastic tags also caused significantly fewer problems than the other tags.  相似文献   

4.
Traceability during slaughter was studied in 1,581 pigs identified by different devices. Treatments were visual ear tags (n = 1,300), electronic ear tags of different technologies (half-duplex, n = 636; full-duplex, n = 632), and intraperitoneally injected transponders of different technologies (half-duplex 32 mm, n = 645; full-duplex 34 mm, n = 642). Piglets were individually identified at weaning and intensively fed until 100 kg of BW. Pigs were slaughtered in 2 commercial slaughterhouses (including scalding, flaming, and peeling) at different throughputs (450 and 550 pigs/h). Readability during slaughtering was checked visually and using standardized hand-held transceivers. No effect of slaughterhouse was detected (P > 0.05). Ear tag losses in the slaughtering line were similar for visual (3.7%) and half-duplex (3.5%) but were increased for full-duplex (11.5%; P < 0.05). Moreover, electronic failures during slaughtering did not differ (P > 0.05) between ear tags (half-duplex, 1.1%; full-duplex, 0.6%). Intraperitoneally injected transponders were not affected by slaughtering (retention 100%, no failures), and 89.0% of the transponders were manually recovered from the abdominal viscera in the offal trays. The remaining transponders (11.0%) were lost on the floor, but none were found in the carcasses. No differences (P > 0.05) in recovery were observed between intraperitoneal transponders. Considering on-farm and slaughterhouse data, total traceability from farm to carcass release was greater (P < 0.05) for intraperitoneally injected transponders (98.2%) than for ear tags. Between ear tags, the greatest traceability was obtained with visual tags (95.7%), which differed (P < 0.05) from electronic tags (half-duplex, 91.4%; full-duplex, 84.5%; P < 0.05). Intraperitoneally injected transponders were an efficient and reliable identification system for tracing pigs from farm to the end of the slaughter line, allowing the transfer of pig identification to the carcass. Adherence of intraperitoneally injected transponders to the viscera should be improved to reduce risks of loss in the meat chain. A dual system based on intraperitoneally injected transponders and plastic ear tags would allow a redundant and automatic reading system that is efficient and reliable for data management and traceability in the swine industry.  相似文献   

5.
A total of 557 newborn piglets were used to compare eight identification devices, including one plastic ear tag as a control (C, n = 348) and two types of electronic ear tags (E1, n = 106; and E2, n = 103), and five types of injectable transponders (n = 557): small 12-mm (D12, n = 116; and S12, n = 110), medium 23-mm (T23, n = 108), and large (32-mm, T32, n = 115; and 34-mm, S34, n = 108). Injections were made s.c. in the auricle base (n = 248) and intraperitoneally (n = 309) using a new technique. All piglets were identified with two devices, but using electronic ear tags in conjunction with injection in the auricle was avoided on the same pig. Readability of devices was checked during fattening (until 110 kg BW) and slaughtering. On-farm losses were lower for control than for electronic ear tags (C = 1.1%; E1 = 8.8%; and E2 = 44.9%; P < 0.01); the latter also suffered electronic failures (E1 = 5.5%; and E2 = 55.1%; P < 0.001). On-farm losses of transponders injected in the auricle base were greater in large (S34 = 72.5%; and T32 = 46.3%; P < 0.05) than in small transponders (S12 = 19.4%; and D12 = 17.1%), but T23 (29.8%) only differed from S34. Transponder size did not affect on-farm losses for intraperitoneal injections in which only one loss was recorded (0.4%). All ear tags had similar losses during transportation to the slaughterhouse (1.2%), but no losses were observed in injectables. Slaughtering losses did not differ between ear tags (C = 11.2%; and E1 = 6.4%), but apart from losses, 12.8% of E1 failed electronically. Injection site affected losses and breakages during slaughtering (auricle base = 6.4%; and intraperitoneal = 0%), but recovery time did not significantly differ (auricle base = 28.6 s; and intraperitoneal = 18.9 s). Transponders in the auricle base were recovered by sight (30.2%), palpation (27.4%), or by cutting (42.5%). Intraperitoneal transponders were mainly recovered loose in the abdominal cavity (81.4%), whereas 18.6% fell on the floor. As a result, traceability varied significantly (P < 0.05) between control (86.7%) and electronic ear tags (0 to 68.1%) and injectable transponders, with the auricle base (17.8 to 75.0%) having lower values than intraperitoneal (98 to 100%). Intraperitoneal injection was a very effective tool for piglet identification and traceability, ensuring the transfer of information from farm to slaughterhouse. To warrant the use of this technique in practice, transponder recovery requires further investigation.  相似文献   

6.
The current study was conducted to assess the feasibility of fenbendazole (FB) administration to steers in a free choice mineral supplement. Provision of free choice FB reduces the need for handling of animals as well as decreases the level of animal parasitism. Two separate trials were conducted using 400 +/- 19 kg Holstein steers (n=14 and 17) during the months of July and August. Each steer was tagged with a unique electronic identification (EID) ear tag and randomly allocated into one of two groups. The tags worked in conjunction with a mineral feeder equipped with a load cell by registering the steer's EID number every time the animal entered the electromagnetic field. Individual daily mineral intake and feeding times were determined over two 8-day periods of non-medicated mineral (no FB), separated by a 14-day period of medicated mineral (0.55% FB). Fecal samples were collected at the beginning and end of each trial period and were analyzed for gastrointestinal nematode eggs and Giardia cyst. There was a consistently high level of attendance for the entire experimental period, with the exception of the first six days of the adaptation period. There were three preferential times for visiting the mineral feeder, approximately 07:00, 12:00 and 18:00 h. Individual daily mineral and FB intake was 229 +/- 27.21 g/day and 2 +/- 0.14 mg/kg BW/day, respectively, for the 14-day drug delivery period. The levels of fecal nematode eggs and Giardia cysts decreased significantly (<0.01) between pre- and post-sampling, with reductions of 92% for nematode eggs and 85% for Giardia cysts. Free choice medication for the control of gastrointestinal parasites is potentially effective, provided that the appropriate drug concentration, adaptation period, intake level and duration of treatment is utilized.  相似文献   

7.
Twelve types of electronic identification ruminal boluses of different dimensions were used to obtain a model for predicting their retention in the forestomachs of sheep. Boluses (n = 1,662) were made of ceramic materials, and their dimensions varied in o.d. (9 to 21 mm), length (37 to 68 mm), volume (2.5 to 21.0 mL), and specific gravity (0.85 to 3.91). Each bolus contained a half-duplex, standardized, glass-encapsulated transponder (32 x 3.8 mm). Boluses were administered to sheep (n = 1,497) of different ages by using the appropriate balling guns, and their retention under semiintensive conditions was recorded for at least 2 yr. When a bolus was lost, the sheep was rebolused with a heavier bolus. All sheep wore 2 plastic ear tags: one for the official control of health programs and the other for farm use. To determine the anatomical limit for a bolus passing through the gastrointestinal tract, the size of the reticulo-omasal orifice was measured in 46 adult sheep (male, n = 14; female, n = 32) that died by causes not related to bolus administration during the experiment. No signs of disease or growth alteration were detected in the bolused sheep. Total ear tag losses during the experiment period were 7.5% on average. Bolus retention (5 to 100%) varied according to bolus features and age of the sheep, but it showed a plateau after 18 mo. Inadequately dimensioned boluses were regurgitated or passed through the gastrointestinal tract and were excreted with the feces. The diameter of the reticulo-omasal orifice in adult sheep differed between male and female (23.1 and 21.8 mm, respectively; P < 0.01) and was greater than the o.d. of the retained boluses. Retention rate was predicted from bolus weight and volume by a logistic regression (R2 = 0.997; P < 0.001). When retention data from the literature (59.0 to 100%) were included in the model, the adjustment was slightly lower (R2 = 0.967). As a result, the minimum bolus weight estimated to reach a 99.5% retention rate in sheep varied between 16 and 45 g when volume varied between 3 and 22 mL, for boluses with a specific gravity between 2.0 and 5.2. In conclusion, bolus retention rate in sheep varied dramatically according to their features. For safe and efficient retention of electronic identification boluses in sheep, boluses of small volume and diameter (e.g., < 15 mm) with specific gravity and weight greater than 3.0 and 20 g, respectively, are recommended.  相似文献   

8.
为满足动物个体查找和定位,发光电子耳标应运而生。针对发光电子耳标的检测方法尚未出现,为应对此类产品的迅速推广,有必要对发光电子耳标测试方法进行研究。本文基于RFID射频技术测试原理,搭建发光电子耳标测试平台,通过发送发光指令,采集发光信号,实现了电子耳标发光性能的测试。  相似文献   

9.
A total of 1,822 pigs from 2 farms (farm A, n = 1,032; farm B, n = 790) were used to evaluate pig traceability under on-farm conditions by using identification devices (n = 4,434) of different technologies. The devices were visual ear tags (n = 1,533; Model 1, n = 776; Model 2, n = 757), electronic ear tags (n = 1,446; half-duplex, n = 702; full-duplex, n = 744), and intraperitoneally injected transponders (n = 1,455; half-duplex, n = 732; full-duplex, n = 723). A group of 790 pigs wore 3 types of devices, and 1,032 wore 2 devices. Piglets were identified before (wk 1 to 3 of age; farm A) or after (wk 3 to 4 of age; farm B) weaning and intensively fattened until approximately 100 kg of BW. Readability of devices was checked at each farm operation by using standardized handheld transceivers. No negative effects of the identification devices on animal health (mortality rate, 8.4%) or performance were detected. On-farm losses averaged 1.6% for ear tags (visual, 0.8%; half-duplex, 1.9%; full-duplex, 2.7%; P > 0.05) and 1.8% for intraperitoneally injected transponders (half-duplex, 1.7%; full-duplex, 1.9%; P > 0.05). Moreover, 1.4% electronic failures occurred in the electronic ear tags (half-duplex, 2.2%; full-duplex, 0.6%; P < 0.05) but not in the intraperitoneally injected transponders. Final on-farm readability was greater (P < 0.05) for visual ear tags (99.2%) than for electronic ear tags (half-duplex, 95.9%; full-duplex, 96.7%; P > 0.05). Readability for intraperitoneally injected transponders was intermediate (half-duplex, 98.3%; full-duplex, 98.1%; P > 0.05). Electronic devices were in all cases easier and faster to read than the visual ear tags. Visual ear tags and intraperitoneally injected transponders were efficiently retained under conditions of commercial pig farms, which agrees with the minimum values recommended by the International Committee for Animal Recording (> 98%). When readability and reading ease were also included as decision criteria, injectable transponders were preferred.  相似文献   

10.
With the objective of verifying the presumed identity of sheep in a traceability study based on visual ear tags and electronic boluses, retinal image recognition was used as an auditing biomarker on 152 lambs of 2 dairy breeds (Manchega, n=82; Lacaune, n=70). Lambs were identified with temporary ear tags (birth to weaning), and with official ear tags and electronic mini-boluses (weaning to yearling). At 3 mo of age, 58 lambs were recruited for flock replacement, and the rest were transported to a slaughterhouse. Retinal images (RI) and capturing times (CT) were recorded from the left and right eyes of each lamb in duplicate and by the same operator using an OptiReader device (Optibrand, Fort Collins, CO) at 3, 6, and 12 mo of age in 152, 58, and 58 lambs, respectively. The 3-mo RI were used as reference images and to assess operator training and accuracy of the technique. Intra- and inter-age comparisons were made to obtain the matching score (MS; 0 to 100) of pairs of RI from the same eye, using Optibrand's software. Operator skill improved with training sessions, but MS reached a plateau after the sixth session (264 images; MS=93.2 ± 1.5). Values of CT also decreased in trained compared with untrained operators (63 ± 5 vs. 144 ± 15 s, respectively; P < 0.001). Training data were eliminated from further analysis. Matching exclusion criteria were estimated from trained operator images at random (804 images) using a nonparametric receiver operating characteristic curve analysis for MS=70. No breed, eye, or age effects were detected in the MS intra-age comparisons at 3-, 6-, and 12-mo periods, which averaged 96.3 ± 0.3. Capturing time was longer in Lacaune than in Manchega lambs (P < 0.01) and decreased by age (34 ± 4 and 21 ± 2 s, for 6- and 12-mo periods, respectively; P < 0.001). Regarding lamb traceability, 2.8% temporary ear tags were lost from birth to weaning (traceability, 97.2%), but no official ear tag or mini-bolus losses were reported from weaning to yearling (traceability, 100%). Inter-age MS comparison, used as the biomarker for traceability auditing, did not vary by age or breed, on average being 92.6 ± 0.5. Using the 3-mo RI as reference, all 6- and 12-mo RI showed MS >70, which supported 100% lamb traceability. In conclusion, retinal imaging was an accurate technique for auditing the identity of living lambs from weaning to yearling.  相似文献   

11.
When in 2006 infection with bluetongue for the first time occurred in Germany the registered and already against flies and tabanids in cattle proofed Flectron ear tags were used against the blood feeding vector midges (Culicoides) also. However, the efficacy against gnats was not yet proofed. The efficacy of 1 and 2 ear tags (1,067 g cypermethrin per ear tag) per animal was investigated in North Germany with 237 heifers and dairy cows. Midges were caught in suction light traps close to the cattle on pasture or became trapped by mouth operated aspirators directly at the skin of the animal bodies. Within 12,051 specimens of midges 12 species of Culicoides could be identified. On grasslands 3 species, C. obsoletus, C. pulicaris and C. dewulfi were found to be dominant. These 3 species are also known to be vectors of BTV. The toxic efficacy was found for 14 days with 1 ear tag and up to 21 days with 2 ear tags. This duration of efficacy was confirmed in the laboratory with hair clippings from the dorsal line and the ventral abdomen (bioassay). In accordance with workers in the U.S.A. it is concluded that insecticide-impregnated ear tags will reduce the number of biting midges, and by this way the risk of infection with BTV in herds of treated cattle will be reduced as well as in other cattle of a particular region. It is concluded that ear tags are of considerable value as part of an integrated control program for BT, e.g. vaccination.  相似文献   

12.
电子耳标一方面可满足农业部对个体动物的唯一标识和疫病追溯要求；另一方面可携带个体动物从出生到屠宰整个生命周期所有关键信息,满足农场信息化管理需求,实现精细化饲养的目的,对其进行空中接口参数测试可确保其与识读器正常通讯。通过实验室间比对,可对空中接口参数测试比对结果进行统计分析,发现实验室存在的问题,进一步提高检测水平。2021年,中国兽医药品监察所组织三家机构共同开展了电子耳标空中接口参数测试的实验室间比对工作,并依据Z比分数统计法对检测结果进行了分析,分析结果显示：59组数据为满意；1组数据为有问题；0组数据为不满意,总体上看测试结果一致性较好。  相似文献   

13.
From 1991 to 1997, the yearly alternated use of synergized pyrethroid (lambda-cyhalothrin + piperonyl butoxide) and organophosphate (pirimiphos-methyl) ear tags was evaluated for the control of two pyrethroid-resistant horn fly populations in Louisiana. At each site, weekly fly counts were used to assess product efficacy. Control achieved by synergized pyrethroid ear tag treatments was reduced from 7 to 2 weeks and from 4 to 0 weeks at St. Joseph and Winnsboro, respectively. Control by organophosphate ear tags decreased from 15 to 3 weeks and from 10 to 7 weeks at St. Joseph and Winnsboro, respectively. The rotation of synergized lambda-cyhalothrin and pirimiphos-methyl ear tags did not improve pyrethroid ear tag efficacy or prevent further development of resistance to the pyrethroid or OP compound.  相似文献   

14.
Small ruminants play an important role in the epidemiology and transmission of Foot-and-Mouth Disease (FMD). The main reasons therefore are: FMD is difficult to diagnose as infected sheep not always show typical clinical symptoms or as the cardinal signs mimicked other diseases. Sheep and goats may be carriers. Infected herds which practice transhumance or are nomadic can spread the infection to other herds long before diagnose of the disease is established. Shipping and trade with live sheep and goats is much more common world wide than in other FMD susceptible species. Lack of registration of all sheep and goat herds (especially of small hobby herds) and lack of individual identifications signs (ear tags) may result in incomplete control measurements under FMD conditions. Basing on published experiences with the actual FMD epidemic in the UK and basing on the own experiences with the restrictions to prevent from spreading of the FMD from the UK to Germany suggestions for future disease control are made.  相似文献   

15.
This study investigated the prophylactic action of the chemical combination zeta-cypermethrin and piperonyl butoxide, administered by means of slow-release insecticide-impregnated ear tags, against biting midges (Culicoides spp) attacking sheep and against midges, horn flies (Haematobia irritant), stable flies (Stomoxys calcitrans), and houseflies (Musca domestica) attacking cattle. Treated sheep and cattle were protected 100 percent against blood-feeding midges for two months and there was a clear reduction in the number of midges collected from treated animals. Three days after the ear tags were attached to cattle, the number of horn flies on the cattle was reduced to practically zero and remained at a low level until the end of the trial (day 85). There was also a strong reduction in the numbers of stable flies and houseflies counted.  相似文献   

16.
The efficacy of ear tags containing 30% chlorfenapyr (total tag weight=13g) to control natural Haematobia irritans (L.) infestations was evaluated for Holstein heifers in Rafaela, province of Santa Fe, Argentina. A group of heifers (TG) was treated with two ear tags (one tag per ear). A control group (ACG) was maintained in a paddock adjacent to the TG paddock and, a distant control group (DCG) was maintained 700m apart from the other groups. From day 4 to day 98 after treatment, H. irritans infestations of ACG were significantly higher (P<0.05, test of Kruskal-Wallis) than the corresponding infestation of TG, but significantly lower than infestation in DCG, probably due to the proximity of TG. The chlorfenapyr control period, with an efficacy higher than 90% to reduce horn fly populations, lasted for 9 weeks when TG infestation was compared to fly numbers in ACG, but increased to 12 weeks in comparison to DCG. The results of this study show that ear tags impregnated with chlorfenapyr are a useful alternative to pyrethroids and organo-phosphate compounds for horn fly control.  相似文献   

17.
射频识别技术在牲畜电子耳标检测上的运用   总被引：1，自引：0，他引：1  
简要概述了射频识别的原理,对比了超高频电子耳标引用的国际标准ISO/IEC18000-6C和国家标准GB/T29768,对其中频率范围、编码方式等8个技术指标进行说明,对检测中的频点选择、链接时间T1的计算和识读距离等项目进行解释,以期为超高频电子耳标检测提供参考。  相似文献   

18.
鸭源新城疫病毒的分离鉴定   总被引：1，自引：0，他引：1  
从病死肉鸭肝脏中分离到2株病毒(ZH1、ZH2),均能够凝集鸡、肉鸭、绵羊、山羊、猪、人、兔、牛等的红细胞,且这种血凝性可被NDV标准阳性血清所抑制.参照NDV毒力判定标准及其方法对分离毒株ZH1、ZH2进行了鸡胚最小致死量平均死亡时间(MDT)、鸡胚半数感染量(EID50)以及1日龄鸡脑内接种致病指数(ICPI)测定,结果ZH1、ZH2株的MDT为52 h和44 h,EID50为106.4/0.1mL和108.64/0.1mL,ICPI为1.93和1.975.表明这2株分离病毒均为NDV强毒株.  相似文献   

19.
罗远明 《猪业科学》2021,38(9):52-54
智慧养猪已成为生猪产业发展的新趋势,其核心主要聚焦于智能环控、智能饲喂和对猪群的视频监控等技术的应用。大数据采集是实现智能化的前提,因此,通过射频识别（RFID）技术建立猪只大数据是实现智慧养猪的基础。通过正确的猪只个体识别技术的选型,在不同生命周期给猪只选配合适的电子耳标,给猪只建立精准的身份证明。在不同阶段的数据采集场景中,通过识别电子耳标产生真实数据的关联,准确掌握每一头猪从出生到屠宰再到消费市场终端之间的信息,从而确保了动物健康养殖、疫病控制和食品安全,真正意义上实现智慧养猪。  相似文献   

20.
The application of polymer matrix ear tags impregnated with 8.5% w/w cypermethrin to 6 wethers following shearing reduced lice to non-detectable levels on 4 of them at 29 weeks after tagging. At the conclusion of the study at 45 weeks the mean count of lice on tagged wethers was 3 per sheep compared to 158 on untreated wethers. In a second experiment, 6 non-infected sheep were treated at shearing with cypermethrin tags, 6 with 25 g/l cypermethrin backline formulation, 6 with tags plus backline and 6 were left untreated. Each group was exposed to 6 sheep with moderate to heavy infestations of lice. Compared to controls, all treatments delayed infestation, but cypermethrin tags gave no longer protection than backline treatment. All sheep were infested by 17 weeks after commencement of the study. At 45 weeks mean counts of lice were 38, 27, 20 and 74 respectively for sheep treated with tags, backline formulation, backline plus tags and untreated. Possible reasons for the better effect observed from applying tags to infested sheep than to sheep which were not infected at application but which were subsequently exposed to infested sheep are discussed.  相似文献   

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