Prevalence of Bovine Dermatophilosis in a Tropical Highland Region of Ethiopia

A study was made of bovine dermatophilosis on 540 animals at a high altitude (2400–2500 m above sea level) in Ethiopia. Eighty-two (15.4%) of the animals were affected by the disease which was more prevalent in local animals than was previously assumed. There was a significant (p<0.05) difference in the prevalence among different age groups. However, the difference in the prevalence of the disease between males and females was not significant (p>0.05). Associated risk factors included the relatively high average annual rainfall and humidity, tick infestation (76%) and management, related to the mixed crop-livestock production system. The possible impact of the disease on Ethiopian agriculture is indicated.     

Hydatidosis of sheep and goats slaughtered at Addis Ababa Abattoir: prevalence and risk factors

Abattoir survey was conducted on 1,053 sheep and 639 goats slaughtered at Addis Ababa Abattoir, Ethiopia, between October 2007 and May 2008, with the objective to determine the prevalence of hydatidosis and assess the associated risk factors. Routine meat inspection procedure was employed to detect the presence of the cyst in visceral organs (lung, liver, and omentum). Hydatid cysts were found in 206 (19.94%) and 102 (16%) of the sheep and goats inspected, respectively. Statistically significant difference in infection rates was noted between the two species. Likewise, there was significant difference in infection rates between the two sexes and different age groups in both sheep and goats (P < 0.5). The study showed that hydatidosis is prevalent in Ethiopia. Thus, there is a need to introduce appropriate control measures to minimize the rate of infection and reduce the ensuing economic losses.     

A cross-sectional study of epizootic lymphangitis in cart-mules in western Ethiopia

A cross-sectional study was conducted to determine the prevalence of epizootic lymphangitis (EL) in 309 cart-mules (cart-pulling mules) in Bako and Ejaji towns, Western Ethiopia using clinical and microbiological examinations, between November 2002 and April 2003. The overall prevalence was 21% (CI = 16.6–26%). The clinical, histological and mycological characteristics of EL in a cart-mule were similar with those in a horse. There was significant (χ² = 133.5, P = 0.001) association between tick infestation and EL lesions in study cart-mules. Amblyoma coherence and Boophilus genera were the ticks collected from lesions of cases of EL, and thus played a predisposing role. In conclusion, our results showed that EL has high prevalence in cart-mules in the two towns.     

Equine histoplasmosis: Treatment trial in cart horses in Central Ethiopia

Therapeutic effects of Sodium Iodide (NaI), Potassium Iodide (KI), ground berries of "Endod" (Phytolacca dodecandra) and Penstrip were evaluated on 70 cases of equine hitoplasmosis (EH). Response to each treatment was assessed using clinical examination of the lesions. Statistically significant difference (P = 0.0036) in therapeutic effect was observed among the different remedies. Cases treated either with a combination of NaI and Penstrip (F = 6.34, P = 0.004) or "Endod" and Penstrip (F = 3.64, P = 0.031) demonstrated significant response. The difference in response to treatment between early and advanced cases of EH was statistically significant (t = 2.22, P = 0.0148).     

Nematode infection in fish from Cartagena Bay, North of Colombia

Parasitic nematode infection indices were recorded in different fish species collected at Cartagena Bay, North of Colombia. Among 19 studied species, the Mugil genus presented the highest prevalence (83.9-100%), although Sciades herzbergii, Caranx hippos and Centropomus undecimalis were also found infected with nematodes. Parasites were found in the liver, intestinal mesenteries and encysted near the intervertebral joints, with an average parasite abundance of 4.0 ± 0.3 nematodes per fish. Morphological analysis allowed the identification of these nematodes as Contracaecum sp. A small, but positive correlation was found between parasite abundance and length (R=0.294, P<0.001) and weight (R=0.244, P<0.001). In contrast, the correlation between parasite abundance and condition factor was negative (R=-0.191, P<0.001). These results are the first describing the presence of nematodes in several fish species of this ecosystem, and it highlights the need for monitoring parasitism in Mugil species in order to avoid parasite ingestion during fish consumption.     

Comparative diagnosis of parasitological,serological, and molecular tests in dourine-suspected horses

Study on comparative sensitivity of parasitological, serological, and molecular tests on 237 horses originating from two dourine-suspected districts of Arsi-Bale highlands of Ethiopia was conducted to determine the prevalence of the disease and degree of agreement of the diagnostic tests. Accordingly, the prevalence of the disease was found to be 4.6%, 36.7%, and 47.6% by parasitological Woo test, RoTat 1.2 and 18S PCR tests, respectively. The seroprevalence of the disease was 27.6% in CATT/Trypanosoma evansi test. In Ethiopia, it was for the first time that trypanosomes from dourine suspected horses were demonstrated in 4.6% of the animals using Woo test. The findings of the present study disclosed that dourine is highly prevalent and one of the major diseases of horses in the area. There was no statistically significant difference (P > 0.05) in prevalence of the disease between districts, sexes, and age groups of the animals. However, there was a statistically significant difference (P < 0.05) in the prevalence of the disease between emaciated and animals with good body condition. Assessment of the degree of agreement of the diagnostic tests employed revealed low to fair ( k = 0.1 - 0.4 ) \left( {k = 0.{1} - 0.{4}} \right) with significantly higher sensitivity by PCR than other tests.     

Epidemiology and seasonal dynamics of gastrointestinal nematode infections of sheep in a semi-arid region of eastern Ethiopia

A study on the epidemiology and seasonal dynamics of gastrointestinal nematode infections of sheep was carried out in a semi-arid region of eastern Ethiopia for 2.5 years (May 2003 to September 2005). The experimental flock comprised a total of 60 Black Head Ogaden sheep, consisting of four equal groups of young male and female and old male and female sheep. These grazed on communal pastures together with a larger university flock, as well as with animals owned by neighbouring small-holder farmers. A new experimental flock was established each year of the study. Parasitological data (EPG, faecal culture L3, PCV and FAMACHA estimates) and animal performance (weight change) were recorded each month on all experimental animals. In addition, four tracer lambs were assigned each month to the flock to determine the seasonal patterns of infective larvae acquired from pasture. Results showed distinct seasonal patterns associated with the bi-modal annual rainfall. High levels of infection occurred during the short and long rain seasons with peaks occurring in May and September of each year. Haemonchus contortus was the most prevalent parasite, followed by Trichostrongylus spp., with a number of other nematode species being occasionally recorded. H. contortus showed and increased propensity to undergo arrested development during the dry seasons. Correlations between EPG and PCV, EPG and FAMACHA eye scores, and PCV and FAMACHA eye scores were all highly significant (P<0.001). However, there was no significant association between the EPG and LW of the study animals during each study year. This information will provide a basis for developing epidemiologically based control strategies for gastrointestinal nematode parasites that are appropriate for flocks owned by small-holder farmers of semi-arid areas of eastern Ethiopia.     

Prevalence and seasonal incidence of nematode parasites and fluke infections of sheep and goats in eastern Ethiopia

Sissay, M.M., Uggla, A. and Waller, P.J., XXXX. Prevalence and seasonal incidence of nematode parasites and fluke infections of sheep and goats in eastern Ethiopia. Tropical Animal Health and Production, XXXX. A 2-year abattoir survey was carried out to determine the prevalence, abundance and seasonal incidence of gastro-intestinal (GI) nematodes and trematodes (flukes) of sheep and goats in the semi-arid zone of eastern Ethiopia. During May 2003 to April 2005, viscera including liver, lungs and GI tracts were collected from 655 sheep and 632 goats slaughtered at 4 abattoirs located in the towns of Haramaya, Harar, Dire Dawa and Jijiga in eastern Ethiopia. All animals were raised in the farming areas located within the community boundaries for each town. Collected materials were transported within 24 h to the parasitology laboratory of Haramaya University for immediate processing. Thirteen species belonging to 9 genera of GI nematodes (Haemonchus contortus, Trichostrongylus axei, T. colubriformis, T. vitrinus, Nematodirus filicollis, N. spathiger, Oesophagostomum columbianum, O. venulosum, Strongyloides papillosus, Bunostomum trigonocephalum, Trichuris ovis, Cooperia curticei and Chabertia ovina), and 4 species belonging to 3 genera of trematodes (Fasciola hepatica, F. gigantica, Paramphistomum {Calicohoron} microbothrium and Dicrocoelium dendriticum) were recorded in both sheep and goats. All animals in this investigation were infected with multiple species to varying degrees. The mean burdens of adult nematodes were generally moderate in both sheep and goats and showed patterns of seasonal abundance that corresponded with the bi-modal annual rainfall pattern, with highest burdens around the middle of the rainy season. In both sheep and goats there were significant differences in the mean worm burdens and abundance of the different nematode species between the four geographic locations, with worm burdens in the Haramaya and Harar areas greater than those observed in the Dire Dawa and Jijiga locations. Similar seasonal variations were also observed in the prevalence of flukes. But there were no significant differences in the prevalence of each fluke species between the four locations. Overall, the results showed that Haemonchus, Trichostrongylus, Nematodirus, Oesophagostomum, Fasciola and Paramphistomum species were the most abundant helminth parasites of sheep and goats in eastern Ethiopia.     

Study on Coccidiosis of Scavenging Indigenous Chickens in Central Ethiopia

An investigation was made into coccidiosis of 190 scavenging indigenous chickens between September 2000 and April 2001 in three selected agroclimatic zones, in central Ethiopia. This was done through clinical, postmortem and microscopic examinations. Data were processed by chi-square and Mantel-Haenzel test. The study indicated that 25.8% (49/190) of the chickens were infected with coccidiosis and found to harbour one to four different species of Eimeria. Of these infected chickens, 30 (15.8%) and 19 (10.0%) were positive for clinical and sub-clinical coccidiosis, respectively. There was a significant altitude difference (chi2 = 14.7, p <0.001) in coccidiosis prevalence: 42.2% in chickens from highland region followed by 21.5% in mid-altitude and 13.1% in low-altitude areas. When quantified, the prevalence of coccidiosis was 2.66 and 4.83 times higher in the high-altitude than in mid-altitude (odds ratio, OR = 2.66, p<0.05) and low-altitude (OR = 4.83, p<0.001) chickens. The pathogenic Eimeria species responsible for clinical coccidiosis were E. necatrix, E. acervulina, E. maxima and E. tenella. With increasing demand for poultry products in developing countries, knowledge of production constraints in traditional management practices could help devise control strategies for constraints on backyard poultry production systems.     

青藏高原东缘海拔对植物种子大小的影响

以青藏高原东缘600种植物种子为对象,就海拔对种子大小的影响展开系统性地研究。结果表明,1)整个区系内,植物种子大小与海拔呈极显著的负相关关系(n=600, R²=0.029, P<0.001),并且在2 000～3 000 m海拔梯度中,种子大小有先增大后减小的趋势; 2)草本植物种子大小与海拔呈极显著的负相关关系(n=512,R²=0.026,P<0.001),但是灌木(n=72, R²=0.004, P=0.616)和乔木种子大小(n=16, R²=0.005, P=0.795)随海拔虽有减小的趋势但无显著相关性;3)海拔较高地区的草本植物种子大小比同属的海拔较低的植物种子大11.5％(df=131, t=2.724, P=0.007),小于阈值±30%,草本植物属内种子大小与海拔无关。在132个草本植物种对中,与同属的低海拔物种相比,40.9％(54种)高海拔物种种子大,另外19.7%(26种)小,39.4％(52种)没有变化,由此,认为在青藏高原东缘强烈的选择压力下,海拔和系统发育综合因子对植物种子大小的影响由具体的某个属本身的特性所决定,不存在单一的海拔与属的种子大小变异模式。     

PREVALENCE,ASSOCIATION WITH STIFLE CONDITIONS,AND HISTOPATHOLOGIC CHARACTERISTICS OF TIBIAL TUBEROSITY RADIOLUCENCIES IN DOGS

A tibial tuberosity radiolucency is sometimes identified on lateral radiographs of canine stifle joints, however little is known about the cause or significance. The purpose of this study was to describe the prevalence, association with other stifle conditions, and histopathologic characteristics of tibial tuberosity radiolucencies in a group of dogs. Radiographs of all canine stifle joints over 5 years were evaluated. Presence or absence of a tibial tuberosity radiolucency was recorded by an observer who was unaware of clinical status. Patient signalment and presence of other stifle joint conditions were recorded from medical records. A tibial tuberosity radiolucency was found in 145/675 dogs (prevalence = 21.5%). Statistically significant associations were identified between tibial tuberosity radiolucency and stifle condition (P < 0.0001), breed size (P = 0.011), and younger age of presentation (P = 0.001), but not with gender (P = 0.513). Dogs with a tibial tuberosity radiolucency had higher odds of having a medial patellar luxation than dogs without (OR = 9.854, P < 0.0001, 95% CI 6.422–15.120). Dogs with a tibial tuberosity radiolucency had lower odds of having a cranial cruciate ligament rupture than dogs without (OR = 0.418, P < 0.0001, 95% CI 0.287–0.609). Four canine cadavers, two with normal stifles and two with tibial tuberosity radiolucencies, underwent radiographic, computed tomographic, and histologic examination of the stifles. Computed tomography revealed a hypoattenuating cortical defect in the lateral aspect of the proximal tibial tuberosity that corresponded histopathologically to a hyaline cartilage core. Findings indicated that the tibial tuberosity radiolucency may be due to a retained cartilage core and associated with medial patellar luxation in dogs.     

Meta-analysis of the prevalence of mastitis and associated risk factors in dairy cattle in Ethiopia

Mastitis is among the most prevalent disease that contributes for the reduction of milk production in dairy herds. Although several published studies have estimated the prevalence of mastitis, variation among studies is great. The objective of the present meta-analysis was to provide a pooled estimate of the prevalence of overall, clinical, and subclinical mastitis in dairy cattle in Ethiopia. A pooled estimate was also conducted by potential risk factors. The literature search was restricted to studies published in English language from January 2002 to June 2016. Meta-analysis of 39 studies was done under random effects model using metafor package in R software. The pooled estimate of the overall prevalence of mastitis on cow-basis was found to be 47.0% (95% confidence interval [CI]?=?42.0, 52.0). The pooled prevalence with the 95% CI for clinical and subclinical mastitis was 8.3% (95% CI?=?6.5, 10.3) and 37% (95% CI?=?32.9, 40.7) respectively. There is a statistically significant and high heterogeneity of the prevalence estimates between published studies. The odds of occurrence of mastitis were higher in cows at early (odds ratio [OR]?=?1.6; 95% CI?=?1.4, 1.8) and late lactation (OR?=?1.3; 95% CI?=?1.2, 1.5) than mid lactation, in cows with 3–4 (OR?=?1.5; 95% CI?=?1.4, 1.7) and >4 parity number (OR?=?2.9; 95% CI?=?2.6, 3.4) than those with 1–2 parity number. Previous history of mastitis, floor type, milking hygiene, and udder injury had also statistically significant effect on pooled prevalence of mastitis (P?<?0.05). The present study reported that there is high prevalence of mastitis in dairy cows in Ethiopia, which could contribute to the low productivity in lactating cows. The statistically significant association of risk factors such as floor type, milking hygiene, and presence of udder injury with mastitis may suggest that dairy farmers can reduce the occurrence of the disease by improving their management practices.     

Comparison of the prevalence of enteric viruses in healthy dogs and those with acute haemorrhagic diarrhoea by electron microscopy

Objectives: To evaluate prevalence of enteric viruses in healthy dogs and to compare it with prevalences in dogs with acute haemorrhagic diarrhoea. Methods: Faecal samples were collected from 200 healthy dogs and examined by electron microscopy for presence of viral particles. Data were compared with viral prevalences that had been determined retrospectively by electron microscopy for 936 dogs with acute haemorrhagic diarrhoea. Results: There were significantly more negative faecal samples among the healthy dogs (82.0 per cent) compared with 55.8 per cent in dogs with acute haemorrhagic diarrhoea (P<0.001). With a prevalence of 17.5 per cent, significantly more healthy dogs were shedding coronavirus compared with 11.6 per cent in dogs with acute haemorrhagic diarrhoea (P=0.034). Parvovirus was only detected in one healthy dog (0.5 per cent), thus with a prevalence that was significantly lower than 16.0 per cent detected in the dogs with acute haemorrhagic diarrhoea (P<0.001). Paramyxovirus was not found in any of the healthy dogs but was found in 9.3 per cent of dogs with acute haemorrhagic diarrhoea (P<0.001). Clinical Significance: Results suggest that shedding of parvovirus and paramyxovirus is strongly associated with acute haemorrhagic diarrhoea. However, coronavirus seems to be even more prevalent among healthy dogs, raising the need for further studies to investigate the strain-associated pathogenicity of this virus.     

Prevalence and species composition of ixodid ticks infesting horses in three agroecologies in central Oromia, Ethiopia

A cross-sectional study was conducted to determine the species composition and prevalence of ixodid ticks infesting horses in three agroecological zones in central Ethiopia. For this purpose, a total of 1,168 horses were examined for tick infestation. An overall prevalence of 39.04% of tick infestation on horses was recorded. A total of 917 adult ticks were collected from infested horses. Amblyomma, Boophilus, Rhipicephalus, and Hyalomma genera with the respective prevalence of 3.2%, 1.8%, 29.2%, and 4.7% were identified. In the study, Rhipicephalus evertsi evertsi was encountered with the highest prevalence (15.8%) whereas Amblyomma gemma was with lowest prevalence (1.5%). From the highland, Hyalomma marginatum rufipes (3.1%), Hyalomma truncatum (1.0%), and Boophilus decoloratus (0.3%) were identified. From the midland, R. evertsi evertsi (27.5%), Rhipicephalus pulchellus (18%), Amblyomma variegatum (3.6%), B. decoloratus (2.8%), H. marginatum rufipes (2.6%), H. truncatum (1.8%), and A. gemma (1.5%) were identified. R. evertsi evertsi, 107 (27.5%), was with the highest prevalence in the midland. From the lowland, R. pulchellus (22.3%), R. evertsi evertsi (20%), H. truncatum (3.6%), A. gemma (3.1%), B. decoloratus (2.3%), H. marginatum rufipes (2.1%), and A. variegatum (1.5%) were identified. In the lowland, R. pulchellus, 87 (22.3%), was the most abundant tick species. The overall prevalence of tick infestation on horses was significantly (P < 0.05) higher both in the midland, 225 (57.8%), and the lowland, 214 (54.87%), than the highland, 17 (4.4%). This suggests that horses in midland and lowland are at higher risk of tick infestation than those horses in the highland. Further studies on the role of ticks in transmission of diseases to equines and the importance of horses as alternative hosts in different parts of Ethiopia are needed.     

Tail-biting in outdoor pig production

A study was performed in five identical outdoor production units in the same geographic area using growing-finishing pigs of similar genetic makeup, age, diet and feed management. The severity of tail-biting (TS) was scored 1-4. The average group prevalence of bitten tails at slaughter on different farms was between 14.1+/-2.1% and 20.1+/-3.0% (P<0.05). The odds of a barrow being bitten were 2.9 times higher than those for a gilt. The most frequently recorded score of bitten tails was TS3, indicating moderate wounds with low grade infection. The prevalence of bitten barrows was positively correlated with the percentage of gilts in a group (r = 0.54, P<0.001). Pigs with zero TS score had no significantly higher weights at slaughter compared to pigs with a score of TS1. As the TS increased from 1 to 4, weights decreased (TS 1 to TS 2 to 4, P<0.05). TS 3 and 4 were positively (P<0.001) associated with subsequent carcass condemnation. We concluded that outdoor rearing does not prevent tail-biting.     

Risk factors of infestation by Psoroptes spp. mites in buffalo (Bubalus bubalis) at smallholder farms in the Nile Delta region, Egypt

The aim of the present study was to explore the prevalence and potential risk factors associated with infestation by Psoroptes spp. mites in buffalo at smallholder farms in the Nile Delta region, Egypt. A total of 318 out of 1234 buffalo in 77 small scale herds were examined. The age of buffalo varied from three months to seven years. In all, 53 (16.66%) buffalo were recorded to be infested; 51 (16.35%) with Psoroptes spp. mites and two cases (0.31%) with Chorioptes spp. mites. Multivariate logistic regression was performed for significant risk factors at univariate analysis on both animal and herd level. The results of multivariate analysis showed that, on the animal level, the prevalence was affected by animal age (P?<?0.01; OR: 0.71; CI 95%: 0.441–1.11), season (P?<?0.01; OR: 1.20; CI 95%:0.541–1.15), indoor management (P?<?0.001; OR: 6.625; CI 95%:2.489 –17.631) and rearing with other animals (P?<?0.01; OR: 2.22; CI 95%:1.340 –7.132). However, on the herd level, the prevalence was affected by indoor rearing (P?<?0.05; OR: 22.4; CI 95%:2.75–16.431), mixed rearing with other animal species (P?<?0.05; OR: 4.5; CI 95%:1.66–7.941), and season (P?<?0.01; OR: 2.3; CI 95%:0.575–2.426). Clinically, mild skin lesions with mild pruritis were significantly prevalent in buffalo with the infestation by Psoroptes spp. mites (P?<?0.001), where 33/51 cases showed mild lesions. Also, psoroptic mites had significant association with inappitence (P?<?0.001). The result of the present study indicates that Psoroptes spp. mites are the most prevalent in buffalo in the Nile Delta Region, Egypt. Moreover, recognition of risk factors associated with mange mites in buffalo may enable the practitioner to establish the most appropriate control measures.     

Risk factors for mortality associated with respiratory disease among Menz and Horro sheep in Ethiopia

A retrospective case-control study was conducted on 6718 sheep of two breeds (2772 Horro and 3946 Menz) on risk factors for mortality associated with respiratory disease (MARD) in Ethiopia, based on data collected between October 1993 and December 1997. Potential risk factors examined were breed, gender, age, month, and air temperatures.Fifty-four per cent of total deaths in the flock could be attributed to respiratory disease and the annual MARD rate ranged between 6.3 and 19.0%. There was significant breed (P<0.0001) and gender (P<0.0001) difference in MARD. The Horro breed had a higher (P<0.0001) annual MARD than the Menz breed (16.5+/-0.18 vs. 12.4+/-0.15%). A higher (P<0.0001) proportion of males suffered than females (15.1+/-0.23% vs. 13.8+/-0.13%). Age was also an important risk factor for MARD: there was a strong polynomial relationship (R(2)=0.91, P<0.0001) between MARD and age; the risk of being young if a sheep was a MARD case was high. MARD was high between October and March but relatively low between the months of April and September. There was a significant (P<0.05) negative cubic relationship (R(2)=0.49) between monthly MARD and monthly average minimum air temperatures. There was also a significant (P<0.01) positive exponential relationship (R(2)=0.61) between monthly MARD and average monthly daily deviation between maximum and minimum air temperatures.Timely health and management interventions focusing on these factors are necessary to alleviate losses from MARD. Understanding variations in MARD risk within a population can enhance early response to potential outbreaks, reducing losses.     

The prevalence of pyrethroid resistance phenotype and genotype in Rhipicephalus (Boophilus) microplus in Yucatan, Mexico

A field survey was conducted to evaluate susceptibility of Rhipicephalus (Boophilus) microplus to cypermethrin on 49 farms in three areas of Yucatan, Mexico. The modified larval packet test was used to evaluate larval mortality at different cypermethrin concentrations. Dose-mortality regressions, lethal concentrations (LC(50)-LC(99)), confidence intervals and slope were estimated by probit analysis. Phenotype was defined as susceptible, tolerant or resistant when the resistance factor (RF) derived from both LC(50) and LC(99) determinations were <3, 3-5 or >5, respectively. An allele specific PCR (AS-PCR) was used to determine the frequency of a sodium channel mutation (F1550I, Phe→Ile) associated with pyrethroid resistance. Overall, 26.5%, 40.8% and 32.6% of tick populations were susceptible, tolerant and resistant to cypermethrin, respectively. A substantial inter-population variation in the level of cypermethrin response was evident (resistance factors ranged from 0.3 to 2599 and from 0.7 to >5000 when were indicated by the LC(50) and LC(99), respectively). The F1550I mutation (R allele) in R. microplus was present in all studied areas. The increasing presence of the R allele correlated well with increased levels of response indicated by both the LC(50) (r(2)=0.659, p=0.001) and LC(99) (r(2)=0.688, p=0.001) to cypermethrin. These results indicated that the F1550I mutation is a major common mechanism responsible for pyrethroid resistance in field populations of R. microplus ticks in the Mexican tropics. Both bioassay and AS-PCR showed that the prevalence of cypermethrin-resistant/tolerant R. microplus is high in Yucatan, Mexico and the relationship between the RF and the frequency of the R allele supports the role of F1550I as one of the most important mechanisms conferring pyrethroid resistance in these R. microplus populations.     

Occurrence of multidrug resistant Salmonella in antimicrobial-free (ABF) swine production systems

This cross-sectional study was conducted to determine the prevalence and antimicrobial resistance of Salmonella species in swine reared in the intensive (indoor) and extensive (outdoor) ABF production systems at farm and slaughter in North Carolina, U.S.A. We sampled a total of 279 pigs at farm (extensive 107; intensive 172) and collected 274 carcass swabs (extensive 124; intensive 150) at slaughter. Salmonella species were tested for their susceptibility against 12 antimicrobial agents using the Kirby-Bauer disk diffusion method. Serogrouping was done using polyvalent and group specific antisera. A total of 400 salmonellae were isolated in this study with a significantly higher Salmonella prevalence from the intensive (30%) than the extensive farms (0.9%) (P<0.001). At slaughter, significantly higher Salmonella was isolated at the pre- and post-evisceration stages from extensively (29% pre-evisceration and 33.3% post-evisceration) than the intensively (2% pre-evisceration and 6% post-evisceration) reared swine (P<0.001). The isolates were clustered in six serogroups including B, C, E1, E4, G and R. Highest frequency of antimicrobial resistance was observed against tetracycline (78.5%) and streptomycin (31.5%). A total of 13 antimicrobial resistance patterns were observed including the pentaresistant strains with ampicillin, chloramphenicol, streptomycin, sulfamethoxazole, tetracycline resistance pattern observed only among isolates from the intensive farms (n=28) and all were serotype Salmonella typhimurium var. Copenhagen. In conclusion, this study shows that multidrug resistant Salmonella are prevalent in ABF production systems despite the absence of antimicrobial selection pressure. In addition, it also highlights the possible role played by slaughterhouse and other environmental factors in the contamination and dissemination of antimicrobial resistant Salmonella in ABF production systems.     

垂穗披碱草种质资源繁殖相关特性遗传多样性研究

对采自甘肃、青海以及四川等地的50个垂穗披碱草居群的穗长、穗宽、每穗小穗数、种长、芒长和千粒重等6个与其繁殖相关的性状进行了遗传多样性研究。Shannon-weaver指数分析显示,50个居群在形态性状上具有丰富的遗传多样性(H′=1.873)。遗传多样性主要集中在居群内部(63.8%),居群间存在一定的遗传变异(36.2%)。各性状间的遗传变异具有不均衡性,穗宽变异较大(CV=0.347 2),种长变异最小(CV=0.118 4)。聚类分析表明,50个居群可分为3组;相关分析结果表明,海拔、经度、纬度、年均温和年均降水量对垂穗披碱草的繁殖性状变异有不同程度的影响,其中海拔和年均温对穗长和每穗小穗数影响极显著(P<0.01)。此外,提出了垂穗披碱草的利用和保护建议。