Dairy farmers' knowledge, awareness and practices regarding bovine lameness in Malaysian dairy farms.

Given the data paucity on dairy farmers' perspectives regarding bovine lameness and hoof diseases, particularly in South East Asian countries, this study was conducted to assess the knowledge, attitude and practices toward lameness and hoof health among dairy cattle farmers in Malaysia. An online-based and face-to-face survey was conducted among 114 dairy farmers from four states in Peninsular Malaysia. Data were analysed using descriptive statistics, principal component analysis and an independent sample t-test. Overall, farmers demonstrated satisfactory knowledge and attitude regarding lameness and its impact on dairy cattle welfare and production. Lameness was ranked the second most important health issue in dairy farms after mastitis. Notably, 90% reported the presence of at least one lame cow on their farms, and 55% stated lameness as the reason for culling their cows. While sole ulcer was the hoof lesion mostly identified by farmers, 75% of them underestimated lameness prevalence on their farms and rarely implemented management strategies such as preventive hoof trimming and footbath. Farmers' educational qualification influenced their understanding of the impact of lameness on dairy cattle production. Despite reflecting satisfactory knowledge and attitude towards lameness in dairy cows, farmers in this study need to improve their current management practices to address lameness problem in their herds. Educating farmers on the importance of early detection and prompt treatment, and preventive measures are crucial for lameness control and improving hoof health in these dairy farms.

Gastrointestinal Parasites in Asian and African Elephants: A Systematic Review.

Gastrointestinal parasites (GIPs) in elephants have been reported in several studies over the last decades. Nonetheless, comprehensive data on clinicopathology of elephant GIPs, parasite burden threshold value, and the effectiveness of conventional anthelmintic drugs are still lacking. Herein, we have systematically reviewed the available knowledge on elephant GIPs identified among different parts of the world based on their prevalence, epidemiology, pathology, diagnosis, treatment, and control. Two electronic databases were searched for publications that met the inclusion criteria. About19 English journal articles published between year of 2011- 2021 were included. The main GIPs reported in elephants were Cyathostomidae (at least 14 species), Ancylostomidae, Haemonchus contortus, Trichostrongylus colubriformis, Oesophagostomum columbianum, Oesophagostomum aceleatum, Ascarids, Trichurids, Strongyloides, Anophlocephalidae, flukes, and Coccidia across different parts of the world, including Malaysia, Indonesia, Thailand, Myanmar, Sri Lanka, India, Kenya, Nigeria, and South Africa. Most elephants show no clinical signs until the equilibrium between parasite and host is disturbed. The common diagnostic methods for GIPs are traditional direct smear, faecal floatation, sedimentation, and McMaster egg counting technique, all involving morphological identification. However, some articles described the use of molecular detection to characterise common GIPs of elephants. Although benzimidazoles and macrocyclic lactones group of anthelmintic are the most conventional GIPs treatment and control for captive and semi-captive elephants, there is limited data on the threshold value of faecal egg count as the baseline for treatment decision. Over the last decades, various studies regarding elephant GIPs have been conducted. However, more focused and systematic studies are required to enhance our knowledge in multiple aspects of elephant parasitology to find effective solutions and improve elephant health.

Gastrointestinal Parasites in Asian and African Elephants: A Systematic Review

@#Gastrointestinal parasites (GIPs) in elephants have been reported in several studies over the last decades. Nonetheless, comprehensive data on clinicopathology of elephant GIPs, parasite burden threshold value, and the effectiveness of conventional anthelmintic drugs are still lacking. Herein, we have systematically reviewed the available knowledge on elephant GIPs identified among different parts of the world based on their prevalence, epidemiology, pathology, diagnosis, treatment, and control. Two electronic databases were searched for publications that met the inclusion criteria. About19 English journal articles published between year of 2011- 2021 were included. The main GIPs reported in elephants were Cyathostomidae (at least 14 species), Ancylostomidae, Haemonchus contortus, Trichostrongylus colubriformis, Oesophagostomum columbianum, Oesophagostomum aceleatum, Ascarids, Trichurids, Strongyloides, Anophlocephalidae, flukes, and Coccidia across different parts of the world, including Malaysia, Indonesia, Thailand, Myanmar, Sri Lanka, India, Kenya, Nigeria, and South Africa. Most elephants show no clinical signs until the equilibrium between parasite and host is disturbed. The common diagnostic methods for GIPs are traditional direct smear, faecal floatation, sedimentation, and McMaster egg counting technique, all involving morphological identification. However, some articles described the use of molecular detection to characterise common GIPs of elephants. Although benzimidazoles and macrocyclic lactones group of anthelmintic are the most conventional GIPs treatment and control for captive and semi-captive elephants, there is limited data on the threshold value of faecal egg count as the baseline for treatment decision. Over the last decades, various studies regarding elephant GIPs have been conducted. However, more focused and systematic studies are required to enhance our knowledge in multiple aspects of elephant parasitology to find effective solutions and improve elephant health.

Gastrointestinal parasitic infections of buffaloes (Bubalus bubalis) in Sarawak Borneo: Prevalence, risk factors, and farming practices.

The objectives of this study were to investigate the prevalence and associated risk factors for gastrointestinal (GI) parasites in buffaloes from various areas of Sarawak, and to assess current management practices of GI parasites among farmers. Faecal samples were collected from 15 farms and 129 animals, as well as data on farm and animal-based characteristics. A total of 129 faecal samples were examined for GI parasites using a modified McMaster and sedimentation. Association between potential risk factors and the prevalence of GI parasites was investigated using Chi-square statistic. The prevalence of Paramphistomum sp., strongyles, and coccidia were 75.2% (95% CI±7.5), 52.7% (95% CI±8.6) and 48.1% (95% CI±8.6), respectively. Farms which had a grazing area less than 50 acres in size had significantly higher prevalence of strongyles (70.5%, χ2 = 8.34, P = 0.004) and paramphistomes (88.6%, χ2 = 6.46, P = 0.01) relative to farms with a larger grazing area (43.5% and 68.2%, respectively). Prevalence of strongyles was lower in farms that did not implement a cut- and-carry system (45.6%, χ2 = 4.17, P = 0.04) in comparison to those that did (64%). The prevalence of paramphistomes was higher on farms with more than 40 animals (80.6%, χ2 = 3.18, P = 0.05) relative to farms with fewer animals. The majority of farmers surveyed (67.9%) showed awareness of GI parasite infection and reported that they recognized the associated symptoms. Most farmers practised deworming, and ivermectin was the most commonly used anthelminthic (60.4%); only 1.9% of farmers used albendazole. Overall this study revealed a high prevalence of GI parasites in buffalo in Sarawak. Although farmers report they are aware of parasitic diseases, further education is still required. This could include how they can successfully implement on-farm changes to reduce the prevalence of GI parasites in their herds.

A modified functional hoof trimming technique reduces the risk of lameness and hoof lesion prevalence in housed dairy cattle.

The objective of this study was to compare the impact of the functional hoof trimming (HT) method to an adaptation that results in increased modelling of the weight bearing claw on time to lameness and lesion prevalence in housed dairy cows. A total of 418 non-lame cows at early and late lactation were enrolled in the study and randomly allocated into 3 groups: functional HT (TRIM1), adaptation method (TRIM2), and an untrimmed group (CON). Locomotion scores (LS; 5-point scale) and animal-based welfare measures were assessed monthly from enrolment until the following 270 days in milk. Cows were considered lame when 2 consecutive LS = 3, or any assessment with a score of 4 or 5. Kaplan-Meier analysis was used to evaluate the difference in time to lameness between the groups. Multivariable CC Cox regression models were fitted to assess associations between covariates and time to lameness event, while associated factors for lesion prevalence were estimated using logistic regression models. The incidence rate of lameness was 29.3 cases/100/month, with corresponding rates of 28.7, 15.8 and 42.8 cases/100/months, in TRIM1, TRIM2 and CON, respectively. Time to first lameness event was higher in TRIM2 (mean ± S.E; 8.26 ± 0.16, P = 0.03) than CON (7.32 ± 0.2) and tended to be higher than TRIM1 (7.83 ± 0.19; P = 0.07). The risk of new lameness event was higher in cows with low BCS (≤2.5) (Hazard ratio; HR = 1.5; 95 % CI 1.1-2.1), while trimming all feet was a protective factor (HR = 0.58; 95 % CI 0.38-0.90). The prevalence of hoof lesions in the study population was 36.3 %, with the highest prevalence in CON (45.6 %), followed by TRIM1 (34.6 %) and TRIM2 (28.1 %). Seventy-eight per cent of hoof lesions were non-infectious and the majority of cows with hoof lesion in TRIM1 (72.3 %), CON (74.6 %) and TRIM2 (55.6 %) were lame. The odds of having a non-infectious hoof lesion were higher in CON (OR = 2.1; 95 % CI 1.2-3.7) compared to TRIM2, and in cows with hock injury (OR = 3.1; 95 % 1.1-9.7) relative to healthy hock, and tended to be higher in cows with low BCS (P = 0.09) relative to those with moderate BCS. Our results suggest that the adaptation to the functional method reduced the risk of lameness during lactation, however, proper management of under-conditioned cows is equally important.

Gastrointestinal parasitic infections of buffaloes (Bubalus bubalis) in Sarawak Borneo: Prevalence, risk factors, and farming practices

@#The objectives of this study were to investigate the prevalence and associated risk factors for gastrointestinal (GI) parasites in buffaloes from various areas of Sarawak, and to assess current management practices of GI parasites among farmers. Faecal samples were collected from 15 farms and 129 animals, as well as data on farm and animal-based characteristics. A total of 129 faecal samples were examined for GI parasites using a modified McMaster and sedimentation. Association between potential risk factors and the prevalence of GI parasites was investigated using Chi-square statistic. The prevalence of Paramphistomum sp., strongyles, and coccidia were 75.2% (95% CI±7.5), 52.7% (95% CI±8.6) and 48.1% (95% CI±8.6), respectively. Farms which had a grazing area less than 50 acres in size had significantly higher prevalence of strongyles (70.5%, χ² = 8.34, P = 0.004) and paramphistomes (88.6%, χ² = 6.46, P = 0.01) relative to farms with a larger grazing area (43.5% and 68.2%, respectively). Prevalence of strongyles was lower in farms that did not implement a cut- and-carry system (45.6%, χ² = 4.17, P = 0.04) in comparison to those that did (64%). The prevalence of paramphistomes was higher on farms with more than 40 animals (80.6%, χ² = 3.18, P = 0.05) relative to farms with fewer animals. The majority of farmers surveyed (67.9%) showed awareness of GI parasite infection and reported that they recognized the associated symptoms. Most farmers practised deworming, and ivermectin was the most commonly used anthelminthic (60.4%); only 1.9% of farmers used albendazole. Overall this study revealed a high prevalence of GI parasites in buffalo in Sarawak. Although farmers report they are aware of parasitic diseases, further education is still required. This could include how they can successfully implement on-farm changes to reduce the prevalence of GI parasites in their herds.

Cow- and herd-level factors associated with lameness in dairy farms in Peninsular Malaysia.

Lameness is a major welfare issue in dairy cows. This study was aimed at investigating the cow- and herd -level factors associated with lameness in dairy farms from four states in Peninsular Malaysia. The study population was 1001 lactating cows from 28 dairy farms located in Selangor (n = 9), Perak (n = 8), Negeri Sembilan (n = 6) and Johor (n = 5). Lameness was assessed by locomotion scoring. Individual cow characteristics such as breeds, parity, body condition score (BCS), hock condition, leg hygiene, presence of claw lesion and claw overgrowth were recorded. Data on herd characteristics, management practices and housing design were collected by on-farm inspection and farmers' interview. Mixed-eff ;ects logistic regressions were used to model the data and to assess the factors associated with lameness. Cow-level lameness prevalence was 34.2 % (95 % CI 22.2-50.0 %), with all the farms having at least one case of lameness. Claw lesions were recorded in 470 cows (46.9 %; CI 33.3-63.3 %) of which 296 (62.9 %) of them were lame. Of these, 78.9 % of the lesions were present on the rear feet and 25.5% of the cows had more than one foot affected. The proportion of cows having non-infectious and infectious claw lesions were 81.9 % and 18.1 %, and the predominant claw lesions were sole ulcers (24.9 %), white line disease (19.6 %), sole haemorrhage (10.2%), swelling of coronet (9.6 %), toe ulcers (8.4 %), and digital dermatitis (5.6%). Cows at third or more parities had higher odds of lameness (OR = 2.2; 95 % CI 1.2-4.1) compared to primiparous cows. Low BCS (< 2.5) increased the odds of lameness (OR = 4.8; 95 % CI 2.9-7.9) relative to cows with moderate BCS, and cows with hair loss around the hock (OR = 1.4; 95 % CI 1.1-1.9) relative to those with normal hock condition. Greater odds of being lame was observed in cows having claw lesion (OR = 15.2; 95 % CI 10.4-19.2) and those with overgrown claw (OR = 3.3; 95 % CI 2.4-4.5). There was increased odds of lameness in farms with high stocking density (OR = 1.8; 95 % CI 1.1-3.1), concrete floored walkways (OR = 1.9; 95 % CI 1.0-3.6), dirty floors (OR = 2.3; 95 % CI 1.9-3.7), and practicing preventive claw trimming (OR = 2.3; 95 % CI 1.9-4.6). Based on the high lameness prevalence, these findings could assist dairy farmers to make informed decisions on areas to implement on-farm changes to reduce lameness in the studied herds.

Prevalence of Toxoplasma gondii in pet and stray cats in Klang Valley, Malaysia.

Toxoplasma gondii, a zoonotic protozoan that has a worldwide distribution, is known to infect many warm-blooded vertebrates. The feline species including domestic cats are the definitive hosts for Toxoplama gondii and shed the infective oocyst. There is lack of information on the prevalence of Toxoplasma gondii in cats in Malaysia. The objective of this study was to determine both the seroprevalence of T. gondii and the prevalence of T. gondii DNA in cats' feces in Klang Valley, Malaysia. 198 blood and 201 fecal samples were collected from pet and stray cats from the local council, Dewan Bandaraya Kuala Lumpur (DBKL) and University Veterinary Hospital, Universiti Putra Malaysia respectively. The overall seroprevalence of Toxoplasma gondii in cats in the Klang Valley was found to be 5.5%. There was a high prevalence (10.5%) of T. gondii DNA detected in the cat fecal samples in both pet and stray cats suggestive of T. gondii oocyst shedding. Stray cats showed a higher seroprevalence and molecular prevalence of T. gondii than the pet cats. However, comparative analysis using Chi-square test showed no significant difference between both groups (P>0.05). Higher prevalence (10.5%) of cats shedding T. gondii DNA as compared to the seroprevalence (5.5%) was found in the cat population in the Klang Valley. The high prevalence of cats shedding T. gondii DNA is alarming as this may directly reflect the number of oocysts excreted into the environment posing a significant public health hazard.

First molecular detection of Tritrichomonas foetus in domestic cats in Klang Valley, Malaysia.

Tritrichomonas foetus is known to cause chronic diarrhea in the feline species in many different regions of the world. However, there is a paucity of information on T. foetus among cats in Malaysia. This study was conducted to determine the prevalence of Tritrichomonas foetus in the pet and stray cat population in Klang Valley, Malaysia. A total of 201 pet and stray cats' fecal samples were collected in Klang Valley. 24 samples were cultured in the InPouch® TF Feline to observe for motile trophozoites. A nested PCR protocol was used to screen for T. foetus in the collected samples. The prevalence of T. foetus in the cat population in Klang Valley was 33%. There was no association between Tritrichomonas infection and age, sex, breed or management of the cats. However, statistical analysis revealed that stray cats were more likely to be infected with T. foetus compared to pet cats. This study confirmed for the first time the presence of T. foetus among the cat population in Klang Valley, Malaysia.

First molecular detection of Tritrichomonas foetus in domestic cats in Klang Valley, Malaysia

@#Tritrichomonas foetus is known to cause chronic diarrhea in the feline species in many different regions of the world. However, there is a paucity of information on T. foetus among cats in Malaysia. This study was conducted to determine the prevalence of Tritrichomonas foetus in the pet and stray cat population in Klang Valley, Malaysia. A total of 201 pet and stray cats’ fecal samples were collected in Klang Valley. 24 samples were cultured in the InPouch® TF Feline to observe for motile trophozoites. A nested PCR protocol was used to screen for T. foetus in the collected samples. The prevalence of T. foetus in the cat population in Klang Valley was 33%. There was no association between Tritrichomonas infection and age, sex, breed or management of the cats. However, statistical analysis revealed that stray cats were more likely to be infected with T. foetus compared to pet cats. This study confirmed for the first time the presence of T. foetus among the cat population in Klang Valley, Malaysia.

Prevalence of Toxoplasma gondii in pet and stray cats in Klang Valley, Malaysia

@#Toxoplasma gondii, a zoonotic protozoan that has a worldwide distribution, is known to infect many warm-blooded vertebrates. The feline species including domestic cats are the definitive hosts for Toxoplama gondii and shed the infective oocyst. There is lack of information on the prevalence of Toxoplasma gondii in cats in Malaysia. The objective of this study was to determine both the seroprevalence of T. gondii and the prevalence of T. gondii DNA in cats’ feces in Klang Valley, Malaysia. 198 blood and 201 fecal samples were collected from pet and stray cats from the local council, Dewan Bandaraya Kuala Lumpur (DBKL) and University Veterinary Hospital, Universiti Putra Malaysia respectively. The overall seroprevalence of Toxoplasma gondii in cats in the Klang Valley was found to be 5.5%. There was a high prevalence (10.5%) of T. gondii DNA detected in the cat fecal samples in both pet and stray cats suggestive of T. gondii oocyst shedding. Stray cats showed a higher seroprevalence and molecular prevalence of T. gondii than the pet cats. However, comparative analysis using Chi-square test showed no significant difference between both groups (P>0.05). Higher prevalence (10.5%) of cats shedding T. gondii DNA as compared to the seroprevalence (5.5%) was found in the cat population in the Klang Valley. The high prevalence of cats shedding T. gondii DNA is alarming as this may directly reflect the number of oocysts excreted into the environment posing a significant public health hazard.

Knowledge, attitude and perception regarding antimicrobial resistance and usage among ruminant farmers in Selangor, Malaysia.

The increasing public health problem of antimicrobial resistance (AMR) has been linked to the extensive antimicrobial use (AMU) in food animals. We conducted a survey among ruminant farmers in Selangor, Malaysia to assess their level of awareness on AMR, attitudes towards AMU, and determinants that influence their practices. The survey was developed in English and Malay, validated, and administered to ruminant farmers in Selangor. A total of 84 farmers (response rate of 55%) completed the structured questionnaire. They appeared to be little aware of AMR and the impact on animals and public health. Indications of inappropriate AMU include their misconception on conditions requiring antibiotic therapy and easy accessibility to antibiotics. More than 70% (60/84) of the respondents believed that all sick animals need to be given antimicrobials. Half of the farmers especially those involved in the production of small and large ruminants; namely mixed ruminant farmers (MRF) (63%, 31/49) indicated that antimicrobials do not have any side effects in animals. Sixty-four percent (54/84) of the farmers have stored antimicrobials in their farms of which the practice was more common (P = 0.02) among the MRF compared to the single ruminant farmers (SRF). Although most of the farmers felt good farm biosecurity will help reduce AMU, they were indifferent regarding using antimicrobials only when prescribed by a veterinarian and non-storage of antimicrobials for later uses. Farmers with larger herd size (>100 animals/herd) and few years of farming experience agreed more to the suggestions about their role and that of veterinarians respectively in reducing the drivers of AMR. These areas might need to be considered by advisors to inform ruminant farmers on AMR and to encourage them for prudent AMU in food-producing animals.

Prevalence of lameness, claw lesions, and associated risk factors in dairy farms in Selangor, Malaysia.

The objectives of this cross-sectional study were to estimate the prevalence of lameness, claw lesions, and associated risk factors in dairy farms in Selangor, Malaysia. The sample population was 251 lactating cows from 8 farms assessed for lameness and claw lesions by locomotion scoring and claw assessment respectively while specific animal-based measures were hypothesized as cow-level risk factors. The Wilcoxon rank test and logistic regression were applied to assess the prevalence of lameness, claw lesions, and association with potential risk factors, respectively. The prevalence of lameness was 19.1% ranging from 10.0 to 33.3% while 31.1% of cows had claw lesions and ranged from 16.3-40%. Claw lesions were recorded in 87.5% of the lame cows with highest being those affected with sole lesions (54.2%) and white line disease (61.2%). Overall, the occurrence of overgrown claws, sole lesions, white line disease, and digital dermatitis were 37, 18.2, 10.9, and 8.3%, respectively. More than one claw lesion per cow was present in 71.8% of the affected cows. Lameness was associated with early lactation (OR = 3.3; 95% CI 2-7), injured hocks (OR = 4.8; 95% CI 5-17), and dirty legs hygiene (OR = 2.6; 95% CI 1.3-6.2), whereas presence of claw lesions was associated with dirty legs hygiene (OR = 4.7; 95% CI 4-11) and overgrown claw (OR = 2.7; 95% CI 1.4-5.3). To reduce the prevalence of lameness, farmers need to improve the management of cows with overgrown claw, injured hocks, and cleanliness by establishing routine claw trimming and efficient stall design.

Study on the use of toltrazuril to eliminate Neospora caninum in congenitally infected lambs born from experimentally infected ewes.

To determine if toltrazuril was effective in eliminating Neospora caninum infection from congenitally infected lambs. Twenty-eight ewes were allocated to 3 groups where animals in Groups A and B were inoculated with 1 × 10(7)N. caninum tachyzoites on Day 120 of gestation and Group C was maintained as a negative control group. Lambs born from ewes in Group A were treated with toltrazuril (20mg/kg) on Days 0, 7, 14 and 21 after birth. Lambs in Groups B and C were untreated. All lambs in Groups A and B were seropositive at 12 weeks of age. At 12 weeks of age, no differences between lambs in Group A and Group B were observed in serological results (ELISA and western blot), presence of N. caninum-related brain histopathological lesions or the number of organisms detected by qPCR. Group C remained negative for serology, detection of N. caninum DNA as well as histopathology throughout the study. Results indicate that N. caninum congenitally-infected lambs had a continuing infection with N. caninum despite being treated with toltrazuril.

Vertical transmission in experimentally infected sheep despite previous inoculation with Neospora caninum NcNZ1 isolate.

Recent reports indicate N. caninum has a possible role in causing abortions in sheep in New Zealand. Knowledge about the mode of transmission of neosporosis in sheep in New Zealand is limited. This study aimed to determine the rate of vertical transmission that would occur in lambs born from experimentally inoculated ewes and to determine if previous inoculation would protect the lambs from N. caninum infection. A group of 50 ewes was divided into 2 groups with one group being inoculated with 5×10(6) N. caninum tachyzoites prior to pregnancy in Year 1. In Year 2, each of these groups was subdivided into 2 groups with one from each original group being inoculated with 1×10(7) N. caninum tachyzoites on Day 120 of gestation. Inoculation of N. caninum tachyzoites into ewes prior to mating resulted in no congenital transmission in lambs born in Year 1 but without further inoculation, 7 out of 11 lambs in Year 2 were positive for N. caninum infection. Ewes that were inoculated in both years resulted in all 12 lambs born in Year 2 being positive for N. caninum infection. This indicates that previous inoculation in Year 1 did not result in any vertical transmission in that year but did not provide any protection against vertical transmission in Year 2. These results suggest that vertical transmission occurs readily once the ewe is infected.

Adaptation of a commercial ELISA to determine the IgG avidity in sheep experimentally and naturally infected with Neospora caninum.

Recent reports indicate Neospora caninum has a possible role in causing abortions in sheep in New Zealand. Knowledge about the epidemiology of neosporosis in sheep is limited. This study aimed to adapt and validate a commercially available ELISA assay as an IgG avidity assay to discriminate between acute (primary and re-inoculated) and chronic N. caninum infections in sheep. In addition, it was used to compare the antibody avidity values between lambs from ewes inoculated with N. caninum either during the pregnancy or in the previous year. The avidity assay was undertaken by using 6M urea for the first wash after incubation with the primary antibody in the commercial ELISA (Chekit* Neospora antibody test kit, IDEXX Laboratories, Australia). Sequential serum samples were obtained from naïve ewes (n=16) experimentally inoculated with live N. caninum tachyzoites. All ewes were seropositive by two weeks post-inoculation and remained seropositive for 20 weeks post-inoculation. There was a linear relationship between time after inoculation and avidity values (p<0.05) over the first 24 weeks. In Week 4, all animals had avidity values <35% and by Week 8, 8/16 animals had avidity values of >35%. These results suggest that an avidity value of <35% indicates a recent primary infection while a value of >35% is indicative of a chronic infection. The assay was then validated using samples from other groups of experimentally inoculated sheep as well as samples from naturally infected ewes. When comparing sample to positive ratio (S/P) and avidity values from lambs born from recently inoculated ewes with those from ewes inoculated the previous year and re-inoculated in the current year, it was possible to differentiate the lambs at 2 weeks of age. Lambs from recently inoculated ewes had low S/P and avidity values at 2 weeks of age which increased by 12 weeks of age. In comparison, lambs from re-inoculated ewes had high S/P and avidity values at 2 weeks of age, due to maternal antibody influence but values were similar to those from lambs that were born from recently inoculated ewes at 12 weeks of age. Avidity values for four naturally infected ewes were all >60% indicating chronic infection. These results suggest that the assay is able to discriminate between recent and chronic infection in sheep as well as able to differentiate lambs with maternal immunity compared to their own de novo immunity. As such it can be utilized to understand the kinetics of N. caninum infection in sheep.

Detection of Neospora caninum DNA in semen of experimental infected rams with no evidence of horizontal transmission in ewes.

Recent reports from New Zealand indicate Neospora caninum has a possible role in causing abortions in sheep. Transmission of N. caninum via semen has been documented in cattle. This study aimed to investigate if horizontal transmission through semen was also possible in sheep. Initially, 6-month old crossbred ram lambs (n=32), seronegative to N. caninum, were divided into 4 equal groups. Group 1 remained uninoculated whilst the remainder were inoculated with N. caninum tachyzoites intravenously as follows: Group 2 - 50 tachyzoites; Group 3 - 10(3) tachyzoites; Group 4 - 10(7) tachyzoites. Semen samples were collected weekly for 8 weeks for the detection of N. caninum DNA and quantified using quantitative PCR (qPCR). Plasma collected 1 month post-inoculation was subjected to ELISA (IDEXX Chekit) and Western blot. At 2 weeks post-infection, three rams from Group 1 (uninoculated) and three rams from Group 4 (10(7)tachyzoites/ml) were mated with two groups of 16 ewes over two oestrus cycles. Ewe sera collected 1 and 2 months post-mating were tested for seroconversion by ELISA and Western blot. All experimentally infected rams seroconverted by 1 month with ELISA S/P% values ranging from 11% to 36.5% in Group 2, 12-39.5% in Group 3 and 40-81% in Group 4. However, none of the ewes mated with the experimentally infected rams seroconverted. For the Western blot, responses towards immunodominant antigens (IDAs) were observed in ram sera directed against proteins at 10, 17, 21, 25-29, 30, 31, 33 and 37 kDa. Rams in Group 2, 3 and 4 were noted to have at least 3 IDAs present. None of the ewes showed any of the 8 prominent IDAs except for the one at 21 kDa which was seen in 30 out of 32 ewes in both groups. N. caninum DNA was detected intermittently in the ram's semen up to 5 weeks post-inoculation with the concentrations ranging from that equivalent to 1-889 tachyzoites per ml of semen. Low concentrations of N. caninum DNA were also detected in the brain tissue of two rams (Groups 1 and 4). These results suggest that although N. caninum DNA can be found in the semen of experimentally infected rams, the transmission of N. caninum via natural mating is an unlikely event.

Dose-titration challenge of young pregnant sheep with Neospora caninum tachyzoites.

Pregnant ewe lambs (7-8 months old at breeding) were inoculated intravenously at 90 days after joining with the ram with 50, 5 x 10(3), 10(6), or 10(8)Neospora caninum tachyzoites and outcomes were compared to a control group. Seroconversion was measured by indirect fluorescent antibody test (IFAT) at fortnightly intervals and by enzyme-linked immunosorbent assay (ELISA) at 28 days post-challenge. Seroconversion (by IFAT) occurred in all animals except for 2 sheep in the lowest dose group, including the 9 sheep in the control group. IFAT antibody titres rose and fell rapidly, peaking at 1:800 and in 8 animals was negative within 7 days of abortion. ELISA results more closely reflected infection dose and outcome of pregnancy than IFAT serology did. All 10 ewes in each of the 2 highest dose groups aborted, 5 of 10 ewes in the mid-dose group aborted and no ewes in the lowest dose or control groups aborted. Histological lesions consistent with N. caninum infection were seen in the brains of all 25 aborted lambs, as well as in 2 live-born premature lambs from the group receiving 5 x 10(3) tachyzoites and 2 clinically normal lambs (one from the control group). Polymerase chain reaction (PCR) detected N. caninum DNA in a variety of tissues from lambs, aborted foetuses and dams including 3 of 9 ewe-lamb pairs from the control group. The results from this study showed a strong relationship between challenge dose of N. caninum tachyzoites, the sample to positive (S/P) percentage in an ELISA test 28 days after challenge and pregnancy outcome. IFAT results did not correlate well with the level of challenge or the outcome of pregnancy and their relevance in studies of this kind should be questioned.