Nutrient requirements and low-cost balanced diets, based on seasonally available local feedstuffs, for local pigs on smallholder farms in Western Kenya.

Growth performance of pigs on smallholder farms in the tropics is low. Lack of feedstuffs, seasonal feed shortages, and feeding nutritionally unbalanced diets contribute to slow growth. Low-cost balanced diets are needed to improve pig performance. In this study, we estimated the nutrient requirements of local pigs on smallholder farms in Kenya and developed balanced low-cost diets using seasonally available local feedstuffs. Diets were formulated to provide pigs with 80 % of the nutrient density in corn and soybean meal-based (reference) diets to minimize the cost per unit of energy and other nutrients. Estimated requirements for starting and growing pigs (8 to 35 kg body weight) were as follows: digestible energy (DE) 2960 kcal/kg of dry matter (DM), standardized ileal digestibility (SID) lysine 5.8 g/kg of DM, calcium 2.8 g/kg of DM, standardized total tract digestible (STTD) phosphorous 1.4 g/kg of DM, and crude protein 85 g/kg of DM. Nutrient requirements of local pigs on smallholder farms in Kenya were lower than those of exotic breed pigs raised in commercial settings. Seasonally available local feedstuffs were used to develop low-cost balanced diets. Twenty-two diets are presented based on season, cost, and feedstuff availability. This study has broad applicability as a case study of an approach that could be applied in other tropical regions in which smallholder pig keeping is practiced and where local feedstuffs for pigs are available seasonally.

Molecular epidemiology of Campylobacter jejuni human and chicken isolates from two health units.

A study was conducted over a 2-year period in the Perth District and Wellington-Dufferin-Guelph health units in Ontario, with an objective of using comparative genomic fingerprinting (CGF) with a 40-gene assay (CGF40) to investigate the association between human cases of campylobacteriosis and spatially and temporally related Campylobacter isolates from retail chicken. CGF results were available for isolates from 115 human cases and 718 retail chicken samples. These data were combined with CGF results from a large reference database of Campylobacter isolates. Isolates were categorized into types based on >90% CGF40 fingerprint similarity (CGF-90%). CGF-90% types were categorized as chicken associated (CA90) when the proportion of animal isolates in the given type that originated from chicken was at least 80% and was statistically significant. Risk factor data were collected from cases by questionnaire. Urban cases were significantly more likely than rural cases to be CA90 and there were significantly fewer CA90 cases in the second year of the study. Due to the population distribution in Canada and most industrialized countries, the majority of campylobacteriosis cases are urban dwellers. Therefore, the association between urban cases and chicken-associated types of Campylobacter emphasizes the importance of educational and food safety efforts to reduce the impact of Campylobacter from retail chicken on public health. Sources other than chicken may be more important for rural dwellers.

An investigation of ear necrosis in pigs.

Porcine ear necrosis was investigated in 23 conveniently chosen farms, consisting of 14 case farms and 9 control farms. Biopsies of lesions and oral swabs from pigs on 11 case farms were examined by histology and bacterial culture. All farms were visited for observations and a survey on management, housing, and the presence of other clinical signs or behavioral vices. Histological examination revealed that the lesions began on the surface and progressed to deeper layers, and that vascular damage did not appear to be the initiating cause. Spirochetes were only rarely observed in histological examination and were not cultured from biopsies and oral swabs. Staphylococcus aureus and Staphylococcus hyicus were cultured from 91% and 66% of samples, respectively. Ear biting and a humid environment were associated with ear necrosis. On some farms large numbers of pigs were affected and lesions were sometimes extensive. The condition appears to be an infectious disease beginning on the surface of the skin; contributing environmental and management factors are likely.

Enquête sur la nécrose des oreilles chez les porcs. La nécrose des oreilles porcines a fait l'objet d'une enquête dans un échantillonnage de convenance de 23 fermes, composé de 14 fermes de cas et de 9 fermes témoins. Les biopsies de lésions et des prélèvements oraux faits chez des porcs dans 11 fermes de cas ont été examinés par histologie et culture bactérienne. Toutes les fermes ont été visitées pour recueillir des observations et effectuer un examen de la gestion, du logement et de la présence d'autres signes cliniques ou vices de comportement. L'examen histologique a révélé que les lésions commençaient sur la surface et progressaient vers des couches plus profondes et que les dommages vasculaires ne semblaient pas être la cause initiale. Des spirochètes ont été rarement observés à l'examen histologique et n'ont pas été cultivés dans les biopsies et les prélèvements oraux. Staphylococcus aureus et Staphylococcus hyicus ont été cultivés dans 91 % et 66 % des échantillons, respectivement. Les morsures d'oreilles et un environnement humide étaient associés à la nécrose des oreilles. Dans certaines fermes, un grand nombre de porcs étaient affectés et les lésions étaient parfois importantes. L'affection semble être une maladie infectieuse qui commence à la surface de la peau; des facteurs contributifs liés à l'environnement et à la gestion sont probables.(Traduit par Isabelle Vallières).

Average daily gain of local pigs on rural and peri-urban smallholder farms in two districts of Western Kenya.

The objective of this study was to determine the average daily gain (ADG) of pigs on rural and peri-urban smallholder farms in two districts of Western Kenya, in order to establish a baseline to measure the impact of future management interventions. Average daily gain (kilograms per day) for 664 pigs weighed one, two or three times and the proportion of local and crossbreed pigs was determined. Assuming a uniform birth weight of 1 kg, ADG did not differ between pigs weighed once or twice. Overall, ADG was higher in peri-urban pigs (0.15 ± 0.058 kg/day) than rural pigs (0.11 ± 0.047 kg/day). Pigs at 1 to 2 months had a higher ADG than those at 3 months or 10 to 12 months and ADG was higher in crossbreed than local pigs. Over the two districts, the ADG was low (0.13 ± 0.002 kg/day). Most (87.2 %) pigs were of local breed. Low ADG may be due to malnourishment, high maintenance energy expenditure, high parasite prevalence, disease, and/or low genetic potential. This low ADG of pigs raised on smallholder farms in Western Kenya indicates a high potential for improvement. The growth rate of pigs in Western Kenya must be improved using locally available feedstuffs to make efficient use of resources, promote sustainable smallholder pig production, and improve the livelihood of smallholder farmers.

Antimicrobial resistance and antimicrobial use associated with laboratory-confirmed cases of Campylobacter infection in two health units in Ontario.

AIM: A population-based study was conducted over a two-year period in the Perth District (PD) and Wellington-Dufferin-Guelph (WDG) health units in Ontario to document antimicrobial resistance and antimicrobial use associated with clinical cases of laboratory-confirmed campylobacteriosis. METHODS: Etest (bioMérieux SA, France) was used to determine the minimum inhibitory concentration of amoxicillin/clavulanic acid, ampicillin, chloramphenicol, ciprofloxacin (CIP), clindamycin, erythromycin (ERY), gentamicin, nalidixic acid and tetracycline. Data regarding antimicrobial use were collected from 250 cases. RESULTS: Of the 250 cases, 165 (65.7%) reported staying home or being hospitalized due to campylobacteriosis. Fifty-four per cent of cases (135 of 249) reported taking antimicrobials to treat campylobacteriosis. In 115 cases (51.1%), fecal culture results were not used for treatment decisions because they were not available before the initiation of antimicrobial treatment and/or they were not available before the cessation of symptoms. Of the 250 cases, 124 (49.6%) had available Campylobacter isolates, of which 66 (53.2%) were resistant to at least one of the antimicrobials tested. No resistance to ampicillin, chloramphenicol or gentamicin was found in these isolates. Six isolates (4.8%) were resistant to CIP. Two isolates (1.6%) were resistant to ERY; however, no isolates were resistant to both CIP and ERY. CONCLUSION: Prudent use practices should be promoted among physicians to reduce the use of antimicrobials for the treatment of gastroenteritis in general and campylobacteriosis in particular, as well as to minimize the future development of resistance to these antimicrobials in Campylobacter species.

OBJECTIF: Les chercheurs ont mené une étude en population pendant une période de deux ans dans les unités sanitaires du district de Perth et de Wellington-Dufferin-Guelph en Ontario, afin d'étayer la résistance antimicrobienne et l'utilisation d'antimicrobiens associées à des cas cliniques de campylobactériose confirmés en laboratoire. MÉTHODOLOGIE: Les chercheurs ont utilisé l'Etest (bioMérieux SA, France) pour déterminer la concentration inhibitrice minimale d'amoxicilline-acide clavulanique, d'ampicilline, de chloramphénicol, de ciprofloxacine (CIP), de clindamycine, d'érythromycine (ERY), de gentamicine, d'acide nalidixique et de tétracycline. Ils ont colligé les données sur l'utilisation d'antimicrobiens auprès de 250 cas. RÉSULTATS: Sur les 250 cas, 165 (65,74 %) ont déclaré être restés à la maison ou avoir été hospitalisés en raison de leur campylobactériose. Cinquante-quatre pour cent des cas (135 sur 249) ont déclaré avoir pris des antimicrobiens pour traiter leur campylobactériose. Dans 115 cas (51,1 %), les résultats de la coproculture n'ont pas été utilisés pour prendre les décisions thérapeutiques parce qu'ils n'étaient pas disponibles avant l'amorce du traitement antimicrobien ou avant l'arrêt des symptômes. Sur les 250 cas, 124 (49,6 %) disposaient d'isolats du Campylobacter, dont 66 (53,2 %) étaient résistants à au moins un des antimicrobiens testés. Les chercheurs n'ont relevé aucun cas de résistance à l'ampicilline, au chloramphénicol ou à la gentamicine dans ces isolats. Six (4,8 %) étaient résistants à la CIP et deux (1,6 %), à l'ERY, mais aucun n'était résistant à la fois à la CIP et à l'ERY. CONCLUSION: Il faudrait promouvoir des pratiques d'utilisation prudentes chez les médecins pour réduire l'utilisation d'antimicrobiens dans le traitement de la gastroentérite en général et de la campylobactériose en particulier, ainsi que pour limiter le plus possible l'apparition future de résistance à ces antimicrobiens dans les espèces de Campylobacter.

Identifying an outbreak of a novel swine disease using test requests for porcine reproductive and respiratory syndrome as a syndromic surveillance tool.

BACKGROUND: Animal disease monitoring and surveillance are crucial for ensuring the health of animals, humans and the environment. Many studies have investigated the utility of monitoring syndromes associated with data from veterinary laboratory submissions, but no research has focused on how negative test results from a veterinary diagnostic laboratory data can be used to improve our knowledge of disease outbreaks. For example, if a diagnostic laboratory was seeing a disproportionate number of negative test results for a known disease could this information be an indication of a novel disease outbreak? The objective of this study was to determine the association between the porcine circovirus associated disease (PCVAD) outbreak in Ontario 2004-2006 and the results of porcine reproductive and respiratory syndrome virus (PPRSV) enzyme-linked immunosorbent assay (ELISA) and the results of PRRSV polymerase chain reaction (PCR) diagnostic tests requested by veterinarians. RESULTS: Retrospective data were collected from the Animal Health Laboratory (AHL) at the University of Guelph, Guelph, Ontario Canada and were comprised of weekly counts of PRRSV ELISA and PRRSV PCR diagnostic tests requested by swine practitioners from 2000-2007. The results of the PRRSV ELISA and PRRSV PCRs were analysed separately in two models using logistic regression with the dependent variables being: the weekly probability of PRRSV ELISA positivity, and the weekly probability of PRRSV PCR positivity, respectively. The weekly probability of PRRSV PCR positivity decreased during the PVCAD outbreak (OR=0.66, P=0.01). The weekly probability of PRRSV ELISA positivity was not associated with the PCVAD outbreak. CONCLUSIONS: The results of this study showed that during the PCVAD outbreak in Ontario from December 2004-May 2006, the probability of a positive PRRSV PCR at the AHL decreased. We conclude that when a decrease in test positivity occurs for a known disease, it may suggest that a new disease agent is emerging in the population. Hence, monitoring the test results of commonly used first-order tests for a known disease (e.g. PRRSV) has the potential to be a unique form of syndromic data for the timely identification of novel disease outbreaks in swine populations.

Food safety issues and information needs: an online survey of public health inspectors.

In the study described in this article, the authors investigated the perceptions and needs of public health inspectors (PHIs) in the province of Ontario, Canada, with regard to food safety issues and information resources. A cross-sectional online survey of 239 Ontario PHIs was conducted between April and June 2009. Questions pertained to their perceptions of key food safety issues and foodborne pathogens, knowledge confidence, available resources, and resource needs. All respondents rated time-temperature abuse, inadequate hand washing, and cross contamination as important food safety issues. Salmonella, Campylobacter, and E. coli O157:H7 were pathogens reported to be of concern to 95% of respondents (221/233). Most respondents indicated that they were confident in their knowledge of food safety issues and foodborne pathogens, but wanted a central, online resource for food safety information and ongoing food safety education training for PHIs. The data from the authors' study can be used in the development of information resources targeted to the needs of PHIs involved in food safety.

A description of local pig feeding systems in village smallholder farms of Western Kenya.

We used face-to-face interviews to gather data on pig feeding practices in rural Busia District, Kenya. We visited 164 pig farms three times in the course of the study period. The pigs were weighed in kilograms during the visits. Feeds offered to pigs were described during the interviews. The most frequently fed feedstuffs were; ground maize or "ugali" (88%), kitchen leftovers (83%) and dried fish locally called "omena" (78%). Farmers provided pigs with water separately from the feeds. Sweet potatoes, "ugali" and cassava were available and could serve as good sources of energy for pigs in the district. Fruits and vegetables were also available and could potentially act as good sources of vitamins. Sweet potato vines, "omena" fish and slaughter blood were available and could provide pigs with proteins. The average daily gain (ADG) for pigs ≤ 5 months of age, pigs of 5.1-9.9 months of age and pigs of ≥ 10 months old was 94.5 (± 43), 127 (± 49.8) and 99 (± 92) g, respectively (p = 0.000). This study has outlined the different local pig feeds available in Busia district. We recommend two things: first, additional research on nutrient composition for the identified local feeds, and second, developing and validating simple local feed combinations that would achieve balanced local pig rations.

Seroprevalence of bovine viral diarrhea virus neutralizing antibodies in finisher hogs in Ontario swine herds and targeted diagnostic testing of 2 suspect herds.

A pilot study was initiated to determine the seroprevalence of bovine viral diarrhea virus (BVDV) neutralizing antibodies in finisher hogs in Ontario swine herds, including 2 swine herds with clinical syndromes suspicious of BVDV. No herds were positive for BVDV antibodies by virus neutralization. The 2 swine herds with clinical disease suggestive of pestivirus infection were also negative for antibodies to BVDV in indirect fluorescent antibody assays. Prevalence of BVDV in Ontario swine farms is negligible.

Spread of porcine circovirus associated disease (PCVAD) in Ontario (Canada) swine herds: Part II. Matched case-control study.

BACKGROUND: The emergence of porcine circovirus associated disease (PCVAD) was associated with high mortality in swine populations worldwide. Studies performed in different regions identified spatial, temporal, and spatio-temporal trends as factors contributing to patterns of the disease spread. Patterns consistent with spatial trend and spatio-temporal clustering were already identified in this dataset. On the basis of these results, we have further investigated the nature of local spread in this report. The primary objective of this study was to evaluate risk factors for incidence cases of reported PCVAD. RESULTS: A time-matched case-control study was used as a study design approach, and conditional logistic regression as the analytical method. The main exposure of interest was local spread, which was defined as an unidentified mechanism of PCVAD spread between premises located within 3 kilometers of the Euclidean distance. Various modifications of variables indicative of local spread were also evaluated. The dataset contained 278 swine herds from Ontario originally sampled either from diagnostic laboratory submissions or directly from the target population. A PCVAD case was defined on the basis of the producer's recall. Existence of apparent local spread over the entire study period was confirmed (OR = 2.26, 95% CI: 1.06, 4.83), and was further identified to be time-varying in nature - herds experiencing outbreaks in the later part of the epidemic were more likely than control herds to be exposed to neighboring herds experiencing recent PCVAD outbreaks. More importantly, the pattern of local spread was driven by concurrent occurrence of PCVAD on premises under the same ownership (OREXACTwithin ownership = 25.6, 95% CI: 3.4, +inf; OREXACToutside ownership = 1.3, 95% CI: 0.45, 3.3). Other significant factors included PRRSv status of a herd (OREXACT = 1.9, 95% CI: 1.0, 3.9), after adjusting for geographical location by including the binary effect of the easting coordinate (Easting > 600 km = 1; OREXACT = 1.8, 95% CI: 0.5, 5.6). CONCLUSIONS: These results preclude any conclusion regarding the existence of a mechanism of local spread through airborne transmission or indirectly through contaminated fomites or vectors, as simultaneous emergence of PCVAD could also be a result of concurrent change in contributing factors due to other mechanisms within ownerships.

Spread of porcine circovirus associated disease (PCVAD) in Ontario (Canada) swine herds: Part I. Exploratory spatial analysis.

BACKGROUND: The systemic form of porcine circovirus associated disease (PCVAD), also known as postweaning multisystemic wasting syndrome (PMWS) was initially detected in the early 1990s. Starting in 2004, the Canadian swine industry experienced considerable losses due to PCVAD, concurrent with a shift in genotype of porcine circovirus type 2 (PCV2). Objectives of the current study were to explore spatial characteristics of self-reported PCVAD distribution in Ontario between 2004 and 2008, and to investigate the existence and nature of local spread. RESULTS: The study included 278 swine herds from a large disease-monitoring project that included porcine reproductive and respiratory syndrome (PRRS) virus-positive herds identified by the diagnostic laboratory, and PRRS virus-negative herds directly from the target population. Herds were included if they had growing pigs present on-site and available geographical coordinates for the sampling site. Furthermore, herds were defined as PCVAD-positive if a producer reported an outbreak of circovirus associated disease, or as PCVAD-negative if no outbreak was noted. Spatial trend was investigated using generalized additive models and time to PCVAD outbreak in a herd using Cox's proportional hazard model; spatial and spatio-temporal clustering was explored using K-functions; and location of most likely spatial and spatio-temporal clusters was investigated using scan statistics. Over the study period, the risk of reporting a PCVAD-positive herd tended to be higher in the eastern part of the province after adjustment for herd PRRS status (P = 0.05). This was partly confirmed for spread (Partial P < 0.01). Local spread also appeared to exist, as suggested by the tentative (P = 0.06) existence of spatio-temporal clustering of PCVAD and detection of a spatio-temporal cluster (P = 0.04). CONCLUSIONS: In Ontario, PCVAD has shown a general trend, spreading from east-to-west. We interpret the existence of spatio-temporal clustering as evidence of spatio-temporal aggregation of PCVAD-positive cases above expectations and, together with the existence of spatio-temporal and spatial clusters, as suggestive of apparent local spread of PCVAD. Clustering was detected at small spatial and temporal scales. Other patterns of spread could not be detected; however, survival rates in discrete Ontario zones, as well as a lack of a clear spatial pattern in the most likely spatio-temporal clusters, suggest other between-herd transmission mechanisms.

A qualitative exploration of the perceptions and information needs of public health inspectors responsible for food safety.

BACKGROUND: In Ontario, local public health inspectors play an important frontline role in protecting the public from foodborne illness. This study was an in-depth exploration of public health inspectors' perceptions of the key food safety issues in public health, and their opinions and needs with regards to food safety information resources. METHODS: Four focus group discussions were conducted with public health inspectors from the Central West region of Ontario, Canada during June and July, 2008. A questioning route was used to standardize qualitative data collection. Audio recordings of sessions were transcribed verbatim and data-driven content analysis was performed. RESULTS: A total of 23 public health inspectors participated in four focus group discussions. Five themes emerged as key food safety issues: time-temperature abuse, inadequate handwashing, cross-contamination, the lack of food safety knowledge by food handlers and food premise operators, and the lack of food safety information and knowledge about specialty foods (i.e., foods from different cultures). In general, participants reported confidence with their current knowledge of food safety issues and foodborne pathogens. Participants highlighted the need for a central source for food safety information, access to up-to-date food safety information, resources in different languages, and additional food safety information on specialty foods. CONCLUSIONS: The information gathered from these focus groups can provide a basis for the development of resources that will meet the specific needs of public health inspectors involved in protecting and promoting food safety.

Knowledge of zoonoses among those affiliated with the ontario Swine industry: a questionnaire administered to selected producers, allied personnel, and veterinarians.

Zoonoses are diseases caused by infectious agents that are transmitted from animals to humans. Some zoonoses have been associated with the pig and pork industry. To ensure the safety of pigs and pork and to improve public health it is essential to understand the level of knowledge of those affiliated with the swine industry. The purpose of our study was to assess the knowledge of and attitude toward zoonotic and other microbial hazards among targeted groups of stakeholders associated with the Ontario swine industry. A postal questionnaire was sent to 409 individuals representing producers, veterinarians, and allied industry personnel. The questionnaire included seven dichotomous and Likert-scale type questions on microbial hazards, addressing topics on familiarity, concern, presence, antimicrobial resistance, and knowledge transfer. The overall response rate was 53% (218/409). More respondents were concerned about the zoonotic potential of Salmonella spp. (53-94%) and swine influenza virus (64-75%) than other hazards. The group of veterinarians were more familiar (>89%) with all microbial hazards than other occupation groups. Additionally, antimicrobial resistance was reported as a problem by more (60%) veterinarians than producers (20%). Educational efforts should focus on preferred methods of knowledge transfer (e.g., producer meetings, magazine) to update swine industry personnel about zoonoses in an attempt to improve food safety and public health.

Specialty food safety concerns and multilingual resource needs: an online survey of public health inspectors.

The province of Ontario, Canada, has a highly diverse and multicultural population. Specialty foods (i.e., foods from different cultures) are becoming increasingly available at retail food outlets and foods service establishments across the province; as a result, public health inspectors (PHIs) are increasingly required to assess the safety of foods with which they may be unfamiliar. The aim of this study was to investigate the concerns, perceptions, and self-identified needs of PHIs in Ontario with regard to specialty foods and food safety information resources in languages other than English. A cross-sectional online survey of 239 PHIs was conducted between April and June 2009. The study found that while some food safety information resources were available in languages other than English, fewer than 25% of respondents (56/239) were satisfied with the current availability of these resources. With regard to specialty foods, 60% of respondents (143/239) reported at least one specialty food with which they were not confident about their current food safety knowledge, and 64% of respondents (153/239) reported at least one specialty food with which they were dissatisfied with the current availability of food safety information. Therefore, the development of additional food safety information resources for specialty foods, and food safety resources in additional languages may provide enhanced support to PHIs involved in protecting and promoting a safe food supply.

Management factors associated with farrowing rate in commercial sow herds in Ontario.

The objectives of this study were to determine associations between low farrowing rate and various management factors in sow herds. In 30 sow herds, a management survey, breeding observations, semen evaluation, and semen storage temperature monitoring were completed. Herds with an average farrowing rate of < 85% were classified as low farrowing rate herds while those with an average farrowing rate of > or = 85% were classified as good farrowing rate herds. Low farrowing rate herds were more likely than good farrowing rate herds to move boars into gilt pens for estrus detection, breed a high proportion of sows by artificial insemination (AI) only, start heat detection 3 d post-weaning, wipe the vulva prior to breeding, and use "hands-free" AI devices.

Identification of Illness Uncertainty in Veterinary Oncology: Implications for Service.

Uncertainty has been identified as the central psychological feature of illness experiences, necessitating a variety of coping strategies to effectively manage it and successfully adapt. The purpose of this qualitative study was to determine the expectations of veterinary clients accessing oncology care services at a tertiary referral center for dogs with life-limiting cancer. The study consisted of 43 dog owners participating in 30 independent in-person single and dyadic interviews conducted with standardized open- and closed-ended questions from April to October 2009. Thematic analysis (supplemented with content analysis) was performed on transcripts of the interview discussions. Uncertainty was inadvertently identified as a central theme of the clients' experience. The diagnosis of a serious, life-limiting cancer and its treatment appeared to move clients into a world of uncertainty, which affected their feelings, thoughts, behaviors, attitudes, and personal expectations in relation to their dog, and their expectations of the oncology service. With uncertainty appraised mostly as a danger, clients appeared to employ multiple coping strategies to reduce uncertainty in the effort to adapt to the new reality of living with and caring for a dog with cancer. The need to manage uncertainty influenced their expectations of the service, specifically for information, ongoing relationships, 24-h access, and timely care. Our findings have implications for the delivery of specialty oncology services and for client welfare. When working with owners of dogs with life-limiting cancer, results suggest health care providers can facilitate the management of uncertainty to enhance clients' psychological well-being, thereby supporting clients' successful adaptation to the cancer experience.

The use of epidemiology to enhance production animal research.

The approach to understanding the impact of management and disease in production animal systems has evolved with the advent of both routine on-farm data collection and new analytic epidemiology techniques. Epidemiology provides a tool to describe the host-agent-environment triad and the impact of multiple variables on productivity and health recognized by production animal veterinarians in their day-to-day work. Field trials enable veterinarians to systematically test whether or not a new treatment improves the health of the animal populations in their geographic region and under their production systems. Hypothesis-specific coding techniques, such as hierarchical variables, are used in a systematic manner to understand well-defined biological phenomenon. Clustering at multiple levels has provided the challenges of measuring management changes in each level. Using random effects models allow us to determine the relative importance of each level on the dependent variable. As epidemiologists, we have taken advantage of analytic techniques used in other fields of science. Geo-spatial statistics has been used to understand the clustering and spread of diseases and more recently, to interpret the laboratory findings related to the introduction of an exotic strain of the influenza virus. Dr. Martin, through his work as a veterinary epidemiologist and that of people he has influenced, has been an international leader in promoting the optimal health and productivity of animal populations and of ensuring the safety of foods of animal origin and preventing animal-related disease in humans.

Investigation of exposure to swine influenza viruses in Ontario (Canada) finisher herds in 2004 and 2005.

The epidemiology of influenza in the North American swine population has changed since the emergence of a triple-reassortant H3N2 influenza virus. Although seen previously in North America, the Ontario swine population had likely been free of viruses of the reassortant H3N2 lineage until 2005. The objective of this study was to investigate the frequency and distribution of exposure to H1N1 and H3N2 subtypes in the Ontario finisher pig population prior to and after the H3N2 outbreak that occurred in 2005. This included investigating prevalence and spatial distribution of positive herds, assessing proportion of random variation at different hierarchical levels, and evaluating selected demographic factors and management procedures as potential risk factors. In total, 919 and 978 sera collected in cross-sectional studies from 46 and 49 finisher herds in 2004 and 2005 were tested by a H1N1 subtype-specific and a H3N2 subtype-specific commercial ELISA. For the H1N1 subtype, the point prevalence of positive herds (>3 reactors) was 19.5% and 30.6% in 2004 and 2005, respectively. For the H3N2 subtype the point prevalence of positive herds (>3 reactors) was 6.5% and 40.8% in 2004 and 2005, respectively. Sera from 2004 that were positive on H3N2 ELISA did not cross-react with any of the H3N2 variants used as antigen on a sequential HI test. Only herds positive for H3N2 subtype in 2005 clustered in space (P<0.01). The H1N1 status in 2005 was associated with the H1N1 status in 2004, and with reported distance to the nearest herd. The H3N2 status in 2005 was associated with reported distance to the nearest herd and a type of replacement gilt source. For H3N2, distance seemed to be important even after controlling for type of gilt source. Most variability in seropositivity was between herds with little variability between pens. This study confirms that in 2005, the epidemic H3N2 subtype co-circulated with endemic H1N1 subtype in the Ontario finisher herds. We concluded that in Ontario, the endemic H1N1 subtype was likely maintained through circulation within herds and sites with common flow. Whereas the transmission of epidemic H3N2 subtype was attributed to local spread, which could include different modes of direct, indirect, and airborne transmission. We emphasize the importance of establishing routine monitoring systems that would allow using molecular tools, and maintaining serum banks as a useful resource for retrospective comparisons.

Field trial to determine the impact of providing additional care to litters on weaning weight of pigs.

The purpose of this field trial was to determine if maximal care of pigs from birth until 16 d of age would result in a significant alteration in the survivorship and growth performance of the pigs compared with control pigs born in the same time period. Sows were randomly assigned to treatment group prior to farrowing. Control pigs received the standard, commercial farm care. In maximal care litters, pigs were dried off at farrowing, given a rubber mat in the creep area, and given electrolytes, chilled pigs were warmed and given colostrum or glucose, surgical instruments used for processing were dipped into an antiseptic between pigs, the castration wounds were sprayed with iodine, and sows were fed 3 times rather than twice a day. Pigs that received the maximal care weighed 170 g (+/- 80 g) more at 16 d of age than standard care pigs. Factors that reduced weight at 16 d included having a low birth weight, nursing a gilt or a parity 5-6 sow, nursing in a large litter, being clinically ill or being lame after 3 d of age, being cross-fostered and nursing an ill sow. In general, maximal care did not reduce mortality. Providing maximal care did improve weaning weights and enabled small birth weight pigs to reach 3.7 kg at 16 d of age.