Leptospirosis is a bacterial zoonotic disease of global importance. It is caused by infection with pathogenic Leptopsira species. Leptospirosis encompasses a wide spectrum of clinical or subclinical disease in both humans and animals. In New Zealand (NZ), leptospirosis is considered to be the most important occupational zoonosis. Livestock farming plays an important role as a major occupational risk factor for human leptospirosis and farmed deer is one of the contributing factors. Commercial farming of deer began in NZ in the early 1970s. It remains the world’s largest and most advanced deer farming industry. Leptospirosis in farmed deer can cause illness and possibly sub-clinical production losses. Farmed deer also play an important role in the transmission of leptospirosis by shedding the organisms in their urine, putting both other animals and humans at risk. Leptospira serovars Hardjobovis and Pomona are the most commonly found serovars in this stock group. The first substantial case report of leptospirosis in farmed deer was in the 1980s but it was not until 2006 that a substantial epidemiological study of this disease in farmed deer was reported. The purpose of this research was to improve and extend current knowledge on the epidemiology of leptospirosis on mixedspecies deer farms, to develop and validate a novel molecular diagnostic tool and to enhance understanding of control measures and their outcomes by means of vaccination. A pilot longitudinal seroprevalence survey of leptospirosis on mixed-species deer farms was conducted. Results from this study revealed that leptospiral infection averaged 70% in all species on mixed-species farms in the lower North Island of NZ. Co-grazing with infected sheep and/or cattle was positively associated with deer herd serological status to both serovars Hardjobovis and Pomona which suggests the possibility of inter-species transmission. Results from this study justify further investigation of leptospirosis on mixedspecies farm at the national level. A collaborative study between Massey University and the WHO/FAO/OIE reference laboratory for leptospirosis in Brisbane to investigate for exotic serovars in farmed deer revealed seropositivity to Arborea which has never been found before in NZ. Attempts to isolate Arborea from kidney samples of farmed deer were unsuccessful and require further investigation. Real-time PCR assay was developed and validated against culture as the gold standard for use on deer kidney tissue and urine as a research and diagnostic tool for determining infection, carrier and shedding status of deer. This research revealed that the real-time PCR assay was highly sensitive (sensitivity: 85% for kidney and 96.7% for urine) and specific (specificity: 99.2% for kidney and 100% for urine). It is a useful tool for the rapid and cost-effective detection of pathogenic leptospires in clinical samples. It can also be used to quantify the concentration of leptospires from clinical samples and identify the likely infecting serovar in NZ when adjunct with a DNA sequencing technique. Vaccination control for leptospirosis has proven to be efficacious and likely to be costeffective. Present research has determined the effect of a commercial bivalent leptospiral vaccine (Leptavoid-2, Intervet/Schering-Plough Animal Health Limited, NZ) on leptospiral shedding, growth and reproduction of farmed deer under NZ pastoral conditions. The study was designed to simulate an infection-free herd scenario followed by exposure to natural challenge. Results have shown the potential of vaccine to improve mean weight gain (up to 6.5 kg) and weaning rate (average 6.9%) in infected herds and prevent urinary shedding after natural challenge with Hardjobovis. It also provides the first evidence of adverse subclinical effects on deer production by Hardjobovis alone. A pilot study to investigate the presence and localisation of pathogenic Leptospira in the uterus and foetus of female deer revealed evidence of a foetal infection using real-time PCR. This finding suggests a possible explanation for effects of leptospiral infection on NZ farmed deer reproduction. However, further study is required to justify this proposition. This research has contributed significantly to understanding of epidemiology of leptospirosis in NZ farmed deer, providing objective data to assist producers in decision-making on leptospirosis control. Furthermore, this study has made available a valuable diagnostic resource for future leptospirosis studies, and has provided direction for future research into leptospirosis on farmed deer and mixed-species farms.

This thesis addresses issues related to surveillance for disease in commercial and non-commercial poultry populations. The motivation for this work has largely arisen from the unprecedented outbreaks of highly pathogenic avian influenza (HPAI) H5N1 that have occurred in 52 countries in Asia, Africa and Europe since 2003. A series of studies are presented using data derived from two countries, Vietnam and New Zealand. The two Vietnamese studies provide in-depth epidemiological analyses of the outbreak of HPAI H5N1 from December 2003 to March 2004. The three New Zealand studies deal with issues related to the development of effective surveillance strategies for HPAI — informed both directly and indirectly by the findings from the Vietnamese studies. This approach provides an example of how ‘lessons’ learnt from countries that have experienced large scale infectious disease epidemics can be used to assist in the design of surveillance activities in (as yet) unaffected countries. The descriptive analyses of the 2003 – 2004 outbreak of HPAI H5N1 in Vietnam indicate that the epidemic was seeded simultaneously in the north and south of the country in the later part of 2003 with 87% of provinces affected by February 2004. HPAI risk was concentrated around the Mekong and Red River Deltas. The broad scale spatial distribution of disease is likely to have been associated with regional differences in the poultry farming, trade in poultry, and environmental conditions such as the presence of bodies of water which would support reservoir species for the virus. A Bayesian zero-inflated Poisson regression model was used to quantify the influence of environmental and demographic factors on the spatial distribution of HPAI positive communes. In areas where disease was reported, our results show that HPAI risk was positively associated with the presence of irrigation and negatively associated with elevation. After controlling for these fixed effects, a single large area of elevated risk in the Red River Delta area was identified, presumably arising from similarities in the likelihood of reporting disease or the presence of factors increasing disease transmission and spread. Further investigations to elucidate likely transmission mechanisms, targeting this area of the country, would be a profitable area of future research. The second part of this thesis presents three studies that address issues related to the development of effective surveillance strategies for HPAI in New Zealand. The first was a cross-sectional study to enumerate the prevalence of backyard poultry ownership in two areas (one urban and the other rural) close to a large provincial city in the North Island of New Zealand. The prevalence of poultry ownership was 2% (95% CI 1% – 4%) in the urban area and 19% (95% CI 12% – 30%) in the rural area. The relatively low numbers of land parcels where poultry are present indicates that these areas, in the event of an infectious disease incursion, would be unlikely to pose a risk for spread of infectious agent. A cross-sectional survey of all members of the Poultry Industry Association of New Zealand was conducted in the later half of 2007. Respondents were asked to document contacts made with other enterprises related to feed, live birds and hatching eggs, table eggs and poultry product, and waste litter and manure. Patterns of contact were analysed using social network analyses. Each of the four networks had scale-free properties, meaning that for each movement type there were small numbers of enterprises that had contacts with large numbers of enterprises (potential ‘super-spreaders’ of disease). The presence of an undetected infectious disease in enterprises with super-spreader characteristics increases the likelihood that an epidemic will propagate rapidly through the population, assuming there is a directly proportional relationship between the number of contacts an enterprise makes and the probability that disease will be transferred from one location to another. While the finding that feed suppliers had large numbers of poultry farm contacts in the feed network came as no surprise, what was of greater interest was that there were small numbers of poultry farms that reported off-farm movements of feed. This should serve as an important reminder for disease control authorities: movement (and other) restrictions applied during the course of an animal health emergency should be applied across a range of industry sectors, recognising that some industry participants may practice activities that are not entirely typical for their enterprise type (e.g. poultry farms on-selling feed to other farms). In the absence of perfect and up-to-date network data, knowledge of the characteristics of individual enterprises that render them more likely to be atypical (e.g. size, type, and geographic location) would be of value, since this information could be used to inform a risk based approach to disease surveillance and control. A scenario tree model was developed as an approach for evaluating the effectiveness of New Zealand’s passive surveillance system for HPAI. The model was developed in two stages. In the first, factors thought to influence the geographic distribution of NAI risk of introduction and spread (and therefore surveillance strategy) were combined to create a spatial risk surface. In the second stage, a scenario tree model of the passive surveillance system for NAI was developed using the spatial risk surface and the HPAI surveillance strategy prescribed by Biosecurity New Zealand. The model was most sensitive to farmers reporting the presence of suspected cases of disease. This implies that the sensitivity of the system as a whole stands to increase if the importance of reporting suspicious clinical signs is reiterated to poultry producers. The studies presented in this thesis have presented a range of techniques and methodological approaches that are sufficiently generic to be used in any country to inform the design of surveillance strategies for a variety of animal diseases, not just those of poultry. Although epidemiology, as a discipline, is endoured with a vast range of analytical techniques that can be used to enhance the understanding of factors influencing the spread of disease among animal populations, the quality of data used to support these techniques is often lacking. The challenge in the years ahead, for both developed and developing countries, is to set in place the appropriate infrastructures to collect details of animal populations consistent in quality over time and space.

The principle aim of the current research was to modify the larval development assay (LDA) for use with Cooperia from cattle. A series of experiments were conducted in order to modify the LDA protocol to determine the most appropriate culture media and incubation temperature. These initial experiments concluded that, of the protocols examined, a culture medium of 1/8th the concentration of E. coli (EC) + 1/4th the concentration of yeast extract (YE) as generally used to culture sheep nematodes, at a culture temperature of 18ºC, resulted in the optimum number of Cooperia larvae developed to the third larval stage (L3). However, the number of eggs that developed to L3 was still generally low. A comparison was then made using isolates from a farm with a history of resistance in Cooperia to ivermectin (IV) and benzimidazoles (BZ) and two farms with a history of no resistance in this parasite. These experiments were undertaken using 1/8EC + 1/4YE media protocol and 1/2EC + 1/2YE concentration of the standard culture media for sheep nematodes. These three isolates were cultured at temperature of 18ºC and 25 ºC in the commercially available DrenchRite® 96-well microtitre assay plates which contained BZ, levamisole (LV) and IV in doubling dilutions within an agar matrix. The LD50 values were determined from a dose response curve. The resulting LD50 values were very variable, especially for the IV analogues. There was no obvious difference between the resistant and susceptible farms for the LD50 values of BZ or IV. A secondary aim of this research was to investigate the potential usefulness of the larval feeding inhibition assay (LFIA). This was adopted as published and it was determined it could be used to distinguish between susceptible and resistant Teladorsagia circumcincta with a resistance ratio of at least six. This research concluded that further research is required to fully optimise the LDA for Cooperia in cattle but adequate dose response curves were determined to indicate it struggles to distinguish BZ and IV resistance. The LFIA deserves to be further investigated as it offers some scope to detect ivermectin resistance in cattle nematodes as the dose response curves demonstrated a good repeatability for T. circumcincta from sheep. Comparing LDA and LFIA, both assays seemed to be useful but the latter was considered to have greater potential.

This thesis presents the results of a series of studies on the epidemiology of TB in brushtail possum and domestic cattle populations in New Zealand. The first set of studies provides an analysis of the results of routine TB testing carried out in the Featherston area from July 1980 to June 2004. The median annual incidence rate of TB reduced from 4.7 cases per 1000 cattle-years at risk for the period 1986 to 1991 to 1.8 cases per 1000 cattle-years at risk for the period 1992 to 2003, coincident with the use of poisoning to control possums in the surrounding forest park (a major possum habitat area). We identified clusters of cattle TB cases adjacent to the forest park and found no evidence of spatio-temporal interaction of TB risk among farms. Our findings support the hypothesis that possums living in the forest park are a source of bovine TB in this area and that farm-to-farm transmission was not an important mechanism of infection spread. A mixed-effects Poisson regression model was developed to investigate the influence of farm-level covariates on the number of cattle confirmed with TB. The model showed that, despite intensification of possum control activities, proximity to forest parks remained a significant predictor of the number of confirmed TB cases per farm per year. Our analyses identified a significant, 3-fold increase in TB risk in dairy cattle relative to beef conditional on the size of local possum habitat, and confirmed the positive influence of cattle population size and the presence of previous infection status as a determinant of the number of confirmed TB cases per farm per year. The second set of studies investigates details of capture events recorded during a longitudinal, capturemark- recapture study of possums in a 22-hectare study site near Castlepoint, from April 1989 to August 1994. Social network analyses were used to identify contact patterns and to estimate the influence of contact on R0 for bovine TB. The average number of contacts per possum ranged from 20 to 26 per year. We estimated that TB would spread if an average of between 1.94 and 1.97 infective contacts occured per year per infected possum. We evaluated the effect of sex, habitat and contact behaviour of 26 postmortem confirmed TB cases in possums with those of 104 matched controls. Unit increases in the number of infected contacts increased the odds of TB infection by 2.61 (95% CI 1.29 – 5.29, P <0.01). Our results show that individual contact behaviour is a determinant of the presence of TB foci within this population and challenge the hypothesis that contact with many individuals increases the probability of infection. A model to predict spatial variation in possum abundance was developed using a Geographic Information System. Details of possum capture events were obtained from 157 10-trap lines distributed within 42 randomly located transects at Molesworth Station. Two GIS-based models were developed to predict the number of possums caught per line using Poisson regression techniques. The first model used remotely sensed environmental data; the second used a combination of remotely sensed and fine-scale data. Both models provided adequate predictive ability with Pearson correlation coefficients greater than 60%. We conclude that the prediction maps produced from this model provide a useful decision support tool for possum control managers. These results have implications for the management of TB in this area of New Zealand, providing the information that will allow effective control activities to be applied at significantly lower cost.

Lead is a highly toxic metal that has been used by humans for over 2000 years. Over this time it has become increasingly apparent that despite its usefulness, lead is one of the most highly toxic substances known to man. Current research into lead exposure of humans focuses on low-level chronic exposure and its effects on learning and behaviour. However, investigations into lead exposure of wildlife are still focussed on mortalities, particularly of waterfowl and raptors, with little known about low-level exposures or the effects on other species. This study examines the exposure of free-ranging kea (Nestor notabilis) from the Aoraki/ Mt Cook village and national park, takahe (Porphyrio hochstetteri) from Tiritiri Matangi, Kapiti and Mana Islands, and the lead associated syndrome of clenched-claw paralysis and leg paresis in harriers (Circus approximans) in New Zealand. Thirty-eight kea had detectable blood lead with concentrations ranging from 0.028 mg/L to 3.43 mg/L (mean = 0.428 mg/L ± 0.581). Analysis of tissue samples found that seven of 15 birds died with elevated tissue lead. Lead exposure may be an important contributing factor in kea mortality. As a result of these findings, lead abatement in areas frequented by kea is being considered. Eighteen of 45 takahe had detectable blood lead concentrations ranging from 0.015 mg/L to 0.148 mg/L (mean = 0.028 mg/L ± 0.042). Analysis of tissue samples from offshore island and Murchison Mountains birds found that all had detectable lead. Despite levels of lead exposure in the population being low and unlikely to result in overt clinical signs, it is widespread and there may be significant exposure of birds living around old buildings. An investigation into the clinical signs, pathology and response to treatment of clenched-claw paralysis and leg paresis in wild harriers was carried out. Harriers with clenched feet had significantly higher blood lead concentrations than those without. In conclusion, lead is a major factor in the expression of this clinical syndrome but other factors not yet identified are playing a role. This study demonstrates that lead is widespread in the New Zealand environment exposing a diverse range of avifauna, and has made some progress towards exploring some of its effects on health and survival.

This thesis presents two studies that form the basis of the Samoan Ministry of Agriculture and Fisheries’ (MAF) recent efforts to enhance its animal disease surveillance capacity. The first study investigated a method of enhancing the surveillance value of veterinary case data collected by the MAF’s Animal Health Service, which provides the only veterinary service for livestock in the country, through temporal analysis of cases and syndromes by species. Threshold levels generated from 3-monthly moving averages combined over 3 years of veterinary case data were used to identify unusually high numbers of cases and the cause of these unusual events were investigated. Further, the analysis of data in the system identified gaps in the coverage of the Animal Health Service which helped identify alternative methods for conducting surveillance in these areas using the Crops Division advisory officers. The objective of the second study was to identify if the veterinary case data collected by the Animal Health Service represented pig health problems in the general population. Reproduction and mortality patterns were compared on a group of 10 holdings that were regularly attended by the veterinary staff and 13 holdings that did not utilise the Animal Health Service. The performance of these holdings, measured in liveborn piglets per sow year and pre-weaning and post-weaning mortality were compared given their status as client or non-client of the service and their exposure to various management factors like confinement, protein supplementation, frequency of feeding, management time per sow per day, the use of improved or exotic breeds, the extent of commercial activity and, in the case of piglets their season of birth (rainy or dry season). The mean number of sows per herd was 6, producing a mean litter size of 6.1 piglets with a mean interfarrowing interval of 235 days. The median pre-weaning mortality per litter was 0 and a median of 1 piglet per litter was used for productive purposes (consumed, gifted or sold) at a median age of 153 days. It was found that the greatest influence on productivity in these holdings was nutrition. Sow productivity (in terms of liveborn piglets per sow year and pre-weaning survival) was best in the non-client, free range herds that did not provide protein supplementation (but whose feeding was unrestricted due to their freedom to roam and scavenge) and worst in client and non-client herds that were confined and not given protein supplementation (due to restricted and underfeeding). The mortality of pigs postweaning was significantly higher if they were free roaming, due to their loss to predation, theft and being hit by car. The study showed that the health status of pigs was better on holdings that did not use the Animal Health Service compared with those that did.

This thesis presents two studies that form the basis of the Samoan Ministry of Agriculture and Fisheries’ (MAF) recent efforts to enhance its animal disease surveillance capacity. The first study investigated a method of enhancing the surveillance value of veterinary case data collected by the MAF’s Animal Health Service, which provides the only veterinary service for livestock in the country, through temporal analysis of cases and syndromes by species. Threshold levels generated from 3-monthly moving averages combined over 3 years of veterinary case data were used to identify unusually high numbers of cases and the cause of these unusual events were investigated. Further, the analysis of data in the system identified gaps in the coverage of the Animal Health Service which helped identify alternative methods for conducting surveillance in these areas using the Crops Division advisory officers. The objective of the second study was to identify if the veterinary case data collected by the Animal Health Service represented pig health problems in the general population. Reproduction and mortality patterns were compared on a group of 10 holdings that were regularly attended by the veterinary staff and 13 holdings that did not utilise the Animal Health Service. The performance of these holdings, measured in liveborn piglets per sow year and pre-weaning and post-weaning mortality were compared given their status as client or non-client of the service and their exposure to various management factors like confinement, protein supplementation, frequency of feeding, management time per sow per day, the use of improved or exotic breeds, the extent of commercial activity and, in the case of piglets their season of birth (rainy or dry season). The mean number of sows per herd was 6, producing a mean litter size of 6.1 piglets with a mean interfarrowing interval of 235 days. The median pre-weaning mortality per litter was 0 and a median of 1 piglet per litter was used for productive purposes (consumed, gifted or sold) at a median age of 153 days. It was found that the greatest influence on productivity in these holdings was nutrition. Sow productivity (in terms of liveborn piglets per sow year and pre-weaning survival) was best in the non-client, free range herds that did not provide protein supplementation (but whose feeding was unrestricted due to their freedom to roam and scavenge) and worst in client and non-client herds that were confined and not given protein supplementation (due to restricted and underfeeding). The mortality of pigs postweaning was significantly higher if they were free roaming, due to their loss to predation, theft and being hit by car. The study showed that the health status of pigs was better on holdings that did not use the Animal Health Service compared with those that did.

This thesis presents two studies that form the basis of the Samoan Ministry of Agriculture and Fisheries’ (MAF) recent efforts to enhance its animal disease surveillance capacity. The first study investigated a method of enhancing the surveillance value of veterinary case data collected by the MAF’s Animal Health Service, which provides the only veterinary service for livestock in the country, through temporal analysis of cases and syndromes by species. Threshold levels generated from 3-monthly moving averages combined over 3 years of veterinary case data were used to identify unusually high numbers of cases and the cause of these unusual events were investigated. Further, the analysis of data in the system identified gaps in the coverage of the Animal Health Service which helped identify alternative methods for conducting surveillance in these areas using the Crops Division advisory officers. The objective of the second study was to identify if the veterinary case data collected by the Animal Health Service represented pig health problems in the general population. Reproduction and mortality patterns were compared on a group of 10 holdings that were regularly attended by the veterinary staff and 13 holdings that did not utilise the Animal Health Service. The performance of these holdings, measured in liveborn piglets per sow year and pre-weaning and post-weaning mortality were compared given their status as client or non-client of the service and their exposure to various management factors like confinement, protein supplementation, frequency of feeding, management time per sow per day, the use of improved or exotic breeds, the extent of commercial activity and, in the case of piglets their season of birth (rainy or dry season). The mean number of sows per herd was 6, producing a mean litter size of 6.1 piglets with a mean interfarrowing interval of 235 days. The median pre-weaning mortality per litter was 0 and a median of 1 piglet per litter was used for productive purposes (consumed, gifted or sold) at a median age of 153 days. It was found that the greatest influence on productivity in these holdings was nutrition. Sow productivity (in terms of liveborn piglets per sow year and pre-weaning survival) was best in the non-client, free range herds that did not provide protein supplementation (but whose feeding was unrestricted due to their freedom to roam and scavenge) and worst in client and non-client herds that were confined and not given protein supplementation (due to restricted and underfeeding). The mortality of pigs postweaning was significantly higher if they were free roaming, due to their loss to predation, theft and being hit by car. The study showed that the health status of pigs was better on holdings that did not use the Animal Health Service compared with those that did.

This thesis presents two studies that form the basis of the Samoan Ministry of Agriculture and Fisheries’ (MAF) recent efforts to enhance its animal disease surveillance capacity. The first study investigated a method of enhancing the surveillance value of veterinary case data collected by the MAF’s Animal Health Service, which provides the only veterinary service for livestock in the country, through temporal analysis of cases and syndromes by species. Threshold levels generated from 3-monthly moving averages combined over 3 years of veterinary case data were used to identify unusually high numbers of cases and the cause of these unusual events were investigated. Further, the analysis of data in the system identified gaps in the coverage of the Animal Health Service which helped identify alternative methods for conducting surveillance in these areas using the Crops Division advisory officers. The objective of the second study was to identify if the veterinary case data collected by the Animal Health Service represented pig health problems in the general population. Reproduction and mortality patterns were compared on a group of 10 holdings that were regularly attended by the veterinary staff and 13 holdings that did not utilise the Animal Health Service. The performance of these holdings, measured in liveborn piglets per sow year and pre-weaning and post-weaning mortality were compared given their status as client or non-client of the service and their exposure to various management factors like confinement, protein supplementation, frequency of feeding, management time per sow per day, the use of improved or exotic breeds, the extent of commercial activity and, in the case of piglets their season of birth (rainy or dry season). The mean number of sows per herd was 6, producing a mean litter size of 6.1 piglets with a mean interfarrowing interval of 235 days. The median pre-weaning mortality per litter was 0 and a median of 1 piglet per litter was used for productive purposes (consumed, gifted or sold) at a median age of 153 days. It was found that the greatest influence on productivity in these holdings was nutrition. Sow productivity (in terms of liveborn piglets per sow year and pre-weaning survival) was best in the non-client, free range herds that did not provide protein supplementation (but whose feeding was unrestricted due to their freedom to roam and scavenge) and worst in client and non-client herds that were confined and not given protein supplementation (due to restricted and underfeeding). The mortality of pigs postweaning was significantly higher if they were free roaming, due to their loss to predation, theft and being hit by car. The study showed that the health status of pigs was better on holdings that did not use the Animal Health Service compared with those that did.

This thesis presents two studies that form the basis of the Samoan Ministry of Agriculture and Fisheries’ (MAF) recent efforts to enhance its animal disease surveillance capacity. The first study investigated a method of enhancing the surveillance value of veterinary case data collected by the MAF’s Animal Health Service, which provides the only veterinary service for livestock in the country, through temporal analysis of cases and syndromes by species. Threshold levels generated from 3-monthly moving averages combined over 3 years of veterinary case data were used to identify unusually high numbers of cases and the cause of these unusual events were investigated. Further, the analysis of data in the system identified gaps in the coverage of the Animal Health Service which helped identify alternative methods for conducting surveillance in these areas using the Crops Division advisory officers. The objective of the second study was to identify if the veterinary case data collected by the Animal Health Service represented pig health problems in the general population. Reproduction and mortality patterns were compared on a group of 10 holdings that were regularly attended by the veterinary staff and 13 holdings that did not utilise the Animal Health Service. The performance of these holdings, measured in liveborn piglets per sow year and pre-weaning and post-weaning mortality were compared given their status as client or non-client of the service and their exposure to various management factors like confinement, protein supplementation, frequency of feeding, management time per sow per day, the use of improved or exotic breeds, the extent of commercial activity and, in the case of piglets their season of birth (rainy or dry season). The mean number of sows per herd was 6, producing a mean litter size of 6.1 piglets with a mean interfarrowing interval of 235 days. The median pre-weaning mortality per litter was 0 and a median of 1 piglet per litter was used for productive purposes (consumed, gifted or sold) at a median age of 153 days. It was found that the greatest influence on productivity in these holdings was nutrition. Sow productivity (in terms of liveborn piglets per sow year and pre-weaning survival) was best in the non-client, free range herds that did not provide protein supplementation (but whose feeding was unrestricted due to their freedom to roam and scavenge) and worst in client and non-client herds that were confined and not given protein supplementation (due to restricted and underfeeding). The mortality of pigs postweaning was significantly higher if they were free roaming, due to their loss to predation, theft and being hit by car. The study showed that the health status of pigs was better on holdings that did not use the Animal Health Service compared with those that did.