Isolation of [Actinobacillus] rossii from an aborted piglet.

CASE REPORT: This report describes an investigation into the cause of abortions on a commercial pig farm in Victoria in October 2015 in which six sows aborted over a 2-month period. Four of the abortions occurred in the 3 weeks prior to the sows' anticipated farrowing dates and the other two occurred in the second trimester of pregnancy. An analysis of farm data showed that the abortion rate in the previous 12 months (2014-15) was more than twice that of the previous 2 years (1.2% vs 0.5%). Parity appeared not to be a risk factor for abortions. There were no other indicators of reproductive failure on the farm and there were no obvious clinical signs of disease in affected sows. Placenta and aborted fetuses for postmortem analysis were collected while one of the sows was aborting. The only gross abnormality detected in piglets was reddening over the skin. On gross examination the surfaces of the placentas appeared diffusely thickened and 'furry'. Histological examination of fixed placenta from one of two piglets showed a severe, acute, multifocal, necrosuppurative placentitis. Gram staining of a histological section of the placenta revealed abundant Gram-negative short bacilli, consistent with Pasteurella-Actinobacillus spp. A sample of stomach contents from one piglet yielded a profuse predominant growth of bacteria described as Pseudomonas-like. This organism was subsequently identified using 16sRNA sequencing to have 98% homology with [Actinobacillus] rossii. CONCLUSION: This is the first reported case of [A.] rossii isolated from an aborted pig's stomach in Australia.

Industry opinion on the likely routes of introduction of highly pathogenic porcine reproductive and respiratory syndrome into Australia from south-east Asia.

OBJECTIVE: To assess industry expert opinion on the likely occurrence of entry and exposure routes relevant to a potential incursion of highly pathogenic (HP) porcine reproductive and respiratory syndrome (PRRS) virus from south-east Asia to Australia. DESIGN: Expert opinion elicitation of pig-industry stakeholders using a face-to-face questionnaire. RESULTS: Pig industry experts identified exposure routes involving the disposal of food waste to have the highest probability of occurrence. They were also concerned about the exposure of commercial pigs to humans acting as fomites of PRRS virus, and to feed and additives imported from south-east Asia. They did not consistently agree on the probability of occurrence of entry routes. CONCLUSION: This study demonstrated that the expert elicitation technique was useful in rapidly assessing opinion from a large group of pig industry experts regarding exposure of pigs in Australia to HP-PRRS virus. The results of this survey were used to direct a risk assessment of an incursion of HP-PRRS.

On-farm characteristics and biosecurity protocols for small-scale swine producers in eastern Australia.

Pigs are considered high risk for the introduction and spread of foot and mouth disease (FMD) in Australia. Facilities where animals from different origins are commingled, such as saleyards, pose a high risk for disease spread. Sound on-farm management practices and biosecurity protocols are the first line of defence against a potential on-farm disease outbreak. This study evaluated the practices of 104 producers (vendors who sold pigs and purchasers of live pigs for grow-out) who traded pigs at 6 peri-urban and rural saleyards in eastern Australia. Specifically, management and on-farm biosecurity practices were assessed using an in-depth questionnaire. Univariable and multivariable logistic regression analyses were used to investigate (1) producer associations: producer type, State, motivation to keep pigs, farm type, gender, years having owned pigs, and the acquisition of formal livestock qualifications; and (2) pig associations: herd size, housing, management (husbandry and feeding) practices and biosecurity (including pig movement) practices. Backyard operations (<20 sows) were undertaken by 60.6% of participants, followed by small-scale pig operations (28.8%; 21-100 sows). Few producers (16.3%) reported residing in close proximity (<5 km) to commercial operations; however, less rural producers had neighbouring hobby pig operations within 5 km of their property (P=0.033). Motivation for keeping pigs was significantly associated with a number of biosecurity practices. Producers who kept pigs for primary income were more likely to provide footwear precautions (P=0.007) and ask visitors about prior pig contacts (P=0.004). Approximately 40% of backyard and small-scale producers reported not having any quarantine practices in place for incoming pigs, compared to only 9.1% among larger producers. The main reasons cited for not adopting on-farm biosecurity practices in this study included having no need on their property (43.1%) and a lack of information and support (by the industry and/or authorities; 18.5%). Up to three-quarters of all producers maintained an open breeding herd, regularly introducing new pigs to the main herd. Saleyards are an important source of income for backyard and small-scale producers as well as an important risk factor for the introduction and dissemination of endemic and emerging animal diseases. Differing management and biosecurity practices as well as the motivations of these producers keeping pigs in small numbers and trading pigs at saleyards need to be taken into account in the development of successful biosecurity extension programmes for this sector of the Australian pork industry.

Investigating risk factors and possible infectious aetiologies of mummified fetuses on a large piggery in Australia.

OBJECTIVE: To investigate risk factors and potential infectious aetiologies of an increased mummification rate (>2%) identified over time on a 1200-sow farrow-to-finish farm in Australia. METHODS: Association of potential non-infectious risk factors and the mummification rate was investigated using 15 years of breeding herd data (40,940 litters) and logistic regression analysis. Samples from a limited number of mummified fetuses were taken to identify potential infectious aetiologies (porcine parvovirus, Leptospira pomona, porcine circovirus type 2, Bungowannah virus and enterovirus). RESULTS: Logistic regression analysis suggested that the mummification rate was significantly associated with sow breed and parity, year and total born and stillborn piglets per litter. The mummification rate was lower (P < 0.001) in Landrace (3.4%) and Large White (2.6%) sows than in Duroc sows (4.9%). Gilts (2.9%) had a lower (P < 0.001) mummification rate than older sows. The mummification rate increased with total born litter size and decreased with the number of stillborn piglets (P < 0.001). A clustering effect within individual sows was identified, indicating that some sows with mummified fetuses in a litter were more likely to have repeated mummifications in subsequent litters. No infectious agents were identified in the samples taken. CONCLUSION: Results from this study suggest that the increased mummification rate identified over time on this farm is likely to be a non-infectious multifactorial problem predisposing the occurrence of mummification. Further research is required to better understand the pathophysiology of mummification and the role that different non-infectious factors play in the occurrence of mummified fetuses.

Managing animal wellbeing: a preliminary survey of pig farmers.

OBJECTIVES: To gather information on producers' perceptions and management strategies towards the detection, alleviation of pain and management of sick, injured and heat-stressed pigs. METHODS: A total of 16 Victorian pig farmers completed a face-to-face questionnaire consisting of 9 open and 26 closed questions regarding their detection and management of sick, injured and heat-stressed pigs and their perceptions of pigs' tolerance to pain. RESULTS: We identified 15 behavioural and physiological indicators of pain and heat stress. Treatment records were kept more often for weaned progeny and lactating sows than for piglets and mated sows. Most producers felt that pigs suffered little pain from routine husbandry procedures and that pain relief was not warranted in those situations. Castration at 10 days of age was the only procedure considered by producers to be very painful. There were inconsistencies in approaches to treating pigs in three case studies of animals with sickness or injury of varying severity. Meloxicam was stated as the most common anti-inflammatory drug used on-farm. A small proportion of farmers incorrectly identified antibiotics as anti-inflammatory drugs. All producers had at least one cooling system in place for preventing heat stress in pigs. CONCLUSIONS: The farmers in this survey group generally relied on behavioural changes in pigs to signal pain and heat stress. Although producers kept treatment records and used hospital pens for compromised pigs, our results suggest that the monitoring of pigs' recovery could be improved. Producers generally have a good understanding of the use of anti-inflammatory drugs to aid recovery of pigs.

Import risk assessment incorporating a dose-response model: introduction of highly pathogenic porcine reproductive and respiratory syndrome into Australia via illegally imported raw pork.

Highly pathogenic porcine reproductive and respiratory syndrome (PRRS) has spread through parts of south-east Asia, posing a risk to Australia. The objective of this study was to assess the probability of infection of a feral or domestic pig in Australia with highly pathogenic PRRS following ingestion of illegally imported raw pork. A conservative scenario was considered in which 500 g of raw pork was imported from the Philippines into Australia without being detected by border security, then discarded from a household and potentially accessed by a pig. Monte Carlo simulation of a two-dimensional, stochastic model was used to estimate the probability of entry and exposure, and the probability of infection was assessed by incorporating a virus-decay and mechanistic dose-response model. Results indicated that the probability of infection of a feral pig after ingestion of raw meat was higher than the probability of infection of a domestic pig. Sensitivity analysis was used to assess the influence of input parameters on model output probability estimates, and extension of the virus-decay and dose-response model was used to explore the impact of different temperatures and time from slaughter to ingestion of the meat, different weights of meat, and the level of viraemia at slaughter on the infectivity of meat. Parameters with the highest influence on the model output were the level of viraemia of a pig prior to slaughter and the probability of access by a feral pig to food-waste discarded on property surrounding a household. Extension of the decay and dose-response model showed that small pieces of meat (10 g) from a highly pathogenic PRRS viraemic pig could contain enough virus to have a high probability of infection of a pig, and that routes to Australia by sea or air from all highly pathogenic PRRS virus endemic countries were of interest dependent on the temperature of the raw meat during transport. This study highlighted the importance of mitigation strategies such as disposal of food-waste from international traffic as quarantine waste, and the need for further research into the probability of access to food-waste on properties by feral pigs.

Building a picture: Prioritisation of exotic diseases for the pig industry in Australia using multi-criteria decision analysis.

Diseases that are exotic to the pig industry in Australia were prioritised using a multi-criteria decision analysis framework that incorporated weights of importance for a range of criteria important to industry stakeholders. Measurements were collected for each disease for nine criteria that described potential disease impacts. A total score was calculated for each disease using a weighted sum value function that aggregated the nine disease criterion measurements and weights of importance for the criteria that were previously elicited from two groups of industry stakeholders. One stakeholder group placed most value on the impacts of disease on livestock, and one group placed more value on the zoonotic impacts of diseases. Prioritisation lists ordered by disease score were produced for both of these groups. Vesicular diseases were found to have the highest priority for the group valuing disease impacts on livestock, followed by acute forms of African and classical swine fever, then highly pathogenic porcine reproductive and respiratory syndrome. The group who valued zoonotic disease impacts prioritised rabies, followed by Japanese encephalitis, Eastern equine encephalitis and Nipah virus, interspersed with vesicular diseases. The multi-criteria framework used in this study systematically prioritised diseases using a multi-attribute theory based technique that provided transparency and repeatability in the process. Flexibility of the framework was demonstrated by aggregating the criterion weights from more than one stakeholder group with the disease measurements for the criteria. This technique allowed industry stakeholders to be active in resource allocation for their industry without the need to be disease experts. We believe it is the first prioritisation of livestock diseases using values provided by industry stakeholders. The prioritisation lists will be used by industry stakeholders to identify diseases for further risk analysis and disease spread modelling to understand biosecurity risks to this industry.

Identifying and measuring stakeholder preferences for disease prioritisation: A case study of the pig industry in Australia.

We describe stakeholder preference modelling using a combination of new and recently developed techniques to elicit criterion weights to incorporate into a multi-criteria decision analysis framework to prioritise exotic diseases for the pig industry in Australia. Australian pig producers were requested to rank disease scenarios comprising nine criteria in an online questionnaire. Parallel coordinate plots were used to visualise stakeholder preferences, which aided identification of two diverse groups of stakeholders - one group prioritised diseases with impacts on livestock, and the other group placed more importance on diseases with zoonotic impacts. Probabilistic inversion was used to derive weights for the criteria to reflect the values of each of these groups, modelling their choice using a weighted sum value function. Validation of weights against stakeholders' rankings for scenarios based on real diseases showed that the elicited criterion weights for the group who prioritised diseases with livestock impacts were a good reflection of their values, indicating that the producers were able to consistently infer impacts from the disease information in the scenarios presented to them. The highest weighted criteria for this group were attack rate and length of clinical disease in pigs, and market loss to the pig industry. The values of the stakeholders who prioritised zoonotic diseases were less well reflected by validation, indicating either that the criteria were inadequate to consistently describe zoonotic impacts, the weighted sum model did not describe stakeholder choice, or that preference modelling for zoonotic diseases should be undertaken separately from livestock diseases. Limitations of this study included sampling bias, as the group participating were not necessarily representative of all pig producers in Australia, and response bias within this group. The method used to elicit criterion weights in this study ensured value trade-offs between a range of potential impacts, and that the weights were implicitly related to the scale of measurement of disease criteria. Validation of the results of the criterion weights against real diseases - a step rarely used in MCDA - added scientific rigour to the process. The study demonstrated that these are useful techniques for elicitation of criterion weights for disease prioritisation by stakeholders who are not disease experts. Preference modelling for zoonotic diseases needs further characterisation in this context.

Demographic and production practices of pig producers trading at saleyards in eastern Australia.

OBJECTIVE: To gather information on the demographics, motivations, marketing strategies and rearing techniques of producers who trade pigs at livestock markets in eastern Australia. METHODS: A 2-page postal survey was administered to 815 pig producers trading pigs at six livestock markets in eastern Australia. Preliminary demographic and managerial practices were qualitatively and quantitatively determined. Logistic regression analysis was used to provide an insight to those practices that could pose a risk for exotic disease introduction and/or spread. RESULTS: A response rate of 68.7% (505 survey questionnaires) was achieved. Most respondents (73.1%) resided in regional areas and 65.5% of these were classed as 'small-scale' (<100 sows). Herd size was significantly (P < 0.0001) associated with the use of veterinary services, with smaller herds less likely to consult a veterinarian. In addition, peri-urban producers (24.8%) tended (P = 0.051) to contact veterinarians more frequently than regional producers (15.2%). Motivations for keeping pigs differed by herd size, nationality and producer type. One-third of respondents trading pigs used more than one method to market pigs, with marketing strategies differing by herd size. Producers with smaller herd sizes kept pigs as a secondary source of income, as a hobby or for home consumption (P < 0.0001). CONCLUSION: Key risk areas for exotic disease introduction and spread identified in this study included lack of veterinary contact, motivations for keeping pigs other than financial, marketing pigs privately with no formal transaction documentation and the co-production of pigs with ruminant and domestic bird species.

Seasonal variation in the ovarian function of sows.

The modern domestic sow exhibits a period of impaired reproductive performance known as seasonal infertility during the late summer and early autumn months. A reduction in farrowing rate due to pregnancy loss is the most economically significant manifestation of this phenomenon. Presently, little is known of the aetiology of seasonal pregnancy loss in the pig. Recent findings represent a major advancement in the understanding of sow reproductive physiology and implicate poor oocyte developmental competence as a contributing factor to pregnancy loss during the seasonal infertility period. It has also been demonstrated that ovarian activity is depressed during the seasonal infertility period. The reduction in oocyte quality is associated with decreased levels of progesterone in follicular fluid during final oocyte maturation in vivo. The recent identification of sow-specific risk factors, such as parity for late pregnancy loss, should improve breeding herd efficiency by allowing producers to tailor management interventions and/or culling protocols that target animals identified as having a greater risk of late pregnancy loss during the seasonal infertility period.

Providing supplemental milk to piglets preweaning improves the growth but not survival of gilt progeny compared with sow progeny.

Gilt progeny have lighter weaning weights and greater postweaning medication and mortality rates compared with the progeny of older parity sows. Because weaning weight has been positively correlated with postweaning survival, this study aimed to determine whether the provision of supplemental milk preweaning could improve weaning weight and subsequent weights as well as postweaning survival of gilt progeny. The study was replicated in summer and winter as the effects of supplemental milk were expected to vary with season. The progeny of 80 gilts (parity 0) and 80 sows (parity 2 to 5) were allocated to both treatments: with or without supplemental milk in these 2 seasons with 5 sheds/season. Litter size was standardized (10 to 11 piglets) and each piglet was weighed at birth, d 21, weaning (4 wk), and 10 wk of age. Medications and mortalities were recorded both preweaning and postweaning. Pigs were housed within treatment groups postweaning, and ADFI and G:F were measured. Gilt progeny were 200 g lighter at birth in both replicates (P < 0.001) and were 500 g lighter at weaning in the winter replicate (P < 0.05) compared with sow progeny. The provision of supplemental milk improved weaning weight for both gilt and sow progeny by 800 g in summer (P < 0.05) and by 350 g in winter (P < 0.05). This improvement in weaning weight had no effect on the incidence of death or disease in milk-supplemented progeny of either gilts or sows (P > 0.05). Supplemental milk disappearance (the daily difference between the volume of milk provided and the residue left in the drinker) was greater in summer than winter (by 130 mL/piglet d(-1); P < 0.05) as were the associated weaning weight benefits. The weaning weights of supplemented gilt progeny reached or exceeded that of nonsupplemented sow progeny. Gilt progeny had greater postweaning mortality (2.6%) and medication rates (6.2%) than sow progeny (1 and 2.2%, respectively; both P < 0.05) in both seasons, but medication rates were greater in winter (7.2%) for both treatment groups than in summer (1.9%; P < 0.05). Gilt progeny also had less postweaning ADFI than sow progeny in winter (528 and 636 g, respectively; P < 0.05) with no dam parity effect on G:F (both P > 0.05). The hypothesis that supplemental milk provision did increase gilt progeny weaning weight was supported (especially in summer) but the supplementation had no effect on postweaning weights and survival. Efforts to improve gilt progeny postweaning growth and survival need to be aimed at improving health and immunity, not just weaning weight.

Use of stakeholder analysis to inform risk communication and extension strategies for improved biosecurity amongst small-scale pig producers.

Extension and communication needs amongst small-scale pig producers, described as pig producers with less than 100 sows, have been previously identified. These producers, who are believed to pose a biosecurity risk to commercial livestock industries, are characterized by a lack of formal networks, mistrust of authorities, poor disease reporting behaviour and motivational diversity, and reliance on other producers, veterinarians and family for pig health and production advice. This paper applies stakeholder identification and analysis tools to determine stakeholders' influence and interest on pig producers' practices. Findings can inform a risk communication process and the development of an extension framework to increase producers' engagement with industry and their compliance with biosecurity standards and legislation in Australia. The process included identification of stakeholders, their issues of concerns regarding small-scale pig producers and biosecurity and their influence and interest in each of these issues. This exercise identified the capacity of different stakeholders to influence the outcomes for each issue and assessed their success or failure to do so. The disconnection identified between the level of interest and influence suggests that government and industry need to work with the small-scale pig producers and with those who have the capacity to influence them. Successful biosecurity risk management will depend on shared responsibility and building trust amongst stakeholders. Flow-on effects may include legitimating the importance of reporting and compliance systems and the co-management of risk. Compliance of small-scale pig producers with biosecurity industry standards and legislation will reduce the risks of entry and spread of exotic diseases in Australia.

The first identified case of pandemic H1N1 influenza in pigs in Australia.

A 300-sow farrow-to-finish herd in New South Wales was infected with influenza pandemic (H1N1) 2009 (H1N1/09) virus in July 2009 and became the first recorded case of influenza in pigs in Australia. The outbreak resulted from human-to-pig transmission. Clinical signs in affected pigs were mild compared with overseas reports of 'classical' swine influenza virus and included coughing and decreased appetite in a small proportion of non-lactating breeding stock, weaners, growers and finishers. A diagnosis of H1N1/09 influenza virus infection was confirmed using a combination of serology (haemagglutination inhibition, blocking enzyme-linked immunosorbent assay) and real-time reverse transcription polymerase chain reaction. Attempts at virus isolation were unsuccessful. Results of a longitudinal study of pigs on this farm suggested that the virus continued to circulate for 9 weeks after the onset of infection, but was not present 6 months later. This report highlights the difficulties in preventing transmission of H1N1/09 influenza virus from infected humans to pigs during a human pandemic.

Evaluation of post-farm-gate passive surveillance in swine for the detection of foot and mouth disease in Australia.

Pigs are considered high risk for the introduction and spread of foot and mouth disease (FMD) in Australia. One of the most likely pathways of introduction of FMD into Australia would be through the illegal importation of FMD-contaminated meat, which is then fed to feral or domestic pigs. Locations where animals from different origins are commingled, such as livestock markets and abattoirs, pose a risk for disease spread. Early detection of exotic diseases at these locations is crucial in limiting the spread of an outbreak. The aims of this study were to evaluate the likelihood of exotic disease detection with current passive disease surveillance activities for pigs at saleyards and abattoirs in eastern Australia, and make recommendations for improving surveillance. Sensitivity (Se) of the current post-farm-gate passive surveillance for detection of exotic diseases was estimated using the scenario tree modelling methodology (Martin et al., 2007a). Four surveillance system components were identified: (i) domestic saleyard, (ii) export saleyard, (iii) domestic abattoir, and (iv) export abattoir. Pig farms were classified according to herd size (Small vs. Large) and subsequently into two risk categories depending on the probability of swill feeding (Swill feeding vs. Not swill feeding). A scenario tree representing the pathways by which infected animals could be detected was developed and the Se of detection in each surveillance system component was estimated. Industry statistics, information on previous exotic disease outbreaks, and interviews with pig producers were used to estimate herd category proportions and the relative risk of swill feeding. Quantitative estimates for probabilities of detection were sourced from State legislation and policies, stakeholder consultation and observational studies at saleyards and abattoirs. Results of a FMD case study showed a Se of detection at a representative location for each surveillance system component during a 2-week period of 0.19 at domestic saleyards, 0.40 at export saleyards, 0.32 at domestic abattoirs and, 0.53 at export abattoirs. This output assumed the country was infected with herd and unit design prevalences of 1% and 30%, respectively. Improving disease awareness of saleyard and abattoir stockmen, increasing the presence of inspectors at these venues and identifying those herds posing a higher risk for FMD introduction, could improve the capacity of the country for early detection of emerging animal diseases.

Seasonal effects on oocyte developmental competence in sows experiencing pregnancy loss.

Recently, oocyte quality in sows culled for reasons unrelated to fertility was found to decline during the period of seasonal infertility. Wean-to-service interval (WSI) has also been associated with pregnancy loss in sows mated during the period of seasonal infertility. The aims of this study were to determine whether WSI and season are associated with changes in oocyte developmental competence in sows experiencing early (before Day 35 of gestation) and late (after Day 35 of gestation) pregnancy loss. Ovaries were collected in pairs from sows sourced from commercial piggeries that were culled for reasons related to infertility after being mated in summer and winter/spring. Sows were grouped according to their pregnancy loss type, their previous WSI and the presence or absence of corpora lutea (CL) on their ovaries. Oocyte developmental competence was assessed following in vitro maturation, artificial activation and parthenote development in vitro. In sows culled for early-pregnancy loss, there was a greater number of CL present on ovaries collected in spring compared to those collected in summer (11.57±3.3 vs. 9.26±0.99; P<0.05). Also, the proportion of oocytes developing to the blastocyst stage was greater in summer than in spring (55.9±5.2% vs. 31.2±6.4%; P<0.05). In sows culled for late-pregnancy loss, a greater proportion of oocytes developed to the blastocyst stage in winter compared with late-spring (64.3±7.0% vs. 34.1±6.6%; P<0.05). In addition, the blastocyst formation rate of oocytes was lower in sows that displayed a WSI≤6 days than in sows that displayed a WSI>6 days (37.8±7.3% vs. 62.2±6.9%; P<0.05). The results of the present study indicate that sows culled for pregnancy loss exhibit seasonal changes in oocyte developmental competence. The mechanism which causes WSI to be prolonged does not appear to result in reduced oocyte developmental competence. While poor oocyte quality and the mechanism that increases WSI may contribute to pregnancy loss during the seasonal infertility period, the findings suggest that these factors are not the main drivers of early and late pregnancy loss throughout the year.

Follicular progesterone levels decrease during the period of seasonal infertility in sows.

Impaired reproductive performance exhibited by the domestic sow during the late summer and early autumn months is referred to as seasonal infertility. This study was carried out to determine whether there are changes in ovarian morphology and follicular steroidogenesis associated with season, which may be associated with seasonal infertility. Ovaries were collected in pairs from sows sourced from two farms and slaughtered 4 days after weaning during winter and summer. The mean progesterone concentration in follicular fluid (FF) collected from small follicles was lower in summer (701.3 ± 115.54 nm) compared with winter (1235.55 ± 164.47 nm; p<0.001). The mean progesterone concentration in the FF of large follicles was also lower in summer (1469.2 ± 156.51 nm) compared with winter (2470.9 ± 169.13 nm; p<0.001). The number of large surface antral follicles (5-8 mm in diameter) on the ovaries recovered from Farm A sows was higher during summer (17.76 ± 0.56) than in winter (15.38 ± 0.54; p<0.05). Similarly, the number of small follicles (3-4 mm in diameter) on Farm A sow ovaries was higher in summer (8.46 ± 0.66) than in winter (4.63 ± 0.53; p<0.001). In contrast, the number of small follicles on the surface of ovaries recovered from Farm B sows was higher during winter (10.17 ± 1.50) than in summer (6.45 ± 1.00; p<0.01). The number of pre-ovulatory follicles (>8 mm in diameter) was also higher in winter (1.23 ± 1.68) when compared to summer (0.51 ± 0.3; p<0.001) on the ovaries of sows from Farm B. The results suggest that there are seasonal differences in follicular steroidogenesis and ovarian dynamics. These findings add support to the theory that altered follicular steroidogenesis and ovarian morphology may possibly be the mechanism behind reduced reproductive performance during the period of seasonal infertility in sows.

Oocyte developmental competence is reduced in sows during the seasonal infertility period.

The modern domestic sow exhibits a period of impaired reproductive performance during the late summer and early autumn months, known as 'seasonal infertility'. A reduction in farrowing rate due to pregnancy loss is the most economically important manifestation of seasonal infertility. The aim of the present study was to determine whether there are changes in oocyte developmental competence associated with season. Ovaries were collected in pairs from sows sourced from commercial piggeries and slaughtered 4 days after weaning during winter and summer-autumn. Following oocyte IVM and parthenogenetic activation, the ability of oocytes from large follicles to form blastocysts was greater in winter (54.94 ± 6.11%) than in summer (21.09 ± 5.59%). During winter, the proportion of oocytes developing to the blastocyst stage from large follicles was significantly higher (54.94 ± 6.11%) than those oocytes from small follicles (23.17 ± 6.02%). There was no effect of season on the proportion of oocytes developing to the blastocyst stage from small follicles. There was no effect of follicle size on blastocyst formation from those oocytes recovered during summer. Blastocysts derived from small follicles during summer had the lowest number of cells (24.25 ± 1.48) compared with blastocysts derived from large follicles during winter (37.5 ± 1.3; P < 0.05). The mean progesterone concentration in follicular fluid collected from small follicles was greater in winter than summer (1235.55 ± 164.47 v. 701.3 ± 115.5 nmol L(-1), respectively; P < 0.001). The mean progesterone concentration in the follicular fluid of large follicles was also greater in winter than in summer (2470.9 ± 169.1 v. 1469.2 ± 156.5 nmol L(-1), respectively; P < 0.001). Regression analysis revealed a positive correlation between progesterone concentration and oocyte developmental competence. The results indicate that porcine oocytes fail to reach their full developmental potential during the period of seasonal infertility, suggesting that the pregnancy losses observed at this time of year may be due to reduced oocyte developmental competence.

Feeding of prohibited substances (swill) to pigs in Australia.

OBJECTIVE: To assess current swill feeding legislation, swill feeding investigation practices by authorities and feeding practices of pig producers who trade via saleyards in eastern Australia in order to determine levels of understanding and conformance related to current swill feeding legislation. METHOD: A three-tiered approach was undertaken to gather information on the feeding of prohibited substances (swill) to pigs in Australia. Firstly, a review of swill feeding legislation was undertaken to highlight the commonalities and inconsistencies between the various state and territory legislations in defining swill. Secondly, agricultural authorities were contacted in each state to gather information on swill feeding investigations undertaken in 2006. Finally, face-to-face interviews were conducted with 106 pig producers who traded pigs at one of six saleyards in eastern Australia to ascertain their knowledge of swill feeding and to determine the feeding practices of this sector of the industry. RESULTS: Areas of concern identified included (1) inconsistencies in the feedstuffs classed as 'swill' among states, (2) the number of producers who had been prosecuted for swill feeding in 2006 (n = 4 of 148 inspections), (3) the low knowledge base of producers who sell pigs at saleyards regarding swill feeding, and (4) the types of feedstuffs provided to pigs marketed at saleyards. CONCLUSION: Our findings highlight the need for a consistent definition for 'swill' across Australian states and for improved awareness of swill feeding among producers, particularly those who market pigs at saleyards.

Prevalence of antibodies to Lawsonia intracellularis in pig herds in Australia.

OBJECTIVE: Proliferative enteropathy (PE) of pigs is caused by Lawsonia intracellularis. Clinical severity appears to depend, at least partly, on the infective dose and strain of L. intracellularis. Serological tests are able to detect subclinical disease. The Bioscreen ELISA for detecting L. intracellularis-specific antibodies is widely used to monitor the circulating antibody status of pigs in Australia, but its sensitivity and specificity have not been reported. The aim of the present study was to measure the seroprevalence of antibodies to L. intracellularis in growing pigs in Australia. METHODS: Test sera were sourced from 1817 serum samples collected from finisher pigs from 63 herds across Australia in 2001, selected from a larger sample of 180 herds to represent the contribution that each herd size makes to the number of pigs produced. The test sera were the most recent collection of pig sera from all states and samples had been stored at -80 degrees C from 2001 until testing was conducted in 2008. Sera were tested using the BioScreen ELISA. RESULTS: All herds tested positive for L. intracellularis-specific antibodies. The mean percentage of positive samples within each herd was 84.2% (range 31.3-100%). CONCLUSIONS: Lawsonia intracellularis is endemic in pig herds in Australia and cost-effective strategies to reduce reliance on antibiotics, such as vaccination and/or all-in/all-out pig flow coupled with cleaning and disinfection of pens, are warranted.

Assessment of current disease surveillance activities for pigs post-farmgate in New South Wales.

OBJECTIVES: Evaluate current disease surveillance activities at saleyards and abattoirs in New South Wales (NSW) in order to establish the prevalence of clinical anomalies in pigs at different sites and to compare the sensitivity of detecting anomalies inside versus outside of pens. PROCEDURE: Routine inspections of pigs by staff and government inspectors were observed at two saleyards and two abattoirs in NSW during three visits over a 2-month period (January 2008-March 2008). All pigs presented for sale or slaughter were examined for 19 clinical anomalies from either the side of the pen or while animals were moving outside the pen, with data being combined to give an assumed 'gold standard'. We compared the prevalence of anomalies among animals at the four sites using logistic regression, as well as the sensitivity of detection of the two inspection methods. RESULTS: Frequency and methodology of routine inspection varied among sites. Of the 7747 pigs inspected, 822 (10.6%) showed at least one clinical anomaly. There was moderate agreement between detecting anomalies in penned pigs versus while being moved. Pigs at one abattoir exhibited significantly fewer anomalies than pigs at the other sites. CONCLUSION: The prevalence of anomalies among pigs at saleyards and abattoirs in NSW was relatively high ( approximately 10%). Weaknesses in current disease surveillance activities for pigs post-farmgate have been identified. Increased regulation, surveillance training and modification of standard operational procedures for inspection have the potential to improve the current system.