Transmission of intestinal helminths in Danish sow herds.

Faecal samples from sows and their litters, all untreated with anthelmintics, were examined in eight sow herds, ranging from very intensive to very traditional management. Four helminth genera were recorded, namely Oesophagostomum sp., Ascaris suum, Trichuris suis and Strongyloides ransomi. The herds with the most intensive management were only infected with A. suum, while the more traditionally managed herds were infected with three or four species. In one herd, the sows showed a small relative increase in the excretion of Oesophagostomum eggs during lactation, but in general there was no consistently observable peri-parturient increase in faecal egg output. Furthermore, faecal examination of 5-12-week-old pigs indicated that sow-to-piglet transmission was important in the traditionally managed herds, while it was negligible in the intensive herds. A seasonal variation in the excretion of Oesophagostomum sp. and A. suum eggs was observed in the youngest pigs in the traditional herds, with the highest faecal egg counts occurring in the summer and autumn. However, this pattern became indistinct during the fattening period and did not exist in the sows, except for A. suum infections in the heavily infected traditional herds. The helminths egg excretion in the intensive herds did not show any seasonal variation.     

Relationship between group A porcine rotavirus and management practices in swine herds in Ontario

A case-control epidemiological study was conducted to determine whether an increased diagnostic rate for group A rotavirus in swine herds in Ontario was associated with specific management factors. The number of new herds tested per year and the proportion of new positive herds increased between 1994 and 1997. Herd size was larger and weaning age was younger in rotavirus-positive herds compared with rotavirus-negative herds. Pigs raised in all-in all-out nurseries were 3.4 times more likely to have a positive group A rotavirus diagnosis than pigs in continuous flow facilities. This study demonstrates that the changes seen in group A rotavirus disease herd status in Ontario are associated with changes in farm management practices, including farm expansion, early weaning, and all-in all-out production.     

Helminth infections in Danish organic swine herds

In nine organic swine herds, faecal excretion and pasture contamination by parasite eggs/larvae were studied in a period from March to October 1999. It was shown that the organic pigs were infected with Ascaris suum (28% of weaners, 33% of fatteners, 4% of sows), Trichuris suis (4% of weaners, 13% of fatteners, <1% of sows) and Oesophagostomum spp. (5% of weaners, 14% of fatteners, 20% of sows) whereas no infections with Hyostrongylus rubidus, Metastrongylus spp. or Strongyloides ransomi were detected. Moreover, no pigs showed clinical signs of infestations with scabies or lice. In the soil samples, very few Trichuris eggs were found throughout the season, whereas Ascaris eggs were found in 14% of the soil samples from sow pastures and in 35% from slaughter pig pastures, with the first infective eggs being recorded in July and the maximum number in August. Infective Oesophagostomum larvae were found in the grass samples in increasing numbers from May to October. Single herd cases of exceptionally high parasite infection levels are described in relation to herd management procedures.     

Locomotive disorders associated with sow mortality in Danish pig herds

Given the increase in sow mortality in Danish pig herds over the last 10 years, we have investigated the causes of spontaneous death and killing of sows, especially those due to locomotive disorders. A total of 265 culled sows (93 spontaneously dead sows and 172 killed sows) from 10 different herds were sent for complete necropsy, and grouped according to primary diagnoses. From 35 of these sows, tissue for histological evaluation and samples for bacteriological cultivation were also collected, and secondary diagnoses and body condition were recorded. The main causes for killing were related to the locomotive system (72%), arthritis (24%) and fractures (16%) being the most frequent lesions. The main causes of spontaneous death were related to the gastrointestinal system and spleen (45%) and the reproductive system (24%). Arthrosis was a secondary diagnosis in 88% of the killed sows and in 92.5% of the spontaneously dead sows. Arcanobacterium pyogenes was the main cause of arthritis. The killed sows had significantly lower body condition compared with spontaneously dead sows. The first two parities and the time around farrowing were associated with the highest mortality in both groups. Hopefully, these observations can guide breeding units attempting to monitor, control and reduce sow mortality.     

Evaluation of producer-recorded causes of preweaning mortality in Danish sow herds

The validity of producer-recorded preweaning mortality causes was evaluated in 31 Danish sow herds. For 1206 piglets producer-recorded preweaning mortality cause was compared with post-mortem diagnosis. The predominant preweaning mortality causes at post-mortem were injury (trauma, lain on, and savaged), miscellaneous (unknown, starvation, illthrift, euthanasia, and low viability), and diarrhoea, with 391, 219, and 119 recordings, respectively. The sensitivity of producer-recorded preweaning mortality causes was generally low, and further analyses showed that the probability of being born alive and the probability of being given ‘a producer diagnosis other than unknown’ were associated with the herd and that a correct producer-recorded mortality cause relative to the post-mortem diagnosis depended on the mortality cause. Rare mortality causes with primarily internal signs tended to be misclassified. The producers often gave ‘a diagnosis other than unknown’ to pigs with a weight at death under 0.75kg and it was often correct. To pigs with a weight at death over 1.75kg, they rarely gave ‘a diagnosis other than unknown’, but when they did it was often correct.     

Risk factors for high sow mortality in French swine herds

Episodes of high sow mortality rates affect profitability of swine farms. However, relevant control actions are difficult to implement. The objective of this study was to identify the risk factors for high levels of sow mortality rate (HM) in French swine herds. A case-control study was carried out in 102 swine herds located in Brittany (western France). Level of sow mortality of a herd was quantified by the annual mortality rate using sow-days as denominator. Fifty-five (53.9%) herds which experienced a sow mortality rate over 5% were classified as HM herds. Logistic regression was used to assess associations of managerial practices and disease prevalence with the odds of HM. High prevalence of urinary tract infections, metritis or lameness were significantly associated with a HM herd status (P < 0.10, OR ranging from 3.4 to 5.2). Multiplying herds were herds at higher risk for sow mortality than commercial farrow-to-finish herds. Providing three meals per day instead of two to dry sows decreased the odds of HM. Feeding plans where the maximum daily amount of feed provided to lactating sows was lower than 8 kg and was reached before 15 d in lactation were related to lower odds of HM (P < 0.10). Average age at weaning of 28 d or more and/or small average litter size at birth (12 piglets or less) were associated with higher odds of experiencing HM.     

Survey of internal parasites in Western Australian pig herds 2. Relationship to anthelmintic usage and parasite control practices

The housing, management and internal parasite control practices used in piggeries in Western Australia was surveyed by interviewing the owner/manager of 100 randomly selected piggeries. At the time of the interview 20 faecal samples were collected from pigs and examined for evidence of internal parasites. Most herds (80%) in which anthelmintics were used, had evidence of nematode infection. Some pig producers were using an anthelmintic that was ineffective against nematode species present while some herds had nematodes that should have been controlled by the anthelmintic being used. Prevalence of nematode infection was higher in pigs run in paddocks than in pigs housed intensively. Washing sows prior to farrowing was associated with a lower prevalence of nematode infection. The findings suggested that pig producers should ensure that the anthelmintic used is effective against the nematodes present in their pigs. It was concluded that administering anthelmintics as a single dose in the feed may not be the most effective method of deworming pigs.     

A seroepidemiological survey of Leptospira bratislava infections in Danish sow herds

A total of 796 sows and gilts from 30 Danish sow herds were examined three times at intervals of 6 weeks for serum antibodies to Leptospira bratislava by the microscopic agglutination technique (MAT) test. The prevalence of seroreactors with positive titer values, 1:100, at the three successive tests were 2.7%, 2.5% and 2.9%; 4.5% of the animals were positive in at least one of the three tests, and 2.2% showed a greater than two-fold rise in titer between two consecutive samplings. Of the 30 herds, 21 (70%) had ever-positive within-herd prevalences in sows and gilts of 4–13%. The risk of a herd having one or more positive sow was positively associated with a herd size of > 141 sows, and distinct regional differences in the prevalence of positive herds were observed. The reproductive performance of the 21 herds with seroreactions was poorer than the performance of the nine herds without positive reactions concerning the variables: ‘days from weaning to last service’ (2.7 days more, P = 0.07), ‘percentage of sows returning to heat’ (4.0 percentage units more, P = 0.03), ‘services per farrowing’ (0.04 more, P = 0.04), ‘farrowing percentage’ (4.3 percentage units lower, P = 0.06), and ‘stillborn pigs per farrowing’ (0.16 more, P = 0.02). No association between the MAT serological status of the herd and the incidence of medical treatments of sows and gilts could be found. A high prevalence and low cumulative incidence of seroreactors was demonstrated in first-parity gilts, followed by a low prevalence and cumulative incidence from parity 2 to 3, and a high prevalence and cumulative incidence at the fifth parity.     

Feline intestinal parasites in Finland: prevalence, risk factors and anthelmintic treatment practices

The aim of this study was to estimate the prevalence of feline intestinal parasites in Finland and to determine the possible risk factors for infection. Altogether 411 feline fecal samples were analyzed with a flotation method to reveal helminth eggs and protozoan oocysts. Of the samples, 402 were also screened for Giardia species antigens with a commercial enzyme-linked immunosorbent assay kit. The cat owners completed a questionnaire. Toxocara cati prevalence was 5.4% and Toxascaris leonina 0.2%. Taenia species eggs were found in 1.5% of the samples and Isospora felis in 0.7%, whilst 3.2% of the samples tested positive for Giardia species antigen. Risk factors for Toxocara/Toxascaris species infection included being a non-pedigree cat, having access to the outdoors, living outside of the cities and receiving home-made food. Pedigree cats were at greater risk of contracting Giardia duodenalis. The majority of the cat owners (62.4%) treated their cat with anthelmintics 2-4 times per year.     

Increasing prevalence of Coxiella burnetii seropositive Danish dairy cattle herds

A study based on bulk tank milk samples from 120 randomly selected dairy cattle herds was conducted to estimate the prevalence of Coxiella burnetii seropositive dairy herds, to describe the geographical distribution, and to identify risk factors. Using the CHEKIT Q-fever Antibody ELISA Test Kit (IDEXX), the study revealed a prevalence of 79.2% seropositive herds, 18.3% seronegative herds, and 2.5% serointermediate herds based on the instructions provided by the manufacturer. Multifactorial logistic regression showed statistically significant associations (P < 0.01) between C. burnetii seropositivity and increasing herd size (OR = 1.02 per cow increment) and increasing regional average number of cattle per dairy herd (OR = 1.02 per animal increment). Herds >150 cows had 17.9 times higher odds of testing positive compared to herds <80 cows. The regional average number of cattle herds per square kilometer was borderline significantly related to the occurrence of seropositive dairy herds (P = 0.06). The results indicate an increased prevalence of seropositive dairy herds since the previous survey in 2008 and an adverse impact of increasing herd size and cattle density on the risk of seropositivity.     

Nation-wide Salmonella enterica surveillance and control in Danish slaughter swine herds

A nation-wide Salmonella enterica surveillance and control programme was initiated in Danish finishing herds over the first quarter of 1995. In Denmark, all swine for slaughter are identifiable by a unique herd code. For each herd code, and depending on the herd's annual kill, random samples ranging from four to more than 60 swine are obtained quarterly at the abattoir. A meat sample from each pig is frozen, and meat juice (harvested after thawing) is examined for specific antibodies against S. enterica using an indirect enzyme-linked immunosorbent assay (ELISA). The ELISA combines several S. enterica O-antigens, and allows detection of antibody response after a variety of different S. enterica serovar infections. Results are transferred to a central database, which each month (based on meat-juice tests obtained in the previous 13 weeks) assigns all herds into three S. enterica infection levels: Level 1, in which the S. enterica prevalence is deemed low and acceptable; Level 2, where there is a moderate prevalence of S. enterica seroreacl.ors (from > 50% in the smallest to > 10% in the largest herds); Level 3, in which S. enterica seroreactor prevalence is clearly unsatisfactory ( > 50% for most herd sizes). Irrespective of Salmonella level, all herds receive a monthly update on the current results of the S. enterica test results. If a herd is categorized in Level 2 or 3, it must receive an advisory visit by a practising veterinarian and a local swine extension specialist, and certain management hygiene precautions must be taken. If a herd is categorized in Level 3, the finishers from the herd must additionally be slaughtered under special hygiene precautions. This is supervised by the veterinary authorities.

During 1995, 604000 samples were tested for S. enterica, corresponding to 3.0% of the total kill. In December 1995, 15522 herds (representing > 90% of the national production) were categorized into one of the three levels: 14551 herds (93.7%) in Level 1; 610 herds (3.9%) in Level 2; 361 herds (2.3%) in Level 3. The proportion of serologically positive meat-juice samples collected during 1995 ranged from a mean of 2.9% in smaller herds (101–200 swine slaughtered per year) to 6.1% in relatively large herds (more than 5000 swine slaughtered per year).     

Loser cows in Danish dairy herds: definition, prevalence and consequences

During the last few years, many Danish dairy farmers have expressed increasing concerns regarding a group of cows, which we have chosen to term ‘loser cows’. Until now, a loser cow has not been described scientifically. We defined a loser cow on the basis of a clinical examination of the cow. A total of 15,151 clinical examinations were made on 6,451 individual cows from 39 randomly selected, large Danish dairy herds with loose-housing systems using a clinical protocol. Scores for the clinical signs lameness, body condition, hock lesions, other cutaneous lesions, vaginal discharge, condition of hair coat and general condition were converted into a loser cow score. Cows with a loser cow score of 8 or more were classified as loser cows. The overall prevalence of loser cows was 2.15%, 4.50% and 2.98% during the first, second and third round of herd visits, respectively.

The associations between the loser cow state and milk production, mortality, morbidity, culling and workload for the farmer were evaluated using data from herd visits and from the Danish Cattle Database and a number of different statistical techniques. It was concluded that the loser cow state has significant negative consequences for both the farmer and the cow. On average, loser cows yielded 0.61 to 2.24 kg energy corrected milk less per day than non-loser cows depending on parity. Hazard ratio for death or euthanasia was 5.69 for loser cows compared to non-loser cows. Incidence rate ratio for disease treatments was 0.69 for non-loser cows compared to loser cows. Loser cows were often culled in an ‘unfavourable’ way and generally caused extra workload for the farmer.

A simplified version of the loser cow score was evaluated and is recommended for future research and use in practice.     

Associations ofAscaris suum and Oesophagostomum spp. infections of sows with management factors in 83 Danish sow herds

Associations of the occurrence of Ascaris suum and Oesophagostomum spp. in sows with herd management factors were examined using logistic-binomial regression. The information used was from 11 to 78 sows sampled from each of 83 breeding herds (2961 sows in total) and examined for eggs per gram of faeces (EPG). A sow excreting at least 20 EPG was defined as ‘infected’. Management factors of the study herds were recorded using a questionnaire. A total of 263 sows from 50 herds (8.9% of sows) and 375 sows from 20 herds (12.7% of sows) were infected with A. suum and Oesophagostomum spp., respectively. For A. suum, sows from herds with more than 85 sows had significantly higher odds of being infected compared with those from 30 to 85 sows (P < 0.05). When bedding was provided for sows, the odds of A. suum infection was 5.4 compared with sows from herds in which bedding was not provided (P < 0.05). For Oesophagostomum spp., sows from herds with different specific pathogen free status had about one tenth the odds of being infected compared with those from conventional herds (P < 0.05). Sows that had been treated with anthelmintics had very low odds of being infected with Oesophagostomum spp. compared with those that were not treated (P < 0.05). The effects of these management factors in both final models did not differ when the definition of an ‘infected’ sow was changed. The present results suggest the importance of disposal of bedding material from pens in reducing the prevalence of A. suum in larger sow herds. Anthelmintic treatment is important in reducing the prevalence of Oesophagostomum spp. infection of sows.     

Epidemiological studies of piglet diarrhoea in intensively managed Danish sow herds. III. Rotavirus infection

The prevalence of rotavirus infection was studied in 1090 litters from 26 sow herds. Samples of normal, semifluid and watery stools were examined for rotavirus by an ELISA-test on faeces. Rotavirus was detected in 77% of the herds and in 30.5% of the litters (prevalence rates). The highest prevalence rate was seen in piglets between 21 and 41 days of age. Gilts' litters had a very high prevalence during the first week of life. Apart from this, no difference was found between litters from gilts and older sows. Rotavirus was detected more frequently in semiliquid, loose stools than in normal or watery stools, and an association between virus detection and diarrhoea could not be demonstrated. However, litters which shedded rotavirus during the suckling period had lower weight gains and higher incidence rates of respiratory diseases than virus-free litters. Litters weaned at 2 weeks in battery cages had slightly increased risk of shedding rotavirus compared to litters weaned in more traditional systems. The study revealed that rotavirus is widespread in Danish swine herds. The findings give evidence to suggest that the type of mild diarrhoea in 3-week-old piglets known as steatorrhoea or "white scours" may be associated with rotavirus infection, possibly in combination with E. coli and other agents. The high prevalence in piglets weaned at 2 weeks plus the higher morbidity and mortality among such piglets sustain the conclusion that piglets should not be weaned before 3 weeks of age or below a body weight of 6-7 kg.     

Epidemiological studies of piglet diarrhoea in intensively managed Danish sow herds. I. Pre-weaning diarrhoea

The study comprised 70,796 litters in 104 sow herds, observed from 1976 through 1982. Weaning age decreased from approx. 42 days to approx. 30 days during the observation period. Diseases and symptoms were recorded together with production parameters (feeding, barn construction, economic returns etc.). The mean incidence rate of pre-weaning diarrhoea was 6.8% of litters, with considerable inter-herd differences (incidence rates from 0 to approx. 50%). There was a slight increase in incidence during the autumn (August through October). Incidence rates increased with litter size, with a peak incidence in litters of 11-13 piglets, and decreased with increasing parity of the sow. There was a positive association between occurrence of arthritis and pre-weaning diarrhoea in the litters, and litters from sows with post parturient disease (MMA complex) had 1.8 times higher risk of getting diarrhoea than litters from healthy sows. No important differences among breeds were found. Small herds (less than 200 farrowings per year) had higher incidence rates than large herds (400-499 farrowings per year). Herds with a gilt proportion above 30% had an incidence rate of 12.3%, i.e. nearly twice as high as the overall mean (6.8%). There was a trend towards a higher incidence rate in litters kept in traditional pens (i.e. large pens with solid floor and loose sows) than in intensive pens (i.e. small pens with slatted flooring and tethered sows). The overall pre-weaning mortality rate was 16.2% of pigs born, half of which was due to stillbirths (6.3%) and overlaid piglets (2.2%). In litters with pre-weaning diarrhoea, the mortality rate was 19%, compared to 13% in litters without occurrence of diarrhoea. This difference accounts for an excess loss of 0.6 piglets from birth to weaning in diarrhoeic vs. non-diarrhoeic litters. Piglets from litters with pre-weaning diarrhoea had reduced weight gain. Thus, on the average, they were 2.2 days older at 25 kg bodyweight and weighed 0.4 kg less at 30 days than piglets from non-diarrhoeic litters. Also, litters with pre-weaning diarrhoea had a significantly increased risk of post-weaning diarrhoea. The present information forms a basis for defining acceptable disease thresholds in suckling litters in intensively managed herds.     

Epidemiological studies of piglet diarrhoea in intensively managed Danish sow herds. II. Post-weaning diarrhoea

This study comprised 48,931 litters in 89 sow herds. During the study (1976-82) weaning age decreased from approx. 42 days to approx. 30 days. The mean incidence of post-weaning diarrhoea was 6.0% of litters weaned, with little variation by year but with considerable variation among herds. Within the individual herd increased incidence occurred over limited periods, probably associated with specific infections. Litters with diarrhoea during the suckling period had increased risk of post-weaning diarrhoea. The incidence of post-weaning diarrhoea increased with litter size at weaning. Thus, a litter of 11-12 piglets at weaning had 1.2 times higher risk than litters with 8-10 piglets. In contrast to pre-weaning diarrhoea, there was no association between parity of the sow and diarrhoea in the litter after weaning. Litters weaned below 2 weeks of age had a 2-fold risk of developing diarrhoea after weaning and a 2.4-fold higher mortality rate than did litters weaned at 6-7 weeks. Similarly, litters weaned at an individual piglet weight below 3 kg bodyweight had a 3-fold higher risk of developing diarrhoea after weaning and a 5-fold higher mortality rate than did pigs from litters weaned at a bodyweight of 7-8 kg. The incidence of post-weaning diarrhoea decreased with increasing herd size. Piglets from litters with post-weaning diarrhoea had reduced weight gains after weaning and were 2.3 days older at 25 kg bodyweight than piglets from non-diarrhoeic litters. Likewise, diarrhoea after weaning was associated with an increased incidence of diseases of the skin and respiratory tract. Thus the risk of contracting respiratory disease was 4 times greater in diarrhoeic litters.     

Bulk-tank milk ELISA antibodies for estimating the prevalence of paratuberculosis in Danish dairy herds

Paratuberculosis (Johne's disease) has been widespread in Danish dairy herds for a long time but the herd-level prevalence has never been determined precisely. To evaluate the prevalence of paratuberculosis in Danish dairy herds in various regions, an ELISA based on a commercially available antigen was adapted for testing bulk-tank milk for the presence of antibodies to Mycobacterium avium subsp. paratuberculosis. Bulk-tank milk samples were collected from six milk-collecting centres from six different areas of the country. Samples from 900 herds (about 7.5% of all Danish dairy herds) were examined, and 70% were positive at the statistically optimal cut-off (sensitivity 97.1%; specificity 83.3%). The technical performance of the ELISA was not sufficient to provide a tool for surveillance because even slight changes in optical density for the samples would change the classification of some samples. The infection is more widespread than previous investigations have shown.     

Annual incidence, prevalence and transmission characteristics of Streptococcus agalactiae in Danish dairy herds

Contagious mastitis pathogens continue to pose an economic threat to the dairy industry. An understanding of their frequency and transmission dynamics is central to evaluating the effectiveness of control programmes. The objectives of this study were twofold: (1) to estimate the annual herd-level incidence rates and apparent prevalences of Streptococcus agalactiae (S. agalactiae) in the population of Danish dairy cattle herds over a 10-year period from 2000 to 2009 inclusive and (2) to estimate the herd-level entry and exit rates (demographic parameters), the transmission parameter, β, and recovery rate for S. agalactiae infection. Data covering the specified period, on bacteriological culture of all bulk tank milk samples collected annually as part of the mandatory Danish S. agalactiae surveillance scheme, were extracted from the Danish Cattle Database and subsequently analysed. There was an increasing trend in both the incidence and prevalence of S. agalactiae over the study period. Per 100 herd-years the value of β was 54.1 (95% confidence interval [CI] 46.0-63.7); entry rate 0.3 (95% CI 0.2-0.4); infection-related exit rate 7.1 (95% CI 5.6-8.9); non-infection related exit rate 9.2 (95% CI 7.4-11.5) and recovery rate 40.0 (95% CI 36.8-43.5). This study demonstrates a need to tighten the current controls against S. agalactiae in order to lower its incidence.     

High prevalence of bovine viral diarrhea virus 1 in Chinese swine herds

Nested RT-PCR was used to investigate bovine viral diarrhea virus in 511 specimens collected from Chinese pigs exhibiting clinical symptoms between 2007 and 2010. Of these, 137 samples were BVDV-positive and the BVDV prevalence rate was 23.1% (9/39) in 2007, 27.7% (44/159) in 2008, 33.6% (34/101) in 2009, and 23.6% (50/212) in 2010. Twenty of 137 BVDV-positive samples were used for further genetic analysis of the 5'-UTR. Phylogenetic analysis revealed that they were BVDV-1 and subtyped into BVDV-1a, BVDV-1b, BVDV-1m, BVDV-1o and an unknown subgenotype. This study showed that BVDVs were highly prevalent in Chinese pig herds and appropriate measures should be taken to control BVDV prevalence in pig herds.