Effect of medium- and long-chain triglyceride supplementation on small newborn-pig survival

The pre-weaning survival of 508 piglets was studied with a categorical survival analysis, evaluating the effect of medium-long-chain triglyceride (MCT-LCT) supplementation on small newborn pigs, and determining additional risk factors. Half of the 98 piglets born with birth weight (BW)<1250 g received 1.95 g of MCT-LCT each 24 h during the first 3 days of life, and their death hazard was reduced 1.9-fold in relation with small unsupplemented siblings. The death hazard ratio (HR) of supplemented animals compared to 410 heavier littermates was not different. However, the HR for newborn pigs that were small in relation with their siblings was 2.8, and the HR for litters with >12 piglets born alive was 4.5. There was variation across months, and also piglets from primiparous sows had increased hazard of death (HR=4.0).

Field evaluation of the effect of a probiotic-containing Bacillus licheniformis and Bacillus subtilis spores on the health status, performance, and carcass quality of grower and finisher pigs

The aim of the study was to assess the efficacy of BioPlus 2B, a probiotic containing Bacillus licheniformis and B. subtilis spores, on the health status and productivity of pigs, during weaning, growing and finishing stages of growth. On a commercial farrow‐to‐finish farm, five experimental groups were formed, each of 54 weaned piglets. The pigs of the first group (double controls) received normal feed with no probiotic and the pigs of the second group (untreated controls) received BioPlus 2B only during the weaning stage. The pigs of the third, the fourth and the fifth group received the same as the second group feed but, at the growing and at a part of the finishing stages, supplemented with three different doses of Bioplus 2B, a low, medium and high dose, respectively. The results have shown that, compared with the double controls, BioPlus 2B‐treated pigs had a lower morbidity and mortality during the whole trial period, compared with the double controls (range from 9.26 to 14.81% versus 25.93% and from 0.00 to 3.70% versus 11.1%, respectively), as a result of the lower incidence of post‐weaning diarrhoea due mainly to Escherichia coli. Weight gain, feed conversion ratio and carcass quality of the BioPlus 2B‐treated pigs were significantly improved compared with the double controls, whilst the beneficial effects of the probiotic were more pronounced when the medium and high doses were used.

Reduction of economic losses caused by mycoplasmal pneumonia of pigs by vaccination with Respisure and by Tiamutin treatment

The possibilities and economic benefits of controlling mycoplasmal pneumonia of pigs caused by Mycoplasma hyopneumoniae by immunisation with Respisure and by Tiamutin treatment were studied. The experiment was carried out in a herd comprising 1000 sows which was free of PRRS, Aujeszky's disease, swine dysentery and leptospirosis, and the prevalence of mycoplasmal pneumonia was low because the farm had recently been restocked. Groups C1 and C2 served as untreated controls, while Groups R1 and R2 received a prestarter diet containing 100 ppm Tiamutin from the time of weaning. Piglets of Group R1 were vaccinated with Respisure vaccine once on day 69, while those of Group R2 twice, on days 65 and 80. Piglets of Groups ST1 and ST2 were fed 100 ppm Tiamutin in the diet for 7 days at the time of weaning and then at 4 months of age, while pigs of Group ST2 received such treatment also in the 6th month of life. The efficacy of treatment was analysed on the basis of the number of animals that died, were emergency slaughtered or were retarded in growth in the different groups, the body weight of animals at weaning, at 94 and 148 days of age and at the time of slaughter, their daily body weight gain, the lung lesions found in animals slaughtered from the different groups, the costs of medication and vaccination, and the cost-benefit calculations of the results. The mortality and emergency slaughter rate was 2.88% and 4.62% in Groups ST2 and ST1, respectively, 4.23% and 4.62% in Groups R2 and R1, respectively, and 8.39% and 9.44% in the control groups (C2 and C1, respectively). The rate of growth retardation was 0.48% and 2.12% in Groups R1 and R2, respectively, 1.59% and 3.46% in Groups ST1 and ST2, respectively, as compared to 8.03% and 6.55% in the control groups (C1 and C2, respectively). The severity score of lung lesions was 1.82 and 1.46 in Groups R1 and R2, 2.18 and 2.93 in Groups ST1 and ST2, and 3.83 and 4.02 in the control groups C1 and C2, respectively. The mean finishing weight of pigs was 102.4-107.8 kg and 95.2-106.6 kg in the treated groups and 94.5-98.6 kg in the control groups. The classification of pigs according to the EUROP categories showed a shift to the E and U categories in the treated groups. The average feed cost per one kg of liveweight was 77.89-82.64 Forints in the treated groups and 85.66 Forints in the control groups.

A study of the progress of the Aujeszky's disease control programme in Italy using survival analysis

A 3-year study (1997-2000) was performed on 294 swine herds from Italy, where a National Programme of Control of Aujeszky's Disease (AD) based on compulsory vaccination has been operative since 1997. Aim of the study was to evaluate the progress of this control programme using a survival approach applied to gE-seropositive herds at the beginning of the programme. The cumulative proportion of herds still gE-seropositive at the end of the study was 0.57. No significant difference in the probability of becoming gE-seronegative during the study period was found between herds of different type (breeding versus farrow-to-finish) whereas significant differences were seen between herds from different areas. The Cox's proportional hazards regression, performed on data from 79 herds, showed that the only risk factor significantly associated with a higher probability of becoming gE-seronegative is again the geographical location. Other risk factors considered in the analysis were: type of enterprise, type of replacement of animals, herd size, pig and pig herds densities around the farm, distance from the nearest pig herd and year of beginning of the vaccination with a gE-deleted vaccine.

A prolonged outbreak of polioencephalomyelitis due to infection with a group I porcine enterovirus

A commercial swineherd in Indiana experienced high death loss of nursery pigs with neurologic disorders for a prolonged period. Polioencephalomyelitis was the consistent histopathological lesion in affected animals. A porcine enterovirus (PEV) classified to group I was isolated from spinal cords and brains collected from the affected animals. The isolate (ISUVDL 200103183) was determined to belong to either serogroup 5 or 6 at the National Veterinary Services Laboratories, Ames, IA. No other significant viral or bacterial agents were isolated from or detected in the animals. A prospective longitudinal serological monitoring of pigs in the index herd for the PEV isolate revealed that colostrum-derived neutralizing antibodies to the virus rapidly declined, and by the age of 21 days the majority of piglets had no or minimal neutralizing antibody against the virus. Seroconversion to the virus then coincided with increased mortality in the herd. Results of diagnostic and cohort observations supported a diagnosis of PEV infection as the cause of the prolonged outbreak of "polio." Investigation into factors that may be contributing to the prolonged problem is currently in progress.

Uptake of colostral immunoglobulins by the compromised newborn farm animal

Neonatal mortality is very high in farm animals (approximately 10%) and disease resistance is greatly influenced by an adequate passive immunisation just after birth. In piglets, foals, calves and lambs, the intestinal absorption of immunoglobulins from their mother's colostrum occurs mainly by a non-specific endocytosis of macromolecules, but the details of the absorption process, and the mechanisms regulating its cessation after 1-2 days of colostrum exposure, remain poorly understood. In both normal and 'compromised' (premature, growth-retarded, hypoxic, lethargic) newborn farm animals, the intestinal capacity to absorb macromolecules is influenced by both diet- and animal-related factors. Thus, macromolecule uptake is severely reduced in response to premature birth and when macromolecules are to be absorbed from diets other than species-specific colostrum. On the other hand, fetal growth retardation, in vitro embryo production, or a stressful birth process are unlikely to reduce the ability of the intestine to absorb immunoglobulins from colostrum. More knowledge about the diet- and animal-related factors affecting intestinal immunoglobulin uptake will improve the clinical care of 'compromised' newborn farm animals. The present text gives a brief introduction to the process of intestinal immunoglobulin absorption in large farm animals and describe some recent results from the author's own studies in pigs, calves and lambs.

Natural Aujeszky's disease in a Spanish wild boar population

We describe an outbreak of Aujeszky's disease (AD) in a wild boar (Sus scrofa) population from central Spain. Mortality was estimated to be at least 14% (14/100) in juveniles and 7.5% (3/40) in adults. Most of the affected animals (12/17) were between 4 and 8 months of age. Gross lesions mainly consisted of enlarged and congestive tonsils and lymph nodes, petechial hemorrhages on the small intestine, and engorged blood vessels in the brain and meninges. Histopathology revealed mild nonsuppurative meningoencephalitis. Positivity to the fluorescent antibody test was found in tissues from the affected animals. Seroprevalence of antibodies to AD virus (ADV) was 56% (9/16). To our knowledge, this is the first description of clinical cases in a wild suid population.

Iron deficiency in outdoor pig production

It has been claimed that outdoor-reared suckling piglets do not need iron supplementation. According to practical experience, outdoor-reared and non-iron-supplemented piglets show a lower performance in comparison with their iron-supplemented counterparts. The purpose of the present study was to determine the effect of iron supplementation on outdoor-reared suckling piglets. In a large Hungarian outdoor pig production unit, 4691 piglets were assigned to one of two treatment groups. Piglets in group 1 (n = 2344): received no iron supplementation, whereas piglets in group 2 (n = 2347) were intramuscularly injected in the neck on day 3 post-partum with 1.5 ml of Ferriphor 10% solution (TAD Pharmaceutical GmbH, Bremerhaven, Germany). Animal weights, morbidity, haemoglobin concentration and mortality were recorded and analysed. At weaning the iron-injected piglets were significantly (P < 0.05) heavier. The iron-supplemented piglets also revealed significantly (P < 0.01) less pre-weaning morbidity and mortality and higher (P < 0.01) blood haemoglobin concentration compared with the non-injected ones. This study suggests that in order to prevent pre-weaning losses and support piglet health and weight performance, iron supplementation should be administered to piglets in outdoor pig production units.

Causes of sow mortality in Hungarian indoor and outdoor pig production units

Assessing the reasons for death in pig breeding units is the first step in understanding and controlling the factors influencing sow losses due to mortality. From October 1997 to October 2001 in forty-nine indoor (2876 sows died) and sixty-five outdoor breeding units (3451 sows died) sow mortality was evaluated. The average annual mortality rate during the four year evaluation period was 5.1 +/- 1.2% in indoor and 12.2 +/- 2.1% in outdoor production units. Swine urogenital disease (SUGD, 32.4%), heart failure (HF, 21.8%) and locomotor problems (LP, 33.1%) caused deaths were markedly higher in outdoor production, while periparturient diseases (mastitis-metritis-agalactia, MMA, 24.5%) and torsion or distension abdominal organs (TDA, 20.5%) revealed markedly higher losses in indoor units. The annual culling rate was 39.1% in the indoor and 45.2% in the outdoor units. In outdoor units 40.1% of all deaths occurred during the periparturient period of the reproductive cycle, in indoor units the majority of mortality happened during lactation (40.2%). Average parity at death was 3.6 in indoor and 2.5 in outdoor production.

[Culling of animals in large herds, experiences from the Netherlands]

The outbreaks of classical swine fever in 1997-1998 and foot- and mouth-disease in 2001 provided a lot of experiences in the culling of animals. These experiences, as well as the aspects of animal welfare and public acceptance are described. In the future these experiences will help to carry out culling in a more efficient way including improved aspects of animal welfare and public acceptance.

Mortality associated with gastric ulceration in swine

On a large swine operation, necropsy revealed that 39 of 146 (27%) pigs during one week in April and 37 of 137 (27%) pigs during one week in June died from hemorrhage due to gastric ulceration. Contributory factors may have been feed withdrawal one day per week and feeding finely ground pellets.

Emergency-culling and mortality in growing/fattening pigs in a large Hungarian "farrow-to-finish" production unit

The trial was carried out in a large Hungarian 2000 sow "farrow-to-finish" production unit. Out of a total number of 15,841 evaluated growing/finishing pigs, 1319 pigs died or were emergency-culled and were post-mortem routinely examined. For the purpose of this study the emergency-culling and mortality were recorded into the same category. The average annual emergency-culling/mortality rate was unusual high (8.62%). Five body condition related categories were registered. The majority of the mortality comprised animals of body condition "below average", representing 891 pigs (67.56%) and "average" (407 pigs = 30.85%). The rest of the examined animals comprised 17 pigs (1.29%) "emitted", 2 pigs "kachexia" (stunted pig) or "fat" (0.15% each). The overall study showed that gastrointestinal tract disorders (395 animals = 29.95%) were the most frequently recorded cause of emergency-culling or mortality. Both inflammatory disorders (7.66%) and rectal stricture (7.51%) were in this category the most frequent diagnosis followed by rectal prolapse (5.92%). Gastric ulcers comprised 4.55% of the necropsied animals. Torsion of abdominal organs and miscellaneous cases represented slightly more than 2% of the post-mortem examined pigs. Lesions which involved the respiratory system, comprised 14.85% of the necropsied pigs. Bronchopneumonia due to Mycoplasma hyopneumoniae occurred in 5.61%, embolic suppurative or necrotic pneumonia in 4.78% and pleuropneumonia due to Actinobacillus pleuropneumoniae in 3.1% of the cases. Diseases involving the urinary system were diagnosed in 21 cases (1.59%). Five cases of skin disorders were registered (0.38%). Cardiovascular disorders were represented by congestive heart failure (31 pigs = 2.35%), pericarditis (22 animals = 1.66%) or endocarditis (21 pigs = 1.60%). Cardiomyopathy was found in 15 (1.2%) animals. Lesions involved the locomotor system ranked second of all cases (15.92%). Claw lesions accounted 13.72%, arthritis 2.13% of the animals and luxation or fracture was diagnosed only in one case (0.07%). Systemic infections were reported in 96 cases (7.28%) including polyserositis (4.09%), erysipelas, edema disease or miscellaneous causes (each category slightly more than 1%). Genetic problems were involved in 8.19% of the fatal cases and social stress or cannibalism related culling or mortality comprised 37 animals (2.81%). In 161 cases (12.20%) of the mortality the causes of death were not established. Two or more lesions related to culling or mortality were found in 320 pigs (24.26%, p < 0.001). The most common diagnosed pathologic changes in association with other lesions were Mycoplasma hyopneumoniae caused bronchopneumonia (4.09%), embolic suppurative or necrotic pneumonia (4.55%), followed by inflammatory gastrointestinal problems (3.10%), gastric ulcer (2.35%), claw lesions (2.19%) and arthritis (1.14%). It appears from the presented study that a routine post-mortem examination of all emergency-culled or dead pigs over a long period of time gives a clear picture of causes of mortality enabling the management to plan management strategies as vaccination programs, genetic improvements and optimising environmental conditions.

The effects of immuno-modulation on the clinical and pathological expression of postweaning multisystemic wasting syndrome

Post-weaning multisystemic wasting syndrome (PMWS), primarily caused by porcine circovirus type 2 (PCV-2), is an economically important disease of pigs in many countries. A trial was designed to investigate the hypothesis that non-specific immuno-modulation can influence the clinical and pathological expression of PMWS in pigs naturally infected with PCV-2. Eighty-four pigs on a commercial pig farm were allocated to three groups of 28 pigs each, during an outbreak of PMWS. The pigs in the first group received an intramuscular injection of a vaccine against Mycoplasma hyopneumoniae (RespiSure, Pfizer, NY, USA) at each of 7 and 28 days of age, followed by an intramuscular injection of normal saline at 42 days of age. The animals in the second group received, by intramuscular injection, normal saline at 7 days of age followed by a non-specific immuno-modulating drug (Baypamun, Bayer, Leverkusen, Germany) at each of 28 and 42 days of age. The pigs in the third (control) group received an intramuscular injection of normal saline on each of 7, 28 and 42 days of age. The trial was concluded when the pigs had reached the age of 73 days. Clinical signs characteristic of PMWS developed in 42.9% of pigs inoculated with RespiSure and in 50% of pigs treated with Baypamun; six pigs from each of these groups died. Moderate to severe gross and histopathological lesions of PMWS, associated with abundant PCV-2 antigen, were seen in a wide range of tissues of pigs from these groups at the end of the trial. In contrast, only 10.7% of pigs in the control group developed clinical signs and only one died. Mild to moderate lesions and scant PCV-2 antigen were occasionally observed in tissues of control pigs at the end of the trial. This is the first study to demonstrate that non-specific stimulation of the immune system by a vaccine or an immuno-modulator drug can potentiate viral replication and increase the severity of clinical signs during an outbreak of PMWS.

Effects of biphasic vs monophasic defibrillation on the scaling exponent in a swine model of prolonged ventricular fibrillation

OBJECTIVE

Mathematical analyses of ventricular fibrillation (VF) have resulted in the derivation of a measure termed the scaling exponent (ScE) that characterizes the duration of VF and probability of defibrillation success. The purpose of this study was to compare the effects of biphasic defibrillation waveform (BDW) and monophasic defibrillation waveform (MDW) rescue shocks on ScE in a swine model of prolonged VF.

METHODS

Utstein guidelines for the laboratory study of cardiopulmonary resuscitation were followed. Twenty mixed-breed domestic swine (mass range 20.5-26.8 kg) were instrumented and randomized to receive either MDW or BDW rescue shocks. Ventricular fibrillation was induced and untreated for a nonintervention interval of 8 minutes. Rescue shocks were delivered at 8, 10, and 12 minutes of elapsed VF time. The energy sequence for the three MDW shocks was 70, 100, and 150 J (approximately 3, 4, and 6 J/kg). All BDW shocks were delivered at 50 J (approximately 2.5 J/kg). Only VF was shocked. Chest compressions and drugs were not provided. Rhythm analysis and ScE calculation were performed offline. Continuous and discontinuous linear regression models were fit to plots of ScE vs time. Defibrillation success and progression of ScE slope were analyzed using Fisher's exact test, paired t-tests, and repeated-measures analysis of variance (ANOVA).

RESULTS

Baseline characteristics were similar for both groups. Successful termination of VF occurred on the first rescue shock in 1 of 10 (10%) in the MDW group and 3 of 10 (30%) in the BDW group; this difference was not statistically significant (p = 0.58). No other defibrillation successes were observed. No animals achieved return of spontaneous circulation. The ScE values during the protocol progressed from 1.330 (95% CI = 1.287 to 1.373) to 1.724 (95% CI = 1.603 to 1.845) for MDW and 1.338 (95% CI = 1.261 to 1.415) to 1.639 (95% CI = 1.530 to 1.745) for BDW. Both groups showed a trend toward increasing ScE values with successive rescue shocks. Repeated-measures ANOVA using both continuous and discontinuous models demonstrated no difference in overall ScE slope progression between study groups.

CONCLUSIONS

Mode of defibrillation waveform (BDW vs MDW) does not appear to impact ScE trends. Additional studies must be performed to better evaluate the clinical implications of this finding.

[Acute poisoning of pigs with hydrogen sulfide as a result of acidification of slurry on a pig farm]

On a fattening pig farm all 582 animals died of peracute intoxication with hydrogen sulphide (H2S). The accident took place after 6000 litres of lactic acid (41.5 mass %) was dumped in the slurry pit. The volume of released gas was about 575 m3. This resulted in sudden spreading by high pressure of a lethal concentration of hydrogen sulphide to all compartments of the pig house. Analysis of the situation indicated that the level of hydrogen sulphide was 7870 ppm.

Evaluation of the zootechnical parameters of vaccinating against swine enzootic pneumonia under field conditions

A field test was carried out in different production systems to evaluate the effect of vaccination against swine enzootic pneumonia with an inactivated vaccine. A total of 13,691 pigs of four different genetic origins were used, of which 7,351 were vaccinated and 6,340 were used as controls. The animals were housed in 16 fattening units, in which the 'one-site', 'two-site' and 'three-site' production systems were represented. There were the following statistically significant differences in favour of the vaccinated animals: a 1.89 per cent lower mortality (P<0.001), a 0.09 lower feed conversion ratio (P<0.030), a 3.12 per cent lower cost per kilogram gained in fattening (P<0.031), a 4.02 per cent lower cost per kilogram of carcase (P<0.018), a 3.77 per cent lower cost of feed per kilogram gained in fattening (P<0.012) and a 56.75 per cent lower potential loss of profit per kilogram gained in fattening due to mortality (P<0.001). An analysis of variance of the effects of genetic origin, treatment and production system on the different parameters showed that only the treatment had any statistically significant effect on the percentage mortality (P<0.002), feed conversion ratio (P<0.030), cost per kilogram gained in fattening (P<0.019), cost per kilogram of carcase (P<0.020), cost of feed per kilogram gained in fattening (P<0.015) and potential loss of profit per kilogram gained in fattening due to mortality (P<0.002).

Competitive exclusion treatment reduces the mortality and fecal shedding associated with enterotoxigenic Escherichia coli infection in nursery-raised neonatal pigs

We have previously reported that the administration of a competitive exclusion culture (PCF-1), derived from the cecal microflora of a young, healthy pig and maintained in a continuous flow fermentation system to neonatal pigs resulted in a decrease in the incidence of fecal shedding and cecal colonization by Salmonella choleraesuis in pigs at weaning. In the present experiment, we describe the effects of the administration of a derivative of the PCF-1 culture, RPCF, against an enterotoxigenic E. coli infection in neonatal pigs raised off-sow. The administration of RPCF at 12 and 24 hours after birth resulted in significant (P < 0.05) reductions in mortality, incidence of fecal shedding, and in gut colonization by E. coli when compared to control values. The RPCF reduced mortality from 17.5%, observed in untreated pigs, to 4.4% in RPCF-treated pigs. Fecal shedding of E. coli was reduced significantly (P < 0.05) in RPCF-treated pigs between Days 1 and 3 post-challenge. These results indicate that the RPCF culture is effective against one of the most important causes of neonatal scours (E. coli infections) in piglets.

Early identification of neonates at risk: traits of newborn piglets with respect to survival

Despite technological changes and improved management, piglet mortality remains a problem for both production and welfare. Most preweaning mortality occurs within the first 3 days after birth because of problems with adaptation and development. Thus, the purpose of our study was to determine the physiologic state of newborn pigs with respect to piglet survival. Data were collected from 1024 live-born piglets of 106 primiparous German Landrace sows to analyze relationships between farrowing traits, early postnatal vitality and blood chemistry, including immunity of piglets at birth. Surviving piglets were compared with those that died during the first 10 days of life. The survivors were significantly heavier at birth (P=0.001), were born earlier in the birth order (P=0.04), reached the udder and took in first colostral milk more quickly (P=0.001) and had a smaller drop in rectal temperature I h after birth (P=0.001) than dead. However, dead piglets had significantly higher blood levels of inorganic phosphorus (P=0.0001), calcium (P=0.04) and urea (P=0.05), but a lower concentration of alpha2-macroglobulin and lower lymphocyte proliferation indices in response to pokeweed mitogen (P=0.05). Models fitted for discrimination between survivors and piglets that died included, in addition to birth weight and litter size, the foraging behavior of neonates (time from birth to first suckle) and their thermoregulatory capacity (rectal temperature 1 h after birth) in the first experimental unit, as well as prenursing biochemical measures (inorganic phosphorus, calcium and glucose) in the second experimental unit. These ethophysiological and biochemical traits of early postnatal vitality are important determinants of maturity and development at birth. Hence, breeding programs and perinatal housing and feeding conditions should ensure a high physiological maturity to improve mortality rates of neonates.

[Effect of the Stellamune Mycoplasma vaccine on growth, energy conversion, death, and medication use in fattening pigs on a pig farm chronically infected with Mycoplasma hyopneumoniae]

The effect of Stellamune Mycoplasma vaccine, administered to piglets aged 2-15 days and then 13-15 days later, on daily weight gain, energy conversion, and use of medication was examined in fattening pigs on a chronically Mycoplasma hyopneumoniae infected pig farm. Half of the piglets were vaccinated and the other half acted as controls. In the study design, half of the pens in the fattening unit were allocated to vaccinated pigs; the other half to non-vaccinated pigs, pen was the experimental unit. In the fattening pens sows and castrated boars were separated. The study consisted of a total of 37 pens with vaccinated, and 37 pens with non-vaccinated pigs in 12 different compartments within the pig herd. In the finishing period, mean growth performance and mean energy conversion (EV/kg) of vaccinated animals was 65 grams/day higher and 0.07 EV/kg lower than in control pigs. Furthermore, the incidence of individual curative medication against respiratory problems was more than 4 times higher in control pigs than in vaccinated pigs. There was a tendency for a higher number of group medications against respiratory problems in control pigs than in vaccinated pigs. It is concluded that, in this herd, vaccination against M. hyopneumoniae was successful from an economic point of view.

Isolation and characterization of a capsule-deficient mutant of Actinobacillus pleuropneumoniae serotype 1

The capsular polysaccharides (CPS) play a major role in pathogenicity of Actinobacillus pleuroIpneumoniae, the causative agent of porcine pleuropneumonia. The purpose of the present study was to isolate a mutant in CPS biosynthesis by using a mini-Tn 10 transposon mutagenesis system and evaluate its adherence to host cells. One mutant apparently did not possess CPS as it did not react with a monoclonal antibody against A. pleuropneumoniae serotype 1 capsular antigen. Absence of capsule was confirmed by flow cytometry and also by transmission electron microscopy after polycationic ferritin labelling. The site of insertion of the mini-Tn 10 was determined and found to be in the cpxC gene. Its gene product, CpxC, is a protein involved in polysaccharide transport across the cytoplasmic membrane during CPS biosynthesis. Use of piglet tracheal frozen sections indicated that the CPS mutant adhered significantly (P=0.0001) more than the parent strain. The non-capsular mutant was less virulent in pigs compared to the parent strain and showed no mortality in experimentally infected pigs. The CPS mutant was however resistant to pig serum. This CPS mutant is the first A. pleuropneumoniae mutant in a CPS transport gene. It is also the first time that adherence of a CPS mutant of A. pleuropneumoniae is evaluated. Our observations indicate that capsular polysaccharides of A. pleuropneumoniae serotype 1 are not involved in adherence to piglet tracheal frozen sections but rather mask, at least in part, the adhesive functions.

Selenium elimination in pigs after an outbreak of selenium toxicosis

In May 1996, 150 grower pigs in 5 California counties were exposed to selenium-contaminated feed distributed by a single feed company. Feed samples from 20 herds had a mean selenium concentration of 121.7 ppm dry weight (range, 22.1-531 ppm). In San Luis Obispo County, 52 pigs in 24 herds were exposed to the feed, and 8 pigs died with signs of paralysis. Bilateral symmetrical poliomyelomalacia involving the ventral horns of the cervical and lumbar intumescence was evident on histologic examination of spinal cord from affected pigs. Of 44 surviving exposed pigs, 33 (75%) exhibited signs of selenosis, including anorexia, alopecia, and hoof lesions. Thirty-nine of 44 pigs (88.6%) had elevated (>1 ppm) blood selenium concentrations. Surviving exposed pigs were changed to a standard commercial ration containing approximately 0.5 ppm (dry weight) selenium. Blood selenium concentrations were determined weekly for 46 days following removal of the contaminated feed and were compared with values of 20 control pigs fed a standard commercial ration. Mean (+/-SD) blood selenium concentrations of exposed pigs were 3.2 +/- 2.6 ppm at the initial sampling and 0.4 +/- 0.1 ppm after 46 days. Mean blood selenium concentrations of < or = 0.3 ppm for control pigs at all samplings were significantly lower (P < 0.001) than concentrations for exposed pigs. Muscle and liver samples of 22 of the 44 exposed pigs were collected at slaughter approximately 72 days after withdrawal of the selenium-contaminated feed. Muscle samples had a mean selenium concentration of 0.36 ppm (wet weight). Liver samples had a mean selenium concentration of 1.26 ppm (wet weight). One liver sample had a selenium value in the toxic range for pigs (3.3 ppm wet weight; reference range, 0.4-1.2 ppm). A 1-compartment pharmacokinetic model of selenium elimination in exposed pigs was generated, and the geometric mean blood selenium elimination half-life was estimated to be 12 days. The 60-day withdrawal time recommended by the Food Animal Residue Avoidance Database was considered sufficient to allow safe human consumption of tissues from exposed pigs.

Mortality attributed to respiratory problems among finisher pigs in the United States

In the 1995 National Swine Study of the United States National Animal Health Monitoring System, producers identified respiratory problems as the leading cause of death in pigs during the grower/finisher phase of production. Over a six-month period, 61.7 +/- 4.1% (mean +/- SEM) of operations reported at least one death attributed to respiratory problems among finisher pigs (based on 388 operations representing operations with > or = 300 finisher pigs in 16 states). Mean mortality attributed to respiratory problems was 0.9 +/- 0.1% of finisher pigs per operation. Stepwise logistic regression (using SAS) was used to identify factors associated with operations attributing at least one death to respiratory problems, and to identify factors associated with reporting > or = 2% mortality attributed to respiratory problems. Final models were run with SUDAAN to account for the sampling strategy. Attributing at least one death to respiratory problems was associated with having > or = 3000 pigs enter the grower/finisher unit over a six-month period; diagnosis of Haemophilus (or Actinobacillus) in the past 12 months; and keeping pigs in the grower/finisher unit > 120 days (as compared to < 100 days). Not having a farrowing facility, mean weaning age < 28 days, and < 50% of finisher pigs on solid concrete only were associated with reporting > or = 2% mortality attributed to respiratory problems.

Dual infection with enterotoxigenic Escherichia coli and porcine reproductive and respiratory syndrome virus observed in weaning pigs that died suddenly

Diarrhea, sudden death after short duration of diarrhea and sudden death without apparent signs were observed in a herd of breeder pigs. Five pigs that died suddenly with diarrhea (SDD pigs) and 6 pigs that died suddenly without signs (SD pigs) were examined. The average age of the pigs was about 28 days. Twelve pigs of age 10 to 14 days old showing diarrhea (D pigs) were also examined. Eleven of them recovered. Large numbers of Escherichia coli were detected in all organs of every SDD and SD pig and in feces of D pigs. All of the isolates were identified as enterotoxigenic E. coli (ETEC) by the polymerase chain reaction (PCR). Porcine reproductive and respiratory syndrome (PRRS) virus cDNA was also detected from the lung of every SD and SDD pig by the RT-PCR. High and low titers of antibodies to PRRS virus were found in 10-day-old and 1-month-old pigs, respectively. In an experiment, 3 ETEC were isolated from 9 healthy weaning pigs during the quiescent stage in the herd. These data showed that growth of the ETEC was not active in healthy weaning pigs; however, following infection with PRRS virus ETEC infection became systemic and caused peracute death in the weaning pigs. It suggested also that infection with PRRS virus in 10-day-old pigs were protected by the colostral antibodies, and fatal infection by ETEC did not occur as a result.

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.

Virulence of Streptococcus suis type 2 for mice and pigs appeared host-specific

A murine model for Streptococcus suis infection in pigs was validated by inoculating groups of 5 BALB/c and 5 CF1 mice with 10(7) CFU/ml of 13 different S. suis serotype 2 strains. The pathogenicity of these strains had been established in a standardized pig model of S. suis infection using one-week-old gnotobiotic pigs. We inoculated groups of mice intraperitoneally with 4 strains that were highly virulent for pigs and belonged to the phenotype MRP+EF+, with 4 strains, that were weakly virulent for pigs and belonged to the phenotype MRP+EF+, and with 5 strains that were non-virulent for pigs and belonged to phenotype MRP-EF-. The S. suis strains that were highly virulent for pigs caused high morbidity and an intermediate mortality in mice, the S. suis strains that were weakly virulent for pigs caused high morbidity but low mortality, and the strains that were non-virulent for pigs, induced highest morbidity and mortality. These results were comparable in both breeds of mice. In contrast to the pathology of S. suis infection in pigs with specific lesions, lesions in mice were histologically often characterized as non-specific, i.e., necrotizing encephalitis and focal or diffuse hepatitis sometimes with abscesses. Irrespective of breed (BALB/c vs. CF1), the murine model used for S. suis infection was incompatible with the pig model. This indicates that virulence of S. suis type 2 for mice and pigs is host-specific. Therefore, we regard the presently available murine models unsuitable for studying S. suis infections in pigs.

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 0.75 kg and it was often correct. To pigs with a weight at death over 1.75 kg, they rarely gave 'a diagnosis other than unknown', but when they did it was often correct.

Comparison of the pathogenic, antigenic and molecular characteristics of two encephalomyocarditis virus (EMCV) isolates from Belgium and Greece

The pathogenicity of two porcine encephalomyocarditis virus (EMCV) isolates for sows in gestation and young piglets was studied. One virus originated from a case of reproductive failure in pigs in Belgium and the other from a case of acute myocarditis in pigs in Greece. Sows in the mid-gestation period and one- to two-month old piglets were inoculated with each isolate. The molecular relationship between both isolates was studied by determining the nucleotide sequence located across the junction of the 1C and 1D capsid-coding genes. Antigenic analysis was performed using a panel of 35 monoclonal antibodies raised against an Italian field isolate of EMCV. All three approaches revealed differences between both isolates and also confirmed that there was no link between the two outbreaks of disease.

Anaemia and low viability in piglets infected with Eperythrozoon suis

Eperythrozoon suis infection was identified in a pig herd during an investigation into anaemia and low viability in newborn piglets and severe regenerative macrocytic anaemia in older piglets. The organisms were identified in the erythrocytes of piglets a few days old. Extensive investigations failed to detect other causes of the anaemia and low viability. There was no response to parenteral iron administration alone but the piglets' viability and anaemia responded to the administration of tetracyclines. This is the first report of E suis infection in Northern Ireland.

Epidemiological characteristics of an outbreak of classical swine fever in an area of high pig density

The objective of this study was to analyse an outbreak of classical swine fever under a policy of non-vaccination, intensive surveillance and eradication in an area of high pig density. The virus was found in 52 herds, where some 90,000 pigs were slaughtered. The clinical signs were vague and the reports of suspect herds generally coincided with increased mortality. The interval between the first occurrence of clinical signs and the report of a suspect herd was shorter when the disease was first diagnosed in fattening pigs than when it was diagnosed in sows, boars or suckling piglets. Among fattening pigs, mortality and morbidity appeared to increase with age. The proportion of clinically ill animals was positively correlated with the proportion of serologically positive animals in a pig house during the phase when the disease was spreading. Fifty-eight per cent of pig houses containing only clinically healthy but some virologically positive pigs were serologically negative. Antigen detection was therefore critical for early disease detection. Serology was nevertheless useful to ascertain that swine fever was not endemic in the area. The secondary cases were concentrated in the close neighbourhood of the herd initially infected.

Effect of salinomycin in the control of Clostridium perfringens type C infections in sucklings pigs

The ability of salinomycin to control Clostridium perfringens type C infection in sows and their offspring was examined under field conditions. Two groups of sows and their offspring were offered feed either medicated with 60 ppm salinomycin or free of antibiotics, and their performance was compared. The number of piglets with diarrhoea, the duration of the diarrhoea, and the mortality of the piglets during the lactation period were markedly lower in the group given salinomycin. In addition, laboratory examinations showed that the numbers of carrier piglets and sows were reduced after treatment with Salinomycin. Finally, the sows treated with salinomycin lost less weight during the lactation period and weaned more and heavier piglets than the untreated sows. It was concluded that salinomycin incorporated in the diet can be used for controlling C perfringens type C infection in sows and their offspring.

Causes of mortality among sows in Danish pig herds

The likely causes of sow mortality in Danish pig herds were investigated in a sample of 598 of the breeding animals delivered to a large rendering plant in the winter seasons of 1992 and 1993. In 263 cases information about the circumstances of the death or euthanasia and the herd characteristics were available, including the size of the herd, its health status, the age at weaning, the method of feeding and the use of straw for bedding. For these animals the distribution of likely causes of death or euthanasia was: leg weakness, 28.5 per cent; problems related to farrowing and late pregnancy, 20.9 per cent; disorders of the digestive system, 17.1 per cent; disorders of the urinary system, 13.1 per cent; physical injuries, 10.7 per cent; and other disorders, 9.5 per cent. For the other 335 sows the distribution of likely causes of death was: leg weakness, 16.1 per cent; problems related to farrowing and late pregnancy, 10.7 per cent; disorders of the digestive system, 21.2 per cent; disorders of the urinary system, 15.2 per cent; other disorders, 15.0 per cent; and unknown causes of death, 21.8 per cent. According to the official statistics from Danish rendering plants, more than 60,000 carcases of breeding pigs were processed during 1992, corresponding to a mortality rate of 5 to 6 per cent in the sow herds. The mortality rate appeared to increase with increasing herd size, and in herds with more than 100 sows the mortality rate was three times the mortality in herds with fewer than 50 sows. Compared with previous reports, the proportion of disorders involving the gastrointestinal system has increased during the past 20 years. Gastric dilation is particularly common, probably as a result of the intensification of pig production and the associated changes in management practises. The use of straw bedding was marginally significant (P = 0.06) and associated with a low frequency of gastrointestinal disorders.

The effect of salinomycin on the control of Clostridium perfringens type-A infection in growing pigs

Salinomycin (SAL), an ionophorous polyether antibiotic with growth promoter properties in pigs, has proved to be effective in controlling swine dysentery, porcine intestinal adenomatosis, and porcine haemorrhagic enteropathy. This study examines the ability of SAL to control C. perfringens type-A infection in growing pigs under field conditions. For 2 months, two groups of weaned pigs were offered feed either free of antibiotics, or medicated with 60 ppm and 30 ppm SAL for the first and second month respectively, and were compared with regard to their performance. The results showed that, whilst treatment did not have an effect on the mortality of pigs, the duration of pig diarrhoea during the trial period has been markedly reduced in the SAL group. Laboratory examinations have additionally shown that the number of carrier piglets has been reduced by SAL medication. Finally, treated pigs gained more weight and had a better feed-conversion ratio than untreated pigs during the 2-month trial period. It was concluded that SAL at the registered dose range, used as performance enhancer, can be helpful in controlling C. perfringens type-A infection in growing pigs.

An outbreak of Aujeszky's disease in sheep in Northern Ireland

An outbreak of Aujeszky's disease occurred in a flock of 160 ewes which had been shorn and housed adjacent to pigs which were excreting Aujeszky's disease virus. The 29 affected sheep developed either the classical 'mad itch' signs associated with Aujeszky's disease in ruminants or signs of encephalitis. Aujeszky's disease virus was isolated from the central nervous system of the affected ewes. Five farm cats also became ill and died. Histological lesions of viral encephalitis were observed in one of the cats and Aujeszky's disease virus was isolated from its brain.

Discrimination of virulent and avirulent Streptococcus suis capsular type 2 isolates from different geographical origins

In an effort to relate the protein profile to virulence, proteins from the cellular fractions and from culture supernatants of Streptococcus suis capsular type 2 strains from different geographical origins were compared by using Western blots (immunoblots). The protein profiles of the cellular fractions were similar for the majority of virulent and avirulent isolates studied, with the exception of three virulent Canadian strains for which a 135-kDa protein was not detected. Examination of the culture supernatants revealed the presence of a 135-kDa protein in all strains except the same three virulent Canadian isolates. In addition, a 110-kDa protein was present in 14 of 16 virulent strains and not in avirulent isolates. When injected into mice, the 110-kDa protein induced an immunoglobulin G response and protected against infection with homologous and heterologous virulent strains. Four strains (1330, 0891, TD10, and R75/S2) that were avirulent in the mouse model of infection and four other strains (1591, 999, JL590, and AAH4) that were virulent in the mouse model were injected into pigs. All virulent strains reproduced the disease, and all avirulent strains failed to reproduce the disease (with the exception of transient lameness in one case and fever in another case). The 110-kDa protein therefore appears to be a reliable virulence marker and a good candidate for a subunit vaccine.

Productivity and profitability differences between pseudorabies-infected and pseudorabies-noninfected farrow-to-finish swine herds

Productivity and economic effects of pseudorabies were estimated for a mean-size, farrow-to-finish swine enterprise. A Delphi technique was used to elicit productivity effects from an expert panel. Enterprise budgets for pseudorabies-infected and noninfected herds were constructed by use of these productivity estimates, as well as by use of economic data from secondary sources. Data examined to determine effects on productivity included preweaning, nursery, and growing/finishing pig mortality; breeding hog mortality; feed conversion; labor; and veterinary services and medication expenses. Results indicated that profitability was lowered in infected herds by approximately $6/cwt of swine produced.

[Causes of pre- and perinatal piglet loss]

The main part of the extensive embryonic losses in swine is usually attributed to endogenous regulatory processes. Beyond that a lot of endogenous and exogenous noxae can induce embryonic and fetal death. 60-80% of the preweaning mortality occur during the perinatal period, i.e. the time direct before farrowing until the third day of life. Aetiology, which generally is due to noninfectious causes, and clinical symptoms of perinatal mortality are described.

The clinical recovery of fattening pigs from respiratory disease after treatment with two injectable oxytetracycline formulations

A double blind randomized clinical trial was performed with pigs suffering from clinical respiratory disease. The goal of the trial was to test the null hypothesis that the clinical recovery after treatment with two oxytetracycline injectables with different pharmacokinetic profiles (high peak concentration and low persistence versus low peak concentrations and long persistence) was similar. Fattening pigs (n = 529) were treated intramuscularly with either product A or product B at a dose of 20 mg OTC per kg b.w. when they showed signs of acute pneumonia, i.e., coughing, tachypnoea or dyspnoea combined with a rectal temperature of 40 degrees C or higher. When necessary, treatment was given again after 3 and/or 6 days. Both treatments resulted in a rapid fall in mean temperature and an improved clinical condition. In this trial no significant differences were found in clinical recovery between the two therapies as measured by group mean temperature, number of pigs requiring retreatment, and time to recovery. The conclusion that there was no important difference in clinical recovery between the treatment groups was made with a power of at least 90%.

[Postmortem findings in swine: non-selected submissions from hog cholera protection areas of 1992 versus selected submissions of 1991-1992]

This article presents a survey of death-causes of all spontaneously died pigs, n = 851, from a restricted area in the province of South Holland during a 2 1/2 months lasting hog-cholera epizoötic in 1992. 23 pigs from 5 submissions showed a positive IFT against hog-cholera virus. Those animals and pigs from sero-positive farms were excluded from this survey. The results of the post-mortems were compared with the post-mortem findings of the normally submitted, selected, animals in 1991 and 1992, n = 904 + 745, from the western parts of the Netherlands, in which the above mentioned province is situated. By means of classification of the animals in age-classes and of the post-mortem findings to disease or diseased organsystem, insight is gained in the prevalence of the various causes of death per age-class. No distinct differences were found between the findings in the groups of animals from 1991 and 1992. In the group of the hog-cholera-period comparatively more animals belonged to the neonatal and suckling period. In contrast to 1991-1992 the number of weaned and fattening pigs in the hog-cholera-group was lower. In both groups 40% of the death-causes was due to diseases of the digestive tract and 30% was a result of respiratory-tract infections. The third main cause of death in both groups was septicaemia and related diseases as endocarditis, pleuritis, peritonitis, polyserositis and polyarthritis. Comparison of the prevalence of infectious diseases per organsystem in successive age-classes demonstrated a similar tendency in the hog-cholera-group as in the year-groups 1991 and 1992.(ABSTRACT TRUNCATED AT 250 WORDS)

An analysis of the causes of piglet mortality in a breeding herd kept outdoors

The 229 piglets which died on an outdoor unit during a period of eight months were examined post mortem to determine the cause of death. The majority of the deaths (72 per cent) had occurred by the time that the litter was first inspected and of these 27 per cent had uninflated lungs and 53 per cent of the piglets born alive had no food in the stomach. Seventeen per cent of the stillborn pigs were of type I and 83 per cent were of type II. It was impossible to identify stillborn piglets reliably from their external appearance alone. At all ages, crushing was the most common cause of death (72 per cent of liveborn piglets). Six per cent of the corpses of the piglets had been damaged by birds, and attacks on live piglets occurred in the later stages of the study.

An ellipsoid farrowing crate: its ergonomical design and effects on pig productivity

An ellipsoid farrowing crate was designed and compared to the conventional rectangular crate with regard to its effect on sows' production traits. The main features of this crate are its oval horizontal frame and bowed vertical bars. Thirty-two sows farrowed in each system. Those in the ellipsoid crates raised 318 pigs and those in the rectangular crates raised 304. Stillbirth rate was lower in the ellipsoid crates than in the rectangular crates (P < .05). Among pigs born live, no significant difference due to crate was found on the deaths by crushing, infection, and other causes. The overall pigs' weaning rate from total births was also similar in both crates (P > .05). The daily weight gains of pigs for the 1st wk in the ellipsoid crate did not differ from those of pigs in the rectangular crates (P > .05) but were higher for the period from d 7 to d 21 (P < .05). The ellipsoid crate allowed the sow to turn around and have more freedom to move. However, the increase in sow movement did not cause a higher pig crushing rate than that in the traditional crate (P > .05). Behavioral observations also showed that the ellipsoid farrowing crate permitted easier visual and tactile contact of dams with their pigs and offered pigs better access to the sow's teats.