Aspects of the transmission of protection against Mycoplasma hyopneumoniae from sow to offspring

The aims of this study were to describe the variation in concentration of antibodies to Mycoplasma hyopneumoniae in the serum and colostrum of sows, and to compare the amount of antibodies in colostrum with that obtained in the serum of the smallest piglets in a litter. In addition, the efficacy of the passive immunity in natural conditions was studied. The study was performed in a sow pool herd (600 sows) that was endemically infected with M. hyopneumoniae. Blood samples were collected from sows 19 days (n = 25) before and 3 days (n = 15) after farrowing, and a colostrum sample (n = 25) was collected on the day of farrowing. All samples were analysed for antibodies to M. hyopneumoniae with a monoclonal blocking enzyme-linked immunosorbent assay (ELISA). Twelve sows (48%) were high-responders with respect to antibody concentration in colostrum. The amount of blocking decreased in serum during the last weeks of pregnancy and 3 days post-farrowing it was only 53% of the level found in colostrum. At the age of 14 days, 30 of the smallest piglets were weaned. They were divided into three experimental groups, being the offspring of high-responding sows, low-responding sows, or a mix of high- and low-responding sows. The groups were transported to three separated isolation units and were followed until slaughter. At slaughter, lung lesions were not found. Nor could M. hyopneumoniae be demonstrated either by cultivation or by polymerase chain reaction. However, a significant increase in absorbance values, assessed by an indirect-ELISA, was demonstrated in groups established from low-responding sows. It was concluded that a high antibody level in colostrum appeared to protect piglets from M. hyopneumoniae.     

Regional eradication of Mycoplasma hyopneumoniae from pig herds and documentation of freedom of the disease

The objectives of this study were to 1) screen all sow herds in a region for M. hyopneumoniae, 2) to effectuate an eradication programme in all those herds which were shown to be infected with M. hyopneumoniae, and 3) to follow the success of the screening and the eradication programmes. The ultimate goal was to eradicate M. hyopneumoniae from all member herds of a cooperative slaughterhouse (153 farrowing herds + 85 farrowing-to-finishing herds + 150 specialised finishing herds) before year 2000. During 1998 and 1999, a total of 5067 colostral whey and 755 serum samples (mean, 25 samples/herd) were collected from sow herds and analysed for antibodies to M. hyopneumoniae by ELISA. Antibodies were detected in 208 (3.6%) samples. Two farrowing herds (1.3%) and 20 farrowing-to-finishing herds (23.5%) were shown to be infected with M. hyopneumoniae. A programme to eradicate the infection from these herds was undertaken. During March 2000, a survey was made to prove the success of the screening and the eradication programmes. In total, 509 serum samples were collected randomly from slaughtered finishing pigs. Antibodies to M. hyopneumoniae were not detected in 506 of the samples, whereas 3 samples were considered suspicious or positive. Accordingly, 3 herds were shown to be infected. One of the herds was previously falsely classified as non-infected. Two of the herds were finishing herds practising continuous flow system (CF). Unlike finishing herds which practice all-in/all-out management routines on herd level, CF herds do not get rid of transmissible diseases spontaneously between batches, for which reason a screening was made in the rest of the CF herds (total n = 7). Consequently, 2 more infected herds were detected. In addition to the results of the survey, a decreasing prevalence of lung lesions at slaughter (from 5.2% to 0.1%) and lack of clinical breakdowns indicated that all member herds were finally free from M. hyopneumoniae in the end of year 2000.     

Vaccination of sows against Mycoplasma hyopneumoniae with Hyoresp

The aim of the study was to investigate the serological reactions of pregnant sows to vaccination with Hyoresp. Further investigations were performed in the offspring of these sows to follow the dynamics of maternal antibodies and the reaction to vaccination at different points in time. The study was conducted in three farrow-to-finish herds endemically infected with M. hyopneumoniae. A total of 30 gilts and 31 sows were vaccinated 8 and 4 weeks ante partum with Hyoresp (Merial GmbH) or given phys. saline solution as a placebo. The offspring was divided into three groups receiving Hyoresp at 1 and 4 or at 4 and 8 weeks of age. The control group was treated with phys. saline solution at 1 and 4 weeks of age. Before vaccination, antibodies against M. hyopneumoniae were detected in 85% of the gilts and 68% of the sows, confirming the endemic infection of the herds. Vaccination of the sows induced a significant increase in the antibody concentration in serum within four weeks and enhanced the concentration of antibodies in the colostrum. As expected, significantly enhanced levels of antibodies were also detected during the first four weeks of life of the offspring of vaccinated sows. The piglets' serological reaction to vaccination at 1 and 4 weeks of age showed marked interferences with maternal antibodies, so that a reaction could be demonstrated only at 8 weeks of age. The serological reaction of piglets vaccinated at 4 and 8 weeks of age was much stronger than that of piglets vaccinated earlier. Surprisingly, the vaccination status of the sow had no effect on the serological response of the piglets in either vaccination scheme. Maternal antibodies are known to reduce the risk of M. hyopneumoniae infections in piglets. Vaccinating the sows against M. hyopneumoniae may thus be an option for farrowing-to-finish herds with an enhanced risk for infections due to ineffective separation of different age groups, poor gilt acclimatisation or high gilt replacement rates.     

Exploratory field study on Mycoplasma hyopneumoniae infection in suckling pigs

The present study focused on Mycoplasma hyopneumoniae (M. hyopneumoniae) detection by nPCR in nasal swabs of 507 suckling pigs. These animals came from 69 sows (from 1 to 8 parity number) of a farrow-to-finish herd with Enzootic Pneumonia (EP) problems at finishing stages. At 1 and 3 weeks of age (still in the farrowing units), nasal swabs and blood samples were taken from all piglets. Moreover, from these 507 animals, 37 randomly selected pigs were necropsied at 3 weeks of age. From those necropsied pigs, M. hyopneumoniae presence was tested in bronchial and tonsillar swabs. At 1 week post-farrowing, blood samples from sows were collected and used to detect M. hyopneumoniae antibodies. From the 69 analysed sows, 19 (27.5%) were seropositive. Global percentage of pigs with M. hyopneumoniae detection in nasal swabs at 1 and 3 weeks of age was 1.5% (8 out of 507) and 3.8% (19 out of 507), respectively. From these nPCR positive pigs, 89% (24 out of 27) were seronegative and 11% were seropositive. From necropsied animals, the pathogen DNA was detected in two pigs at bronchus level and in another pig at tonsil. In this study, sow parity was not statistically related with sow seropositivity and piglet colonization. These results confirm that M. hyopneumoniae infection may be detected not only in nasal cavities of naturally infected suckling piglets but also at their low respiratory tract airways. Our results suggest that M. hyopneumoniae detection in lower and upper respiratory tract could be an indicator that respiratory problems associated to EP may start relatively early in the production system. In consequence, sow-to-piglet and/or piglet-to piglet transmission in farrowing barns should not be underestimated.     

An abattoir survey of pneumonia and pleuritis in slaughter weight swine from 9 selected herds. III. Serological findings and their relationship to pathomorphological and microbiological findings

Blood samples from 777 pigs, originating from 9 different herds, were collected at slaughter and examined for antibodies to Mycoplasma hyopneumoniae and Actinobacillus (Haemophilus) pleuropneumoniae by the indirect hemagglutination assay (IHA) and the complement fixation (CF) test, respectively. Results were compared to pathological and microbiological findings. Antibodies to M. hyopneumoniae in positive titers of 1/80 or higher were found in 62% of the samples. The relationship between positive IHA titers to M. hyopneumoniae and gross findings indicative of enzootic pneumonia of pigs (EPP), histological findings indicative of EPP, the isolation of M. hyopneumoniae and the demonstration of M. hyopneumoniae by indirect immunofluorescent testing ranged from 64% to 68%. No correlation was noted between positive IHA titers and the isolation of Mycoplasma flocculare. Positive antibody titers to A. pleuropneumoniae of 1/10 or higher were detected in 5% to 85% of the samples from individual herds. Positive titers to A. pleuropneumoniae serotype 2 were found in 71% to 79% of the sampled animals from herds with high frequencies of pneumonic lesions indicative of pleuropneumonia. In herds with low frequencies of pleuropneumonia, positive titers were recorded in from 0 to 4% of the tested pigs. However, no statistical association was found between pleuropneumonia and positive titers to A. pleuropneumoniae serotype 2 in individual animals. Twenty-one per cent of samples with positive CF titers to A. pleuropneumoniae showed antibodies to more than one serotype.     

Efficacy of mannanoligosaccharides additive to sows diets on colostrum, blood immunoglobulin content and production parameters of piglets

The present results suggest that mannanoligosaccharides (MOS) included in a sow nutrition may affect its immune system and humoral antibody production in colostrum and milk, and thus increase the piglet immunity at the postnatal period. The studies involved sows of the Polish Landrace breed mated with boars (Hampshire x Duroc). In each experiment, the sows were assigned to two groups: control and experimental (MOS). Each group consisted of 16 sows managed in pens (2 animals in each) during pregnancy, whereas at farrowing and lactation period they were placed in individual pens. The basal diet during pregnancy (PR-S) and lactation (LC-S) period contained wheat (40% in experiment I--groups 1 and 2) or triticale (40% in experiment II--groups 3 and 4), as well as barley, soybean meal, soybean oil and mineral-vitamin premix. Throughout both experiments, the sows from the experimental group had a dietary supplement of mannanoligosaccharides (MOS) preparation for 4 of weeks prepartum and 4 weeks of post partum period. A level of the MOS supplementation (8 g of MOS per sow daily) based on the recommendations of the manufacturer. Blood samples were collected from the sows on days 84 (the start of trial) and 110 of pregnancy, after farrowing, and on day 21 of lactation period, while from the piglets at birth and on day 21 of age. Colostrum was collected between 1-3, 12, 24 and 48 h after farrowing. The blood samples taken from sows and piglets as well as the samples of sow colostrum and milk were evaluated for the presence of IgG, IgA and IgM antibodies. The present study has provided considerable evidence that MOS supplementation of sows feedstuff before and after farrowing (4 weeks before and 4 weeks after) exerts a positive effect on IgG content in the colostrum and plasma of sows and following this on serum IgG level in the suckling piglets. Higher level of colostral (passive) immunity influences positively body weight gain and survival rate of the piglets at weaning.     

Farrowing induction induces transient alterations in prolactin concentrations and colostrum composition in primiparous sows

Hormonal changes involved in the farrowing process partly control the initiation of lactation. Inducing farrowing by injection of PG may alter the normal prepartum hormonal cascade. The aim of the study was to investigate the consequences of farrowing induction on colostrum yield and composition, as well as newborn piglet growth. Gilts were treated with 2 mg of alfaprostol on d 113 of gestation (induced farrowing, IF, n = 9) or were injected with 1 mL of a saline solution (natural farrowing, NF, n = 11). Colostrum production was estimated during 24 h, starting at the onset of parturition, based on piglet BW gains. Colostrum samples were collected during the 36 h after the onset of parturition. Blood samples were collected from sows as of d 112 of pregnancy until d 2 postpartum (d 0 being the day of parturition). Piglet blood samples were obtained at birth, on d 1, and on d 21. Litter size and litter weight at birth did not differ between groups (P > 0.10). Farrowing induction did not influence (P > 0.10) colostrum yield (3.96 ± 0.20 kg) or piglet BW gain during d 1 postpartum (116 ± 8 g). At the onset of farrowing (T0), lactose content in colostrum was greater in IF sows than in NF sows (P < 0.05), whereas colostrum ash and protein contents were less (P < 0.05) in IF sows. Concentrations of IgG in colostrum were similar in both groups of sows, whereas concentrations of IgA at T0 were less in IF than in NF sows (P < 0.01). Overall, endocrine changes in blood from d -2 until d 2 (cortisol, prolactin, progesterone, and estradiol-17β) were not altered by farrowing induction (P > 0.10), but 1 h after the injection of alfaprostol, IF sows had greater circulating concentrations of prolactin (P < 0.01) and cortisol (P < 0.10) than NF sows. The greater concentration of lactose in colostrum from IF sows could be attributed to this transient increase in prolactin and cortisol. At birth, concentrations of white blood cells were less in piglets born from IF sows (P < 0.01). On d 1 and 21, piglets from IF sows had similar IgG concentrations in plasma to piglets from NF sows (P > 0.1). In conclusion, farrowing induction at 113 d of pregnancy induced transient hormonal changes in sows and alterations in colostrum composition, without significantly affecting colostrum yield. It also modified some hematological variables of piglets at birth.     

High prevalence of porcine circovirus viremia in newborn piglets in five clinically normal swine breeding herds in North America

Porcine circovirus type 2 (PCV2) can be vertically transmitted resulting in fetal infection with or without clinical signs and lesions. The primary objective of this study was to assess the prevalence of intrauterine PCV2 infection in clinically normal newborn piglets in conventional pork production facilities. Five commercial breeding herds located in the U.S. and Mexico were included in the study. A total of 125 sows and 3-5 neonatal piglets per sow were arbitrarily selected. Blood and colostrum samples were collected from sows. Blood was collected from piglets prior to suckling. All samples were analyzed for the presence of anti-PCV2 IgG antibodies and presence and amount of PCV2 DNA. In addition, PCV2 DNA positive samples were further subtyped into PCV2a and PCV2b. All (125/125) sow colostrum samples and 96.8% (121/125) of the sow serum samples and 21.4% (107/499) of the piglet pre-suckle serum samples were positive for anti-PCV2 IgG antibody. The overall PCV2 DNA prevalence was 47.2% (59/125) in sow serum, 40.8% (51/125) in sow colostrum, and 39.9% (199/499) in pre-suckle piglet serum. In the PCV2 DNA positive samples, PCV2b was detected at a higher frequency (69.5% for sow serum, 84.3% for sow colostrum, and 74.4% for piglet serum) compared to PCV2a (18.6% for sow serum, 9.8% for sow colostrum, and 15.6% for piglet serum). Concurrent PCV2a and PCV2b infection was detected in 11.9% of the sow serum, in 5.9% of the colostrum samples, and in 10.0% of the piglet serum samples. In conclusion, an unexpectedly high prevalence of PCV2 viremia was detected in healthy sows (serum and colostrum) and their pre-suckle piglets in the five breeding herds investigated and PCV2b was more prevalent than PCV2a. This information adds to the knowledge of PCV2 infection in breeding herds.     

Colostrum yield and litter performance in multiparous sows subjected to farrowing induction

The consumption of colostrum at a low level can compromise the survival and growth of piglets. Therefore, this study aimed to evaluate the effect of farrowing induction on colostrum yield, IgG concentration and the survival and performance of piglets until the weaning. Sows of parity 3 to 7 were assigned into two groups: Control (n = 48), sows with spontaneous farrowing; and induction (n = 48), sows induced to farrow on day 114 of gestation with a PGF₂ analogue. Colostrum and blood samples were collected from the sows, at farrowing and 24 hr later. Blood samples from the piglets were collected at 24 hr after birth. The performance of the piglets was evaluated in a subsample of 28 litters from each group. All piglets were weighed at 7, 14 and 20 days of age. The farrowing length, the number of piglets born alive, stillborn piglets, weight at birth, litter weight at birth and colostrum yield were not significantly affected (p > .05) by farrowing induction. There was no difference between the groups (p > .05) in the percentage of sows with obstetric interventions. Serum IgG concentration, in both sows and piglets, and colostrum IgG concentration were similar between the groups (p > .05). Furthermore, survival rate, piglet weight and litter weight at 7, 14 and 20 days of age were also similar between the groups (p > .05). Therefore, it can be concluded that the farrowing induction performed on day 114 of gestation does not affect the colostrum yield, the IgG concentration in colostrum and serum of piglets, and the litter performance until the weaning.     

Intravenous infusion of glucose improved farrowing performance of hyperprolific crossbred sows

The sow at parturition is challenged with respect to energy status due to increases in energetic expenses associated with 1) nest building 2) uterine contractions, and 3) colostrum production. A previous study indicated that sows were depleted of glucogenic energy around farrowing. The aim was to investigate whether intravenous infusion of glucose from observed nest-building behavior to 24 h postpartum affected the farrowing kinetics and colostrum production in sows. Ten multiparous sows (DanBred landrace × DanBred Yorkshire) were fitted with a jugular vein catheter on each side (one for infusion and the other one for blood sampling). Sows were infused with either 0.9% saline (CON; n = 5) or 10% glucose (GLU; n = 5) solution at a constant rate of 125 mL/h. From day 108 of gestation, sows were fed once daily with 3.33 kg of a standard lactation diet. During farrowing, sows were monitored to register the onset of farrowing, time of birth, birth status (live or dead), sex, stillbirth rate (SR), and weight of newborn piglets. Farrowing assistance (FA) was provided when the birth interval exceeded 60 min. In late gestation, 1 mL of blood was collected every third hour for blood gas analysis and every sixth hour for harvesting plasma. During farrowing, 1 mL (for blood gas) and 9 mL of blood were collected at 0, 3, 6, 9, 12, 15, 18, 21, and 24 h in milk (HIM). Colostrum and milk samples were collected at 0, 6, 12, 18, 24, and 36 HIM and also at 3, 10, 17, and 24 d in milk. Compared with CON sows, GLU infusion decreased the SR (16.1% vs. 7.4%; P = 0.03), FA (21% vs. 9.0%; P = 0.01), and surprisingly also blood glucose at the onset of farrowing (5.53 vs. 5.09 mmol/L; P = 0.03), respectively. A tendency to higher plasma lactate at the onset of farrowing (P = 0.05) but decreased piglet survival from 0 to 24 h (P = 0.06) was also found for GLU sows. No effects of treatment on farrowing duration or mean birth intervals were found. Lactate in whole blood (P = 0.003) and plasma (P = 0.002) was increased for GLU sows as compared with CON sows during the colostrum period. No effect of GLU infusion was seen on colostrum and milk composition and yield. The increase in lactate was most likely due to a shift toward a greater proportion of glucose oxidation and insufficient O₂ supply to fuel uterine contractions. In conclusion, infusion of glucose reduced the frequency of SR and FA, and improved energy status of the sow which seems to be crucial to enhance total piglet survival.     

Antibody response to Mycoplasma hyopneumoniae infection in vaccinated pigs with or without maternal antibodies induced by sow vaccination

Vaccination with bacterins is an important tool for the control of Mycoplasma hyopneumoniae infection of pigs. Because such vaccination often involves piglets that have suckled M. hyopneumoniae antibody-positive dams it is important to understand the effect of pre-existing (passively acquired) antibody on vaccine-induced immunity. To investigate this issue experimentally, 20 sows that were seronegative for M. hyopneumoniae were selected from a M. hyopneumoniae-infected herd and then randomly allocated to one of four treatment groups (five sows/group): Group A, vaccinated sows/vaccinated piglets; Group B, vaccinated sows/non-vaccinated piglets; Group C, non-vaccinated sows/vaccinated piglets; Group D, non-vaccinated sows/non-vaccinated piglets. Sows (Groups A and B) were vaccinated 14 days before farrowing and seroconverted within the next 14 days. Conversely, none of the non-vaccinated sows was seropositive at farrowing. Piglets (Groups A and C) were vaccinated when they were 7 days of age. Regardless of treatments none of the piglets had any evidence of an active immune response until many of those of Groups A and C and a few of those of Groups B and D seroconverted after it had been shown that at least some pigs of all groups had been naturally infected with a field strain of M. hyopneumoniae. This pattern of immune responsiveness (i.e. the collective results of Groups A, B, C and D) suggested that vaccination of pigs had primed their immune system for subsequent exposure to M. hyopneumoniae, and that passively acquired antibody had little or no effect on either a vaccine-induced priming or a subsequent anamnestic response. According to the statistical analysis sow serological status did not interfere with the antibody response in early vaccinated piglets. In conclusion, the results pointed out that early vaccination of piglets may assist M. hyopneumoniae control independently from the serological status of sows.     

Effect of Mycoplasma hyopneumoniae colonization at weaning on disease severity in growing pigs

To determine whether Mycoplasma hyopneumoniae colonization at weaning in off-site weaning systems is associated with the severity of respiratory disease due to this agent in growing pigs, we studied 20 groups, each group representing a different week in production, in sow herds at 3 farms of 3000 sows each that had a prevalence of M. hyopneumoniae colonization at weaning higher than 5%. The calculated sample size for assessment at weaning was 39 piglets for each group under study; 39 litters were randomly selected, and 1 piglet was randomly selected from each litter for testing and ear-tagged. In total, 780 piglets were tested. The presence of M. hyopneumoniae in nasal swabs at weaning was established by nested polymerase chain reaction (PCR). All groups were followed until slaughter, at which time blood samples were collected from each ear-tagged pig to test for M. hyopneumoniae antibodies, bronchial swabs were collected for detection of M. hyopneumoniae DNA by nested PCR, and the lung lesion score and percentage of affected lungs in the same animals were calculated. Correlation analyses showed a positive correlation between colonization at weaning and all 4 dependent variables indicating infection at slaughter: average lung lesion score, percentage of affected lungs, presence of M. hyopneumoniae on the bronchial epithelium, and seroconversion. This study provides evidence that severity of the disease can be predicted by the prevalence at weaning in segregated systems. Therefore, strategies focused on reducing colonization at weaning seem to be important elements in the global control of M. hyopneumoniae in segregated production systems.     

Value of the clinical examination in diagnosing enzootic pneumonia in fattening pigs

The diagnosis of enzootic pneumonia at the herd level should be based on a combination of different methods. Currently, clinical examination is usually considered to be a low value method, particularly compared to the direct detection of Mycoplasma hyopneumoniae in lung lesions by PCR. The present study compared the value of accurate clinical examination (including the quantitation of coughing), PCR on bronchoalveolar lavage fluid, and serological testing of blood samples for the purpose of diagnosing enzootic pneumonia. The coughing index (average % of pigs coughing per minute of observation) was determined in fattening pigs from 59 herds, and ranged from 0% to 6.7% with a median of 2.4%. Five hundred and ninety bronchiolar lavage samples and 1179 serum samples were taken from pigs in those 59 herds and tested for M. hyopneumoniae specific DNA and antibodies, respectively. In herds where ?50% of lavage fluids were PCR positive, the likelihood of a higher coughing index was increased by 76% (OR: 1.76; 95% CI: 1.14-2.72) compared to herds with <50% of positive samples. For antibodies (determined by ELISA) a seroprevalence of ?50% increased the likelihood of a high coughing index by 50% (OR: 1.50; 95% CI: 1.03-2.20). In 78.1% of all herds with a seroprevalence of ?50% against M. hyopneumoniae, the PCR-prevalence and the coughing index were above the median (50% and 2.4%, respectively). It was concluded that in fattening pigs a quantitative assessment of the onset of coughing - typically dry and non-productive - improves the diagnosis of enzootic pneumonia and can occasionally substitute for the detection of M. hyopneumoniae by PCR.     

Serological diagnosis of enzootic pneumonia of swine by a double-sandwich enzyme-linked immunosorbent assay using a monoclonal antibody and recombinant antigen (P46) of Mycoplasma hyopneumoniae

To facilitate the control of enzootic pneumonia (EP) of swine caused by Mycoplasma hyopneumoniae, the complement fixation (CF) test has been used for the detection of M. hyopneumoniae antibodies. However, the CF test is a cumbersome and time-consuming technique and cross-reactivity are major drawbacks associated with this method. To circumvent these drawbacks, we have developed a double-sandwich enzyme-linked immunosorbent assay (ELISA), consisting of purified monoclonal antibody (Mab) against the 46 kDa surface antigen (P46) of M. hyopneumoniae and recombinant P46 protein expressed in Escherichia coli, for the detection of antibodies to M. hyopneumoniae in serum samples from pigs experimentally inoculated with M. hyopneumoniae and from naturally infected pigs, and compared the practical usefulness of ELISA using the CF test. In experimentally inoculated pigs, the CF and ELISA antibodies were detected at almost the same time, and a good correlation was demonstrated between the CF test and the ELISA. In a survey conducted on field samples, the seropositivity by ELISA in pigs of age 2-6 months was increased. At the time of slaughter, approximately 80% of the animals were seropositive for ELISA. However, a gradual decrease in the prevalence of ELISA positive samples was observed in sows with increasing parity. No correlation was seen between the results obtained with the two methods in the clinical samples. The CF test appears to have limited value for the diagnosis of EP in conventional herds because nonspecific reactions were frequently observed. Therefore, this ELISA is a useful alternative to the CF test currently used for the diagnosis of EP.     

Persistence of passively transferred antibodies in porcine Taenia solium cysticercosis. Cysticercosis Working Group in Peru.

We evaluated the presence and persistence of anticysticercal antibodies in piglets born to Taenia solium infected sows. Infected sows from a disease-endemic area of Peru were transported to a nondisease-endemic area and impregnated. Serum samples were collected from sows and piglets on Day 2 through Week 35 after birth. Using an immunoblot specific for cysticercosis, Ig isotypes to 7 cyst antigens were measured and quantified. Serum samples from the piglets contained detectable antibodies from Week 1 through Week 35 (27 weeks after weaning). The primary Ig isotype present in both sows and piglets was IgG. Antibodies did not appear in piglet serum samples until after suckling, demonstrating that anti-cysticercal antibodies are transferred solely via colostrum. Our data have shown that maternally transferred antibodies to cyst antigens may persist through much of a pig's life. Therefore, the presence of passively transferred antibodies must be considered in studies that examine the prevalence of cysticercosis in pigs. Furthermore, when designing control strategies for cysticercosis, careful evaluation and selection of sentinel pigs becomes a crucial component of sentinel selection.     

Seroprevalence and risk factors associated with seropositivity in sows from 67 herds in north-west Germany infected with Mycoplasma hyopneumoniae

Risk factors for the spread of Mycoplasma hyopneumoniae in sows have not been studied although vertical transmission from sows to their offspring is considered a significant risk factor in the development of enzootic pneumonia in growers and finishers. Seropositivity for M. hyopneumoniae in sows, as assessed by commercial ELISA, is a possible indicator of infection pressure among sows. The objective of this study was to estimate seroprevalence and associated risk factors of a sow being seropositive for M. hyopneumoniae. A cross-sectional study was carried out in 2578 sows from 67 herds in north-west Germany. Data concerning general herd characteristics, acclimatisation practices, indoor and outside contacts, as well as data describing the immediate local environment were collected during a herd visit via questionnaire. Blood samples were seropositive in 65% of the 2578 sows, and all herds had ≥14% seropositive sows. Data analysis was performed in two steps. First, univariate analysis of predictor variables for the risk of a sow being seropositive for M. hyopneumoniae was performed using chi-square test. Secondly, all variables associated with the risk of a sow being seropositive (P ≤ 0.25) were included in a multivariate model using a generalised linear model. The risk of a sow being seropositive for M. hyopneumoniae was increased in herds with two- or three-site production (OR 1.50), when piglets were not vaccinated against M. hyopneumoniae (OR 1.81), in herds with a 2-week farrowing intervals (OR 1.84) and in herds without all-in/all-out management of the farrowing units (OR 1.37). The lack of an acclimatisation period for replacement boars was also associated with the risk of a sow being seropositive (OR 2.10). The results indicate that M. hyopneumoniae seropositivity is common in sows in north-west Germany and is influenced by various management factors. It is recommended that evaluation of sow herd management should be included in any strategic health plan to control M. hyopneumoniae infection.     

Adsorption of colostral antibodies against classical swine fever, persistence of maternal antibodies, and effect on response to vaccination in baby pigs.

OBJECTIVE: To determine kinetics of antibody absorption, persistence of antibody concentrations, and influence of titers on vaccination of baby pigs with a vaccine against classical swine fever (CSF). ANIMALS: 15 sows and their litters. PROCEDURE: Farrowings were supervised. Initial time of suckling was recorded. In the first experiment, blood samples were collected at farrowing, 2 and 4 hours after suckling, and hourly until 10 hours after initial suckling. Samples were assayed for CSF antibodies, using a serum neutralizing (SN) test. A second experiment included 33 baby pigs vaccinated as follows: 10 prior to ingestion of colostrum, 18 between 1 and 4 hours after ingestion of colostrum, and 5 at 12 hours after ingestion of colostrum. Fourteen pigs were vaccinated when 7 weeks old, and 15 pigs were not vaccinated. At 10 weeks of age, pigs were challenge-exposed with virulent CSF virus. Blood samples were collected and assayed for CSF antibodies and p125 antigen and p125 antibodies. RESULTS: CSF antibodies were detected in pigs beginning 2 hours after suckling. Colostral antibodies persisted for > 7 weeks (half-life, 79 days). Vaccination of pigs before suckling provided effective protection from severe disease after challenge-exposure. However, vaccination of neonates with antibody titers was not effective, because 19 of 23 (82%) pigs succumbed after challenge-exposure. All pigs vaccinated when 7 weeks old resisted challenge-exposure, whereas all unvaccinated control pigs succumbed. CONCLUSIONS AND CLINICAL RELEVANCE: Vaccination before ingestion of colostrum conferred good protection against CSF in baby pigs. Vaccination of 7-week-old pigs that had decreasing concentrations of passively acquired antibodies was efficacious.     

Protection against neonatal Escherichia coli diarrhoea in pigs by vaccination of sows with a new vaccine that contains purified enterotoxic E. coli virulence factors F4ac, F4ab, F5 and F6 fimbrial antigens and heat-labile E. coli enterotoxin (LT) toxoid

The efficacy of a new vaccine against neonatal Escherichia coli diarrhoea in piglets containing purified F4ab, F4ac, F5 and F6 fimbriae and detoxified heat-labile toxin (LT) was tested in challenge experiments by the method described by the European Pharmacopoeia (3rd edn, EDQM, Council of Europe, Strasbourg, France). A group of 11 young sows from a herd without E. coli problems was vaccinated 6-8 and 2-4 weeks prior to expected farrowing and another group of nine young sows were non-vaccinated controls. Escherichia coli antibody titres were determined in serum samples taken from the sows before first vaccination and before farrowing and in colostrum samples. The newborn piglets were allowed to suckle colostrum from their mother immediately after birth. The piglets were marked with individually numbered ear tags. Approximately 12 h after birth, 118 piglets from vaccinated sows and 79 piglets from non-vaccinated control sows were challenged by oral instillation of 5 ml of a freshly prepared culture of one of the challenge strains [O8:K87:F4ab (LT+) or O149:K91:F4ac (LT+) or O9:K30:F5 or O9:K103:F6 respectively]. The challenge cultures contained as a mean 6.8x10(9) CFU/ml. After challenge the piglets were observed for 7 days and mortality and morbidity were recorded. Vaccinated sows developed significant levels of antibody titres in colostrum and serum. Control sows stayed at a low/seronegative level. The protective efficacy was excellent because 66.7-87.5% of the piglets from vaccinated sows remained without clinical signs after challenge. Only 0.0-28.0% of the piglets from non-vaccinated sows remained healthy and more than 47.1% of the piglets in this group died after challenge. It is concluded that the new vaccine is very effective in protection of piglets against neonatal E. coli diarrhoea.     

Re-modelling the Piggery Breeding Unit May Affect the Farrowing Rate

The objective of this retrospective cohort study was to clarify the effect of re-modelling the breeding unit on farrowing rate. The original study population included 63 sow herds that participated in the Finnish herd surveillance system. In these herds, the breeding units were re-modelled between 1995 and 2002. Information about the production system and other herd data for the last year before and the second year after re-modelling were available for 47 herds. The herds had an average of 68.5 (SD 45) sows per herd. Data were collected during one farm visit per herd. Initially, all herds had individual cages in their breeding units. The piggeries had either re-modelled their cages or switched to a group housing system with deep-litter, solid or slatted (partly or totally) floors. Farrowing rates were gathered from the national database, and data were tested with a linear regression model. Re-modelling did not have an effect on farrowing rate if initial reproductive performance of the herd was neglected. However, when farms were stratified according to performance prior to the beginning of study, namely into 'farms with initially high farrowing rate' (HF) and 'farms with initially low farrowing rate' (LF), the re-modelling had a significant effect on farrowing rate. In the HF farms, re-modelling caused a decrease in farrowing rate. Correspondingly, farrowing rate increased after remodelling in the LF farms. Farrowing rate was also influenced by mean parity of sows and by proportion of sows culled because of leg problems. This study could not show a profound impact of the design of the breeding unit on the fertility of the sow in the modern commercial production environment if the farm's reproductive performance before re-modelling was neglected. However, when initial performance was taken into account, re-modelling revealed significant, although varying effects on farrowing rate.     

Factors affecting the transfer of porcine parvovirus antibodies from sow to piglets

The aim of the study was to investigate the effects of a number of environmental, behavioural and biological factors on passive immunization of piglets as assessed by transfer of porcine parvovirus (PPV) antibodies (ab) from the colostrum of PPV vaccinated mothers to the serum of the piglets. Twenty primiparous sows were housed in pens with peat, straw and branches for nest building. Half the sows were prevented from achieving feedback from a completed farrowing nest by repeated removal of the nest from 10 to 12 h after nest building had begun, whereas the other half kept their nests. Sow serum PPV-ab titres were positively related to colostrum PPV-ab titres at birth of the first piglet (BFP) (P < 0.001). Litter average piglet PPV-ab titre was positively related to both sow serum and colostrum PPV-ab titres (both P < 0.001). In addition, in the individual piglets. PPV-ab titres were reduced as time from BFP to birth and time from birth to first sucking increased and time spent sucking decreased (all P < 0.01). There were no effects of treatment, time spent in lateral recumbency by the sow, number of times the sow stood or piglet weight on day 1 on piglet serum PPV-ab titres. Preventing prolonged farrowing, while at the same time ensuring the piglets' access to the udder, is important for transfer of maternal immunity. Measurements of specific antibodies in sow serum during the periparturient period and in piglet serum at 28 days of age may provide a practical tool for evaluating transfer of maternal immunity from sow to piglets.