Comparative investigations of a combined vaccine against parvovirus and erysipelas and corresponding monovaccines in different vaccination schedules. 1: Field trial]

In a field trial, the development of antibodies of a combined vaccine against the porcine parvovirus (PPV) as well as against swine erysipelas was compared with corresponding mono vaccines. Furthermore, these vaccines were used in different vaccination schedules. The tests were carried out on 109 gilts in three closed farms. In all gilts, a basic immunization repeated twice was carried out at the age of six months and at intervals of three weeks. The revaccination was carried out four months after the basic immunization with half of the animals, and six months after the basic immunization with the remaining gilts. Between the combined vaccine and the mono vaccine no significant differences in the development of antibodies against PPV could be found according to different vaccination schedules. The gilts having been vaccinated with the mono vaccine and boostered six months later showed significantly higher antibody titers against Erysipelothrix rhusiopathiae. Between the remaining vaccination groups no significant difference in the development of the antibodies against swine erysipelas could be found. On only one farm, a continuous decrease of antibody titers against PPV in case of altogether 238 non-vaccinated piglets until the sixth month of life could be observed. On the two other farms, an increase of antibody titers against PPV could be found at different points of time, which indicates an infection of the piglets. Between the individual vaccination groups no significant antibody titers against PPV could be measured in milk tests. With regard to the number of piglets born alive per litter, the number of piglets born dead per litter and the number of mummies, a significant difference could neither be found between the vaccination groups 1-4.     

Verification of peroral vaccination of pigs against enteropathogenic strains of Escherichia coli

In a large herd of pigs where the parenteral immunisation of pregnant sows by polyvalent vaccine against enteral coliinfections of new-born piglets was performed successfully for several years, an increased occurrence of diseases and mortality of sucking piglets was observed. After screening tests in the herd, six strains of E. coli, differing from the strains contained in the commercial vaccine, were isolated. The obtained strains were employed for preparation of peroral vaccine for sows by means of the modified method after Kohler. In two cycles of sows (48 animals in experimental group and 60 animals in control group), this method was compared with the effectiveness of the commonly used commercial polyvalent parenteral vaccine against enteral E. coli infections of new-born piglets (manufactured by Bioveta, Ivanovice in Haná). In experimental sow groups vaccinated perorally by the new vaccine, the number of live-born piglets increased by 0.475 piglet per litter, the number of reared piglets up to the age of 28 days by 0.904 piglet per litter and the mortality till the age of 28 days decreased by 6.1% as compared with the control vaccinated by commercial vaccine. The results were not statistically significant. The advantages and disadvantages of both vaccination methods are discussed.     

Influence of long-term vaccination of a breeding herd of pigs against PCV2 on reproductive parameters

The objective of the study was to evaluate an efficacy of sows vaccination protocols in the herd with serious problems affecting efficacy of reproduction. The study was performed in a large pig herd with about 1200 sows. Before vaccination against PCV2, farrowing rate in this farm was about 65%. Sows, boar and replacement gilts were immunized using Circovac vaccine (Merial, France) according to producer's recommendations. Parameters of production were analyzed since 2007 until 2010 in selected batches of sows inseminated at the same weeks of the year (17th, 18th, 19th and 20th) to eliminate seasonal variability. In total, 940 sows were subjected to the study. No significant changes in management during these years were introduced. The applied protocol of sow herd long-term vaccination proved to be very efficient. All measured production parameters: reproduction rate, number of piglets born alive, birth weight of piglets and number of piglets weaned per a litter improved after implementation of immunization program. Moreover, further improvement was observed with vaccination in the following reproduction cycles. The most spectacular effect of vaccination regarded average farrowing rate that increased from 64.76% in control group to 86.93% after basic vaccination. Two years after implementation of vaccination program this parameter reached 93.6%. Number of piglets weaned per sow per a litter improved from 10.31 to 11.74 after one year of vaccination and remained relatively stable through the following year. Simultaneously, the percentage of newborn piglets with birth weight < 1 kg decreased significantly (p < 0.05). To summarize, vaccination against PCV2 influenced positively the insemination rate, number of piglets born alive and weaned per litter as well as birth body weight and percentage of piglets weighing < 1 kg.     

Influence of the vaccination regime on the herd immune response for swine fever

Surveys in three areas with emergency vaccination programmes revealed that 86-94% of the pigs vaccinated in the initial mass campaign had developed an adequate antibody titre against swine fever as compared with 29-55% of the pigs involved in supplementary vaccination campaigns. The serological response of piglets born from immunised sows rose with the age of vaccination from 11% at 5-6 weeks to 42% at 7-8 weeks and 77% at 9-10 weeks. In piglets born from immunised sows, a 50% 'take' of the vaccine was not obtained before the age of 8-9 weeks. Re-vaccination of gilts born from immunised dams improved the immune status to almost the level observed after mass campaigns. To strengthen herd immunity in vaccination areas, the age of supplementary vaccination has been raised to 7-9 weeks, while breeding gilts are re-vaccinated when 6-7 months old.     

The pattern of endemic parvovirus infection in four pig herds

Serological surveys were conducted on the gilts and adult sows in 4 herds endemically infected with porcine parvovirus. The study assessed the influence of the type of management of breeders on the spread of virus infection and the influence of endemic parvovirus infection on reproductive parameters of the herd. The practice of holding gilts and sows in groups did not reliably promote infection or maintain a 100% level of active immunity amongst adult sows in 2 of 3 group husbandry herds. In the 4 herds, the prevalence of adult sows (greater than 12 months) with active immune haemagglutination inhibition titres (greater than or equal to 256) ranged between 44% and 100%, while between 0% and 100% of gilts (6 to 12 months of age) had active immune titres. Fully susceptible gilts older than 9 months of age held in groups, failed to become infected by 12 months of age on farms endemically infected with PPV. In 2 herds a continued low infection rate of gilts resulted in increasing the potential of breeding animals becoming susceptible to parvovirus infection as infected sows were replaced by noninfected gilts. In both herds, epidemics of parvovirus infection followed, which were characterised by an increase in reproductive failure. Parvovirus infection during the first 70 days of pregnancy reduced the average number of piglets born alive per litter by 1.6 piglets (p less than 0.05). This was due to the combined effect of more piglets being born dead per litter and an overall reduction in litter size.     

Exposure of sero-positive gilts to swine influenza virus may cause a few stillbirths per litter

Six pregnant gilts were purchased from a high health herd and were found to be serologically positive for swine influenza virus (SIV) subtype H3N2. Three of the gilts, at 80 to 82 days of gestation, were experimentally exposed a second time to the same SIV subtype--H3N2. No clinical signs resulted from the second exposure to SIV and hemagglutination-inhibition (HI) titers for SIV at 4 weeks postexposure were unchanged suggesting that the gilts had not been reinfected. However, the second exposure to SIV affected the number of pigs born alive. Each of the 3 litters from the twice exposed gilts suffered 2 or 3 stillborn piglets per litter. In contrast the 3 matched, sero-positive gilts that were not exposed to SIV (controls) had no stillborn piglets. These differences were statistically significant using a t-test for unequal variances (P = 0.0086). Sera from 2 of the stillborn piglets were negative for HI antibodies and there was no indication from the pigs born alive that the H3N2 virus had crossed the placenta.     

Porcine Parvovirus infection: review and diagnosis in a sow herd with reproductive failure

In a commercial swine herd a rise was noted during the summer of 1981 in the number of repeat breeders, mostly four to eight weeks after serving. During the autumn there was a decrease in the litter size at birth and an increase in the number of stillborn and mummified piglets. Several gilts and sows showed a seroconversion against Porcine Parvovirus (PPV), determined by the Haemagglutination Inhibition test (HI-test). Characteristic pathological findings were seen in some maturely stillborn and neonatally decreased piglets (up to an age of 28 days); hepatic congestion and necrosis, accummulation of fluid in body cavities, myocarditis, and encephalitis were the most prominent features. Serological tests for antibodies in blood samples of one sow and body fluids of two stillborn piglets were suggestive of Porcine Parvovirus as the aetiological agent.     

Clinical papers

In a commercial swine herd a rise was noted during the summer of 1981 in the number of repeat breeders, mostly four to eight weeks after serving. During the autumn there was a decrease in the litter size at birth and an increase in the number of stillborn and mummified piglets. Several gilts and sows showed a seroconversion against Porcine Parvovirus (PPV), determined by the Haemagglutination Inhibition lest (HI‐test). Characteristic pathological findings were seen in some maturely stillborn and neonatally deceased piglets (up to an age of 28 days); hepatic congestion and necrosis, accummulation of fluid in body cavities, myocarditis, and encephalitis were the most Prominent features. Serological tests for antibodies in blood samples of one sow and body fluids of two stillborn piglets were suggestive of Porcine Parvovirus as the aetiological agent.     

Estimation of lifetime productivity of female swine

OBJECTIVE: To develop estimates of lifetime productivity for breeding female swine calculated longitudinally during time in the breeding herd, and to compare estimates of lifetime productivity for female swine removed from the herd at different parities. DESIGN: Retrospective cohort study. ANIMALS: 9,416 breeding female swine from 29 herds. PROCEDURE: A frequency distribution for parity at the time of removal was generated. Estimates of lifetime productivity (lifetime nonproductive days [NPD], lifetime NPD as a proportion of herd life, total number of pigs born per litter weaned, number of pigs born alive per litter weaned, number of pigs weaned per litter weaned, number of NPD per year in the herd, number of litters weaned per year in the herd, and number of pigs weaned per year in the herd) were calculated for females with parity > or = 1 at the time of removal. RESULTS: For 58% of all females, parity at the time of removal was < or = 3. On average, 20.7% of herd life was spent in nonproductive activities, but the proportion of herd life that was nonproductive decreased significantly as parity at the time of removal increased. Number of NPD per year in the herd decreased and number of litters weaned per year in the herd and number of pigs weaned per year in the herd increased significantly as parity at the time of removal increased. CLINICAL IMPLICATIONS: Higher parity at the time of removal from the herd is associated with improved lifetime productivity for female swine. Parity at time of removal is commonly used as an approximation for lifetime productivity, but it does not take into account the impact of NPD, especially NPD during early reproductive cycles.     

Effect of vaccinating sows and their piglets on the development of Glässer's disease induced by a virulent strain of Haemophilus parasuis serovar 5

Ten pregnant gilts were divided into two groups of five and one group was vaccinated at 80 and 95 days of pregnancy with a commercial bacterin containing Haemophilus parasuis serovars 2, 3 and 5. Half the piglets born to each group of gilts were vaccinated at seven and 21 days of age with the same bacterin, and one week after they were weaned at five weeks, all the piglets were inoculated intratracheally with 10(6) colony-forming units of Hparasuis serovar 5. At slaughter, a significantly smaller percentage of the lungs of the pigs born to the vaccinated gilts was affected by pneumonic lesions, and significantly fewer of them had arthritic joint changes. The average daily liveweight gain of the pigs born to the vaccinated gilts was significantly greater than that of those born to the unvaccinated gilts, but the vaccination of the piglets had no effect. There was no significant difference between the feed conversion ratios of the four groups of piglets, and none between the average times they took to reach slaughter weight. The pigs born to the vaccinated gilts had higher ELISA titres to Hparasuis than those born to the unvaccinated gilts.     

A reduction in litter size on an ontario Swine farm

In a 200 sow herd, the litter size fell from an average of 10.5 pigs born alive per litter from January to June, to an average of 9.2 for the remainder of the year. Management changes during the first part of the year resulted in half the sows weaning litters at three weeks of age and half the sows weaning at four weeks of age instead of at six weeks as was previously done. The subsequent litter size was 9.3 pigs born alive per litter for three-week weaned sows compared to 10.0 for four-week weaning. The management of gilt breeding was also altered by the necessity to breed groups of 12 gilts in one-week periods of time and therefore a higher proportion of gilts may have been mated on their first estrus instead of their second or third estrus as had been the case. The difference in litter size of first parity sows between the first six months and the second six months was 1.1 pigs. Parvovirus infection may have been a factor contributing to the reduction in litter size amongst first parity sows; two groups of first parity sows experienced an increase in mummified piglets, a reduced far rowing rate, and smaller litter size. However, no attempt was made at diagnosing an infectious agent. Parity distribution remained relatively unchanged during the year and was not associated with the drop in litter size.     

Within-herd Use of Boar Semen at 5°C, with a Note on Electronic Monitoring of Oestrus

A system was designed to allow a small swine farm in a northern latitude to use its own boars for artificial insemination (AI) conveniently. Semen was collected twice weekly for 3 day use (days 0, 1 and 2), extended in an egg yolk extender and stored at 5°C. Farm personnel were trained to manage the entire AI programme. For simplicity all semen collected was used for insemination. In the first test 47 gilts and 15 sows were inseminated with semen from four boars. One boar was subfertile with a farrowing rate of 36%. The averages for the other boars ranged from 71 to 100%. Then semen was collected from seven boars and all was used to inseminate 70 gilts and 55 sows with 3 × 10⁹ or more sperm. Overall 63% farrowed an average of 10.1 piglets per litter. Litter size for sows was 1.5 piglets larger than for gilts. There was no difference in farrowing rate when more than 3 × 10⁹ sperm were inseminated. The feasibility of initiating a complete AI programme within a small herd using herd boars was established. However, selection of the boars, use of only high quality semen, and experience with detecting oestrus was required to increase the farrowing rate. The use of various agents to protect sperm against cold shock below 15°C is worthy of further investigation. A new type of electronic probe, which measures the conductivity of cervical mucus, could be helpful if a boar is not available for conventional detection of oestrus.     

Development of a vaccine preventing parvovirus-induced reproductive failure in pigs

SUMMARY An inactivated porcine parvovirus (PPV) vaccine for the prevention of PPV-induced reproductive failure in pigs was developed, using virus grown in cell culture, inactivated with beta-propiolactone and adjuvanted with aluminium hydroxide. The vaccine was tested for safety by subcutaneous injection into pregnant gilts. There were no signs of abnormal reactions nor evidence of PPV infection in the gilts or their foetuses when they were sacrificed 6 weeks after vaccination. To demonstrate that the vaccine was immunogenic, pigs were immunised either once or twice with 4 weeks between doses. Resulting antibody titres (haemagglutination inhibition — HAI) ranged from < 8 to 64 (geometric mean of 30) after one dose of vaccine, and from 128 to 512 (geometric mean 256) after two doses. To demonstrate that the vaccine was protective, antibody-negative gilts were vaccinated twice, with 4 weeks between doses, joined after the second dose, and were then infected with virulent PPV 40 to 50 days after joining. In litters from 10 vaccinated gilts, none of 93 foetuses showed evidence of PPV infection. In contrast, in litters from two unvaccinated gilts, all 13 foetuses showed evidence of PPV infection and 10 of these were mummified. The average number of live piglets per litter was 9.2 from vaccinated gilts and 1.5 from unvaccinated gilts. The vaccine was therefore considered to be effective in preventing PPV reproductive failure in susceptible gilts.     

Use of an enzyme-linked immunosorbent assay for detection of infection with pseudorabies virus on a herd basis.

The use of an ELISA that can differentiate between swine infected with pseudorabies virus (PRV) and swine vaccinated with a specific PRV vaccine was evaluated on an individual and herd basis, and a system for interpreting ELISA results on a herd basis was developed. In 17 herds, recently introduced replacement gilts, seronegative for PRV, were vaccinated with a thymidine kinase- and glycoprotein X (gpX)-deleted vaccine. After vaccination, blood samples were collected from these gilts approximately every 1 to 2 months for up to 19 months. Serum samples were analyzed for antibodies to gpX antigen, using a commercially available ELISA kit according to the manufacturer's protocol. Herd status was determined as positive, suspect, or negative, according to the serum sample:negative control (S:N) values of the samples collected from the herd. From the 17 herds, 130 evaluations were performed. On 49 (38%) of the 130 herd evaluations, 1 or more gilts had suspect test results. Additional testing was required in 19 (39%) of these 49 herd evaluations to determine the PRV infection status of the herd. Status of herds having gilts with suspect results and no positive results was usually negative after retesting. Herds having gilts with positive results were unlikely to have negative status after retesting.     

Vaccination against progressive atrophic rhinitis with a recombinant Pasteurella multocida toxin derivative.

Vaccination against progressive atrophic rhinitis using a purified recombinant derivative of the Pasteurella multocida toxin (PMT), was carried out. Ten pregnant gilts were vaccinated twice with the nontoxic derivative (dO) which apart from a lack of 121 amino acids had an amino acid sequence identical to PMT, while seven gilts were vaccinated with a purified, formaldehyde treated, native PMT and ten gilts served as non-vaccinated controls. The resulting piglets were inoculated intranasally with Bordetella bronchiseptica and toxigenic P. multocida. Among piglets from the nonvaccinated gilts all except one developed clinical atrophic rhinitis and 90% developed severe turbinate atrophy while only a few pigs in the vaccinated groups developed clinical or pathological signs of disease. Gilt colostra from the two vaccinated groups had similar mean anti-PMT titers and the mean titers in the offspring's sera from these groups were nearly identical throughout the study. No pigs born from unvaccinated gilts were seropositive until 8 wk of age (7 wk post-challenge) but 23% became seropositive at slaughter. The infection rate with toxigenic P. multocida in piglets and the total number of P. multocida colonies cultured from nasal swabs were significantly reduced at 5 wk and 8 wk of age in the vaccinated groups, when compared to controls. There was a significantly improved weight gain (greater than 9%) from birth to slaughter in offspring from vaccinated gilts. No significant differences in feed conversion rate or % lean meat were observed among the groups. The study showed the excellent immunoprotective properties of the nontoxic derivative of the PMT molecule.     

应用重组抗原预防猪囊虫病

应用２种重组抗原分别制成免疫刺激复合体疫苗各接种试验猪２次,间隔１４ｄ。第２次接种后７ｄ用有钩绦虫卵感染（２×１０４个／头）。感染后１１６ｄ,９头对照猪共发现１０６７个囊虫,平均１１８．６个／头;免疫Ａ组８头试验猪共发现囊虫５１０个,平均６３．８个／头,减虫率为４６．２％;免疫Ｂ组９头试验猪共发现囊虫８３个,平均９．２个／头,减虫率为９２．２％。在免疫Ｂ组猪体内发现的囊虫发育不全,虫体小,囊液少,囊膜较厚、不透明,呈乳白色,囊虫组织呈退行性病理变化,并伴有大量炎性细胞浸润。免疫动态监测发现,试验猪抗囊虫感染的免疫力主要取决于细胞免疫,而与体液免疫无关。试验猪血清循环抗原（ＣＡ）检测结果与剖检所见囊虫数量密切相关（Ｐ＜０．０１）。由此认为,ＣＡ检测是简便易行、效果可靠的现场实用技术。     

Protection against progressive atrophic rhinitis by vaccination with Pasteurella multocida toxin purified by monoclonal antibodies

Pasteurella multocida toxin was purified by affinity chromatography and inactivated by treatment with formaldehyde before use as a single component vaccine against progressive atrophic rhinitis in pigs. Twenty pregnant gilts which were vaccinated twice before farrowing with either low or high doses of the purified toxoid, developed dose-dependent positive serum and colostrum titres to the toxin and, unlike the progeny of 10 untreated control gilts, the offspring of the vaccinated gilts also had serum titres. These titres could be measured in blood samples taken for more than eight weeks from birth for most pigs born to gilts vaccinated with low doses and more than 12 weeks for pigs born to gilts vaccinated with high doses of the vaccine. All the piglets were inoculated intranasally with Bordetella bronchiseptica and toxigenic P multocida. The clinical and post mortem examinations of snouts revealed a significant reduction in the frequency and degree of conchal atrophy in the two groups of pigs from the vaccinated gilts compared with the pigs from control gilts. Clinically 90 per cent of the snouts of pigs born to vaccinated gilts appeared normal whereas only 28 per cent of the snouts of control pigs were not shortened or deviated at eight weeks of age. At slaughter 11 per cent of the pigs born to vaccinated gilts and 81 per cent of the control pigs had severe turbinate atrophy.(ABSTRACT TRUNCATED AT 250 WORDS)     

Spread of pseudorabies virus among breeding swine in quarantined herds.

In theory, pseudorabies virus (PRV) may be eliminated from any size of breeding herd by phased test and removal if replacement gilts are not infected with PRV, culling decisions are partially based on PRV status, and the cull rate is higher than the incidence rate of PRV. Annual cull rates are commonly at least 50%, but little information exists on the incidence of PRV within enzootically infected swine herds. The purpose of this study was to develop a method by which spread of PRV could be detected among breeding swine within enzootically infected herds and to determine the incidence of PRV infection in these herds. Data were collected from 17 herds that were quarantined for PRV and ranged in size from 120 to 1,100 sows. At each herd, within the first 5 days of introduction, a group of approximately 30 replacement gilts was identified, vaccinated with a glycoprotein X-deleted PRV vaccine, and blood sample was collected. The owner of 1 herd had a nonvaccinated breeding herd and elected to leave incoming gilts nonvaccinated. After vaccination, blood samples were collected every 1 to 2 months for an average of 13.6 months. Serum samples from vaccinated gilts were tested for antiglycoprotein X antibodies by a specific differential ELISA. Samples from nonvaccinated gilts were evaluated by serum neutralization test. Product-limit method was used to estimate the probability of not becoming infected with PRV. Spread was detected in 7 of 8 herds that had more than 400 sows and in 2 of 9 herds that had less than 400 sows.(ABSTRACT TRUNCATED AT 250 WORDS)     

母猪窝产活仔数与初生仔猪整齐度的相关性研究

本研究统计分析了苏钟猪纯系及其杂交系母猪窝产活仔数与初生仔猪整齐度间的相关性,结果表明,随着母猪窝产活仔数的增加,仔猪初生重的平均数逐渐降低,标准差逐渐升高,整齐度不断降低。纯系苏钟猪窝产活仔数与标准差存在正相关,差异达到显著水平 (P<0.05);与平均数存在负相关,差异达到极显著水平(P<0.01);杂交系苏钟猪窝产活仔数与标准差存在正相关,差异达到极显著水平(P<0.01);与平均数存在负相关,差异也达到极显著水平(P<0.01)。同时,不同产仔区间母猪窝产活仔数对仔猪初生重的标准差和平均数也存在较显著的影响,母猪窝产活仔数与初生仔猪的整齐度间存在一个较优的经济区间。     

Immunization of pigs against Streptococcus suis serotype 2 infection using a live avirulent strain.

Streptococcus suis capsular type 2 is still an important cause of economic losses in the swine industry. At the present time, vaccination of pigs against this infection is generally carried out with autogenous bacterins and results are equivocal. In this study, the protective effect of a live avirulent S. suis type 2 strain (#1330) which had induced a good protection in mice, was evaluated in swine. The experiment was performed in triplicate using 4 week-old piglets. A total of 15 piglets were vaccinated 3 times, 15 others were vaccinated 2 times, and 15 piglets were injected 3 times with sterile Todd-Hewitt broth. Using an indirect ELISA, an increase in the IgG response to S. suis antigens was noted in 27 of the 30 vaccinated piglets. On day 21 post-vaccination, all animals were challenged intravenously with a virulent S. suis type 2 strain (#999). In the 2 vaccinated groups, 26 animals were fully protected. Only 1 out of the 15 piglets vaccinated 3 times developed mild clinical signs. In the group vaccinated twice, 3 piglets showed clinical signs and 1 of them died after the challenge. In the control group, 7 animals died out of the 11 with clinical signs of infection. In conclusion, a protective immunity was observed in swine when using strain 1330. However, more studies are needed to assess the use of a live S. suis strain in a vaccine for pigs.