猪场母猪与仔猪猪圆环病毒2型感染情况调查

为了解目前母猪和仔猪猪圆环病毒2型(PCV2)感染情况,本试验对来自于15个猪场的85份母猪血清和29个猪场的55份仔猪可疑病料(脾脏、淋巴结、肾脏等),分别采用间接ELISA和PCR法进行PCV2抗体和病毒核酸检测。结果显示,在15个猪场中,1个猪场母猪抗体呈阴性,其他14个猪场母猪抗体均呈阳性,猪场PCV2阳性检出场为93.3%(14/15),85份母猪血清抗体总阳性率为75.3%(64/85)。29个猪场的仔猪,PCV2核酸检测阳性猪场为19个,猪场阳性率为65.5%(19/29),55份仔猪可疑病料病毒核酸检测总阳性率61.8%(34/55)。可见,母猪和仔猪感染PCV2相当普遍。对母猪群PCV2抗体阳性率及其仔猪群病毒核酸阳性率进行比较发现,母猪群PCV2抗体阳性率越高其仔猪群病毒核酸阳性率却越低。     

Fetal infections and antibody profiles in pigs naturally infected with porcine circovirus type 2 (PCV2)

The aim of this study was to describe early infections with porcine circovirus type 2 (PCV2) in naturally infected piglets and the piglets' serologic profiles. A total of 20 sows (15 PCV2-vaccinated and 5 unvaccinated) and 100 newborn piglets were studied. Colostrum and serum of the sows and serum of the presuckling piglets were obtained on the day of parturition. Milk samples were collected on day 20 postpartum. Blood samples were taken and the piglets weighed on days 1, 20, 42, 63, and 84 postpartum. Colostrum and milk were evaluated for infectious PCV2 and for PCV2 total antibody (TA), neutralizing antibody (NA), and IgA. Serum samples were evaluated for PCV2 TA, NA, IgA, IgM, and DNA. The sows had high levels of TA and NA in serum and colostrum; however, 11 and 5, respectively, of the 20 colostrum and milk samples contained infectious PCV2. In the serum, PCV2 DNA and IgM were detected in 17 and 5, respectively, of the 20 sows. Nine piglets were born with PCV2 antibodies, which indicates in utero transmission of PCV2 after the period of immunocompetence (> 70 d of gestation). On day 1 postpartum, PCV2 DNA was detected in 29 of the 100 serum samples from the piglets. There was no difference between the weights of viremic and nonviremic piglets throughout the study. In conclusion, even on farms with sows that have high PCV2 antibody titers, vertical transmission of PCV2 may occur, resulting in piglet infection.     

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.     

Immunoglobulins in piglets from sows heat-stressed prepartum

Sows were subjected to moderate heat stress in a chamber (32 C) from d 100 of pregnancy until less than 8 h before delivery of first piglet, while control sows were in a thermoneutral chamber (21 C) or farrowing house (22 C). Blood serum and colostrum at parturition of heat-stressed sows and their piglets' serum at birth had elevated cortisol concentrations. Total protein, globulin and immunoglobulin G (IgG) concentrations in sow serum tended to decrease as parturition time was approached; albumin did not change. Total protein and IgG concentrations in colostrum at parturition and in milk 24 and 48 h later tended to be lower in heat-stressed sows. Concentrations of these four protein fractions (total, globulin, IgG and albumin) in piglet serum at birth did not differ among treatment groups, but soon after colostrum ingestion they increased markedly in all groups. Therefore, in all groups total protein remained constant while globulin and IgG decreased. Globulin concentration on d 1 was lowest in piglets from heat-stressed sows, but its rate of decrease after d 1 was not affected by sow treatment. Immunoglobulin G concentration was 11 mg/ml lower, but its rate of decrease through postnatal d 20 was slower in piglets from heat-stressed sows than in those from control sows; a 10-mg/ml difference in IgG concentration on postnatal d 1 has been associated with increased preweaning mortality in piglets. Higher cortisol concentration in serum and lower IgG in colostrum of sows under heat stress was associated in their piglets with higher serum cortisol at birth and lower serum IgG for the first 20 d postnatum.     

Sow porcine circovirus type 2 (PCV2) status effect on litter mortality in postweaning multisystemic wasting syndrome (PMWS)

Previous studies have described a "litter effect" associated with mortality in postweaning multisystemic wasting syndrome (PMWS) affected farms. The main objective of this study was to evaluate litter mortality in different PMWS affected farms and to characterize it in relation to three variables of the sow: parity, porcine circovirus type 2 (PCV2) infectious status and PCV2 antibody titres. The study was performed in seven farms that experienced PMWS in nurseries and/or fattening areas. Fifteen sows from each farm were randomly selected from the same farrowing batch. Serum samples were analyzed for antibodies to PCV2 and for genomic detection of PCV2. Four piglets from each sow (60 piglets per farm) were selected and ear-tagged at birth. Out of 420 initial piglets, 104 (25%) died. Sixty three of them (60%) were necropsied, and 40 (63%) diagnosed as PMWS based on case definition criteria. Our results show that sow PCV2 viremia was significantly related to piglet mortality since more piglets per litter died from viremic than from non-viremic sows. Additionally, a significantly greater proportion of animals died from sows that had low antibody titres against PCV2 (39% vs. 18% from sows with medium to high antibody titres). The present study, of exploratory nature, confirms previous results and further characterizes the so called "litter effect" by establishing that the sow PCV2 status had a significant effect on litter mortality in PMWS affected farms.     

猪圆环病毒2型感染的血清学分析

应用间接免疫荧光技术 ,测定了浙江省内 4 4个猪场 2 0 0 0～ 2 0 0 2年间的 2 0 39个血清样本 ,对不同地区、年龄和品种猪的血清学数据进行了系统分析。结果显示 ,浙江省 4 4个猪场均有猪圆环病毒 2型 (PCV2 )感染 ,猪场的感染率为 10 0 % ,全省猪的 PCV2感染的平均血清阳性率为 5 8.31% ,其中种猪感染的血清阳性率为 5 9.38% ,断奶后猪感染的血清阳性率为 5 6 .6 5 %。长白种猪感染的血清阳性率为 4 4 .83%、长白仔猪感染的血清阳性率为 6 4 .2 8% ,明显高于大约克和杜洛克种猪和仔猪的感染率。 PCV2感染的血清阳性率高的种猪和仔猪群 ,其 PRRSV和 Pr V的抗体阳性率低。这些结果说明 ,PCV2在猪群中的感染非常普遍 ,不同品种猪对 PCV2的易感性不同 ,PCV2的感染可降低猪群对疫苗的免疫应答     

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.     

Relationship between postnatal piglet mortality,environmental factors and management around farrowing in herds with loose-housed,lactating sows

Abstract

The objective of this study was to investigate management routines and environmental factors influencing postnatal piglet mortality in commercial herds with individually loose-housed sows. Last year production records from 39 herds were used. We gathered information on specific routines as well as environmental factors by visiting every farm once. Herds practising moderate roughage feeding during pregnancy tended to have lower piglet mortality (p=0.06). Use of farrowing rails along all the sides of the pen resulted in lower piglet mortality than when no rails were present (p<0.01). Herds that hardly used any litter in the sow area at the time of farrowing had significantly higher piglet mortality than herds that used a moderate or large amount (p<0.05). Helping the piglets to obtain colostrum immediately after birth also reduced mortality (p<0.05), whereas other routines such as shutting the piglets inside the creep area while feeding the sow did not have any significant effect.     

Infectivity of porcine circovirus type 2 DNA in semen from experimentally-infected boars

Porcine circovirus type 2 (PCV2) is an economically important pathogen. It has been demonstrated that PCV2 DNA can be detected in boar semen by PCR; however, the biological relevance of this is unknown. The objectives of this study were to determine if semen positive for PCV2 DNA is infectious (1) in a swine bioassay, or (2) when used for artificial insemination. For the first objective, 4-week-old pigs were inoculated intraperitoneally with PCV2 DNA-negative (bioassay-control; n = 3), PCV2a DNA-positive (bioassay-PCV2a; n = 3), or PCV2b DNA-positive (bioassay-PCV2b; n = 3) raw semen, or PCV2 live virus (bioassay-positive; n = 3), respectively. Pigs inoculated with PCV2 DNA-positive semen and PCV2 live virus became viremic and developed anti-PCV2 antibodies indicating that the PCV2 DNA present in semen was infectious. For the second objective, three Landrace gilts were inseminated with PCV2 DNA-negative semen (gilts-controls) from experimentally-infected boars, and six gilts were artificially inseminated with semen positive for PCV2a DNA (gilts-PCV2a; n = 3) or PCV2b DNA (gilts-PCV2b; n = 3). Serum samples collected from the gilts in all groups remained negative for anti-PCV2 antibodies for the duration of the experiment. In addition, fetal serum samples from all 105-day-gestation fetuses were negative for anti-PCV2 antibodies or PCV2 DNA. Under the conditions of this study, PCV2 DNA-positive semen was not infectious when used to artificially inseminate gilts; however, it was demonstrated to be infectious in a swine bioassay model and therefore is a potential means of PCV2 transmission amongst swine herds.     

Clinical signs and their association with herd demographics and porcine reproductive and respiratory syndrome (PRRS) control strategies in PRRS PCR-positive swine herds in Ontario

The purposes of this study were to describe the clinical signs observed in PRRS positive herds during a porcine reproductive and respiratory syndrome (PRRS) outbreak in Ontario and to determine associations between these clinical signs and herd demographics and PRRS control strategies. All PRRS polymerase chain reaction-(PCR)-positive submissions to a diagnostic laboratory between September 1, 2004 and August 31, 2007 were identified (n = 1864). After meeting eligibility requirements and agreeing to voluntary study participation, producers from 455 of these submissions were surveyed for information on clinical signs observed in their herds, herd demographics, and PRRS control strategies used in their herds at the time that the PCR-positive samples were taken. Larger herd size was associated with an increased risk of reporting abortion, weakborn piglets, off-feed sows, and sow mortality in sow herds, and with an increased risk of reporting mortality in finishing herds. When disease control strategies were examined, use of a commercial PRRS vaccine in sows and gilts was associated with a decreased risk of reporting weakborn pigs and high pre-weaning mortality, while the use of serum inoculation in breeding animals was associated with an increased risk of reporting off-feed sows and sow mortality. Providing biofeedback of stillborn/mummified piglets, placenta or feces to gilts was associated with an increased risk of reporting respiratory disease and mortality in finishing pigs while all-in/all-out flow in farrowing rooms was associated with an increased risk of reporting sow mortality and weakborn piglets.     

Post-weaning multisystemic wasting syndrome (PMWS) clinical expression under field conditions is modulated by the pig genetic background

Post-weaning multisystemic wasting syndrome (PMWS) is a worldwide distributed disease of multifactorial origin and porcine circovirus type 2 (PCV2) has been identified as its essential infectious aetiology. Pig genetic background has been pointed to influence disease expression. In the present study, three different boar lines, namely A (100% Pietrain), B (50% Large White × 50% Pietrain) and C (25% Large White × 75% Duroc), were used to inseminate sows from the same genetic line (37.5% Large White × 37.5% Duroc × 25% Landrace) located on two PMWS-affected farms (farm-1 and farm-2). The PMWS clinical expression of their offspring was studied from weaning to slaughter, evaluating three parameters: total post-weaning mortality (PWM), PWM associated to PMWS (PMWS-PWM) and body weight (BW) evolution. The effect of other variables potentially related with PMWS, including sow and piglet PCV2 exposure, sow parity, piglet gender and piglet BW at weaning, were also considered in the study design. Overall, a total of 6.5% PWM and 4.3% PMWS-PWM occurred in the monitored farms. Pigs from boar line C showed the highest PWM (16.3%) and PMWS-PWM (12.4%), and the lowest BW; pigs from boar line A showed the lowest PWM (1.8%) and the highest BW. Furthermore, PWM was also higher in piglets from farm-2 and from multiparous sows. In farm-2, PMWS-PWM was higher in piglets from multiparous sows. Finally, BW was influenced by interactions between genetics and both farm and pig age, and was lower in piglets from farm-2. This study represents a consistent observation of the genetic background effect on PMWS clinical expression under field conditions.     

The effects of transplacental porcine circovirus type 2 infection on porcine epidemic diarrhoea virus-induced enteritis in preweaning piglets

The effects of transplacental porcine circovirus type 2 (PCV2) infection on porcine epidemic diarrhoea virus (PEDV)-induced enteritis were examined in neonatal piglets. Six pregnant sows were randomly allocated to an infected (n=3) or control group (n=3). Three pregnant sows were inoculated intranasally with 6 mL of tissue culture fluid containing 1.2 x 10(5) tissue culture infective doses 50% (TCID(50))/mL of PCV2 strain SNUVR000470 three weeks before the expected farrowing date. Three control pregnant sows were similarly exposed to uninfected cell culture supernatants. Thirty piglets from PCV2-infected sows were randomly assigned to two groups (A and B) of 15 piglets each. Another 30 piglets from noninfected sows were randomly assigned to two groups (C and D) of 15 piglets each. The piglets in groups A and C were dosed orally at three days of age with 2mL of virus stock (1 x 10(6.5) TCID(50)/mL) of the PEDV strain, SNUVR971496, at the third passage. The mean villous height and crypt depth (VH:CD) ratio in PEDV-infected piglets from PCV2-infected sows (group A) were significantly different from those of the PEDV-infected piglets from PCV2 negative sows (group C) at 36, 48, and 72 h post-inoculation (hpi) (P<0.05). In PEDV-infected piglets from PCV2-infected sows (group A), significantly more PEDV nucleic acid was detected in the jejunal tissues (P<0.05) at 24 hpi than in the same tissues of the PEDV-infected piglets from PCV2 negative sows (group C). Thereafter, at 36, 48, 60, and 70 hpi significantly more PEDV nucleic acid (P<0.05) was detected in the jejunal tissues of the PEDV-infected piglets from PCV2 negative sows (group C) than those of the PEDV-infected piglets from the PCV2-infected sows (group A). It is concluded that the clinical course of PEDV disease was markedly affected by transplacental infection of PCV2.     

Prevalence of infection with porcine circovirus-2 (PCV-2) and porcine reproductive and respiratory syndrome virus (PRRSV) in an integrated swine production system experiencing postweaning multisystemic wasting syndrome

The objective of this study was to evaluate the prevalence of infection with porcine circovirus-2 (PCV-2) and porcine reproductive and respiratory syndrome virus (PRRSV) through a longitudinal study in an integrated swine production system (7 farms) experiencing postweaning multisystemic wasting syndrome (PMWS). Risk factors for PCV-2 infection and for PCV-2 and PRRSV coinfection were also evaluated. Fifteen sows from each herd and 4 non-cross-fostered piglets from each sow were randomly selected at farrowing and ear-tagged at birth. Serum samples were analyzed for antibodies to PCV-2 and for detection of the PCV-2 and PRRSV genomes. Statistical analyses involved 2 approaches. The 1st approach characterized the dynamics of PCV-2 infection and their relationship with PRRSV infection. The 2nd approach analyzed the probability of being infected by PCV-2 or by both PCV-2 and PRRSV through a generalized linear mixed model incorporating sow and farm characteristics. At the 1st sampling time (1 wk of age), there was a significant relationship between sow PCV-2 infection and piglet PCV-2 infection (P < 0.0001). The risk of PCV-2 and PRRSV coinfection was 1.85 times greater in piglets from a sow with low titers of PCV-2 antibodies than in piglets from sows with medium to high titers (P = 0.03) and was 2.54, 2.40, and 2.02 times greater, respectively, in piglets from primiparous sows, PCV-2-infected sows, and farms in an area of high pig density than in piglets from sows of higher parity (P = 0.004), noninfected sows (P = 0.04), and farms in a low-density area (P = 0.09).     

Effect of supplementing sows' feed with alpha-tocopherol acetate and vitamin C on transfer of alpha-tocopherol to piglet tissues, colostrum, and milk: aspects of immune status of piglets

The aim of this study was to investigate the effects of dietary supplementation of sows with alpha-tocopherol acetate (ATA) and vitamin C on deposition of alpha-tocopherol (AT) in piglet lymphoid organs, such as bone marrow, thymus, and spleen at birth and at weaning, as well as on indicators of immune response in piglets. Sows were given the following treatment diets: control, vitamin C 10 g/day, ATA 500 mg/kg feed, and combined vitamins (ATA 500+Vit-C 10). Supplementation with vitamins started at the beginning of pregnancy and lasted until weaning at 21+/-3 days of age. AT was determined in colostrum, milk, piglet plasma (cord blood) and tissues at birth and on day 21. Immunoglobulins were measured in piglet plasma, milk, and colostrum. Lymphocyte proliferation in response to PHA and ConA was determined in sow and piglet blood. ATA supplementation resulted in a significant increase (P<0.001) in the AT content of colostrum, milk, piglet plasma, liver, thymus, bone marrow, and spleen at weaning. The AT content of colostrum and milk significantly (P<0.001) influenced the AT content of piglet plasma and tissues at weaning (day 21). Total Ig and IgG concentrations in piglet plasma were significantly increased in piglets given the combined vitamin treatment. No effect of AT supplementation was observed on IgG and IgA in colostrum and milk. In sows, vitamin C given alone significantly increased lymphocyte response to ConA and PHA; whereas, in piglets, there was no significant effect of treatments on lymphocyte response to PHA and ConA.     

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.     

Effects of the Ratio of n-6:n-3 Polyunsaturated Fatty Acids in the Maternal Diet on Immunoglobulins, Fatty Acid Composition, and Performance of Lactating Sows and Suckling Piglets under Conditions of Low Maternal Energy Intake

This experiment was conducted to investigate the effects of different ratios of n-6:n-3 polyunsaturated fatty acids (PUFA) in sow diets on the performance of lactating sows and their piglets at low digestible energy intakes.Twenty-one pregnant Landrace sows were assigned to one of three diets from day 108 of gestation until weaning (26 to 29 d),containing n-6∶n-3 PUFA ratios of 3∶1,8∶1 and 11∶1.The effects on sow and litter production traits and on sow body condition were examined.There were no differences among treatments in daily feed intakes or in changes in sow weight and back-fat levels during lactation.Litter size,litter weight at birth and weaning and litter average daily weight gain were also unaffected by treatment.As expected,large differences were observed in n-6 and n-3 fatty acids in the colostrum and plasma of sows and piglets (P ＜ 0.01 ).The ratio of n-6∶n-3 PUFA the diet was positively correlated with those in colostrum,sow plasma and piglet plasma ( R2 =0.55,0.80 and 0.80,respectively).Sow plasma insulin and IGF-I levels at weaning were unaffected by the treatments.Plasma leptin ( P ＜ 0.05) concentrations were increased in sows fed the diet with a n-6∶ n-3 ratio of 8∶1.Immunoglobulin concentrations in colostrum were not altered by dietary treatment.Plasma IgG concentrations at d 14 were highest in piglets from sows fed the 8∶1 ratio of n-6∶n-3.Furthermore,this group had the highest IgA concentrations at day 21 of lactation compared with the other two groups ( P ＜ 0.05 ).In summary,our study demonstrated that at low digestible energy levels,altering the ratio of n-6∶n-3 PUFA in the diets for lactating sows affected immune components and the fatty acid composition of lactating sows and their piglets.Further studies are needed to examine whether higher levels of fat supplementation than those used in the present study ( 1.5％ ) can successfully enhance performance.     

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.     

The influence of additional fat in the diet of sows before and after parturition on piglet viability and performance

Two hundred and six mature sows were used to evaluate the effect of adding a total of 3 kg of fat to sow diets for an average of eight days before and seven days after parturition on piglet viability and performance.The addition of fat to the diet of sows had no effect on the percentage of piglets born alive, individual piglet birth weight, weight of the piglet at three weeks of age or the weaning to service interval in the sows. However, there was a significant increase in piglet survival (3.4%) between treated and control sows. Birth weight had a marked effect on piglet survival but there was no indication of a greater effect of added fat in the sows' diet on the survival of smaller piglets. A number of piglets were cross-fostered but fostering had no effect on piglet mortality. A comparison of the mortality of piglets born from sows receiving added fat and reared on controls and vice versa indicated that the major benefits of additional fat in the sow diet were effected in utero rather than via an increase in the quality of the sows' milk.     

Studies on immunoglobulins and trypsin inhibitor in colostrum and milk from sows and in serum of their piglets.

The concentrations of IgG, IgM, IgA and the specific sow colostrum trypsin inhibitor (SCTI) were measured by radial immunodiffusion in colostrum and milk samples from sows and in serum samples from their offspring during the suckling period. A clear time dependence was found for all the measured variates in both whey and serum. Statistically significant positive correlations were found between, on the one hand, concentrations of IgG and IgA, but not IgM, in sera from 39 suckling piglets 1 and 3 days old, and, on the other hand, concentrations of the same immunoglobulins and of the trypsin inhibitor in maternal colostrum (n = 7). Multiple regression analyses showed that at day 1 and day 3 the levels of both IgG and IgA in serum samples from the suckling piglets were positively influenced by both the SCTI and the IgG or IgA contents in maternal colostrum.     

Prevalence of Chlamydia infections in breeding sows and their importance in reproductive failure

To investigate the prevalence of chlamydial infection and their significance for reproductive disorders in sow breeding herds in Germany, blood samples of 1493 pigs were taken for a serological survey by enzyme-linked-immunosorbent-assay (ELISA). Antibodies to Chlamydiae were found in 33% of the samples, in all herds investigated responders could be detected. The rate of seropositive animals in different farms varied from 4.3% to 72.7%. The percentage of positive responders in the farms correlated positively with the occurrence of MMA-syndrome (mastitis, metritis, agalactia), return to oestrus and diseases of the piglets. Also these herds showed less weaned piglets per sow and litter. Comparison of seronegative and seropositive sows within single farms revealed also worse reproductive data for seropositive sows. A significant relationship could be found between farms with a high quota of sero-positive sows and poor hygiene status as well as poultry keeping. As a second step 124 cervical swabs and 9 aborted piglets were investigated for chlamydial antigen by capture-ELISA and polymerase chain reaction (PCR). Using the capture-ELISA for investigation only 3 probes with chlamydial antigen could be detected, however, examination by the more sensible PCR gave positive results in 50% of the probes. 20% of the PCR-positive animals were clinically healthy sows, 80% of the PCR-positive probes originated from sows with reproductive disorders. A significant relationship could be shown between PCR-positive probes and the incidence of abortion and litters with stillborn piglets and piglets with low viability. Swabs from 93 of the 124 sows were investigated as well for other bacterial pathogens of reproductive disorders. A high degree of micro-organisms of different species could be detected in 70% of the samples of sows with reproductive disorders and in 35% of the samples of clinically healthy sows. Species differentiation of the chlamydial antigen positive samples was done by southern blot hybridisation. Herewith C. psittaci could be diagnosed in all positive samples. Additionally 8 probes revealed a mixed infection with C. psittaci and C. trachomatis. The results of the present study show, that the prevalence of chlamydial infections in breeding herds is high and underline the importance of chlamydial infections for reproductive disorders. Single chlamydial infections as well as mixed infections with other pathogens must be considered.