Abstract. An indirect fluorescent antibody (IFA) test was developed and standardized to detect and quantitate antibody for swine infertility and respiratory syndrome (SIRS) virus in swine sera. Test results were evaluated using sera of pigs infected both experimentally and naturally with SIRS virus. The IFA test used swine alveolar macrophage (SAM) monolayers prepared in 96-well microplates and infected with SIRS virus. The monolayers were incubated with test sera, washed, and stained with fluorescein isothiocyanate-labeled rabbit anti-swine IgG. After another wash step, the monolayers were examined under a fluorescent microscope. A noninfected SAM control well was included for each sample. The antibody titers for each serum sample were recorded as the highest serum dilutions with specific cytoplasmic fluorescence but no fluorescence in the control wells. To evaluate the test, sera of 4 6-week-old pigs that had been infected with SIRS virus, 2 contact pigs, and 13 experimentally infected sows were used. In the experimentally infected pigs, antibody was first detected at 7 days postexposure (PE) and peaked (1:256-1,024) between 11 and 21 days PE. All 13 sow sera were negative at time of infection but were positive (1:64-> 1: 1,024) at 14-26 days PE. Seven hundred twenty sera collected from 25 different swine farms with or without a history of SIRS were also tested. Of 344 sera from 15 swine farms with a clinical history of SIRS, 257 (74.7%) sera had IFA titers ≥ 1:4, whereas 371 (98.7%) of 376 sera from herds with no history of SIRS were negative. The present results indicate that the IFA is a useful test for the detection and quantitation of SIRS virus antibody in swine sera.Swine infertility and respiratory syndrome (SIRS) virus has recently been recognized as an important pathogen in the United States because the virus causes severe reproductive failure in pregnant sows and high mortality due to respiratory disease in young pigs. [1][2][3]8 A similar syndrome has been reported in several European countries, 4-7 and the causative agent, Lelystad virtus, 6 was identified. Antibody to the Lelystad virus has been detected by an immunoperoxidase monolayer assay (IPMA), 6 whereas a serum neutralization (SN) test was described for the detection of antibody to SIRS virus.2 The purpose of the present study was to develop a simple indirect fluorescent antibody (IFA) method for detection and quantitation of SIRS virus antibody in swine sera. The method was evaluated using sera of pigs experimentally infected with SIRS virus. Test results of field serum samples collected from 25 different farms with or without a clinical history of SIRS are also described.SIRS MN-lb isolate at the fifth passage level was prepared in SAM cells, and virus aliquots of 10 4.5 immunofluorescence infective dose 50 (IFID 50 )/ml were stored at -70 C. Materials and methodsPreparation of test plates. The SAM cells, either freshly prepared or stored at -70 C, were diluted at a concentration of 2 x 10 6 cells/ml in RPMI-1640 medium supplemented w...
A study was undertaken on a commercial swine farm to investigate methods of reducing perinatal mortality. During a 12-wk period, 251 sows and gilts were assigned randomly to one of four treatment groups in a 2 x 2 factorial design: 1) supervised/induced, 2) supervised/non-induced, 3) unsupervised/induced, and 4) unsupervised/non-induced. Supervised groups of sows and their litter were observed constantly for a minimum of 3 h before and until 3 d after farrowing. The onset of farrowing was induced with 250 micrograms of cloprostenol administered into the vulvo-vestibular mucosa. There was an increase (P = .012) in the number of pigs weaned from supervised (10.17 pigs/litter) relative to unsupervised group (9.44 pigs/litter). This increase was due to a reduction (P = .001) in both the number of stillborn pigs and the mortality of live-born pigs (P = .026). The latter resulted from fewer pigs that died (P = .003). Induction did not influence the mortality of pigs in the perinatal period in unsupervised groups. Induced sows farrowed an average of .43 d earlier than non-induced sows (P = .029). The mean interval from prostaglandin treatment to farrowing was 23.87 h (SD = 10.96). The results of this study suggest that a controlled farrowing system, coupled with good supervision, can improve pig survival. Financial analyses, based on improvements in pig survival resulting from additional labor in the farrowing house, suggested that this method of reducing preweaning mortality is a viable option for improving the profitability of commercial pig farms.
Lactating, primiparous Landrace x Yorkshire sows were used to characterize LH secretion during lactation in sows that experienced an early (less than 9 d; n = 14) or late (greater than 15 d; n = 9) return to estrous postweaning and to evaluate the relationship between LH secretion and blood metabolites. Twenty-three sows were fed one of nine corn-soybean meal diets to achieve a matrix of lysine (15 to 45 g/d) and energy (6.5 to 16.5 Mcal of ME/d) intakes and a range in metabolite concentrations and return-to-estrus intervals. Blood samples for LH analysis were collected every 15 min for 6 h on d 0, 7, 14, 21, and 28 of lactation. Circulating concentrations of glucose, amino acids, insulin, triglycerides, urea N, and nonesterified fatty acids also were measured on d 7 and 21. Mean LH concentrations were .27 and .42 ng/mL at farrowing for sows with an early and late return to estrus, respectively, but decreased (P less than .01) to .12 ng/mL by d 7 in both early and late groups. Mean LH and number of LH peaks per 6 h increased linearly (P less than .01) from d 7 to 28 for early sows. Early sows had a higher LH mean and more LH peaks per 6 h on d 14, 21, and 28 than did late sows (P less than .05). Early sows had higher serum insulin on d 7 (P less than .05) and d 21 (P less than .01) than did late sows. Concentrations of other metabolites did not differ (P less than .10) between early and late sows.(ABSTRACT TRUNCATED AT 250 WORDS)
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