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Biomedical subjects

A D Leman

Publications and source records attributed to A D Leman.

At least 37 records · Page 2Linked to original sources
PubMed1983

Farm studies of porcine parvovirus infection.

Epizootics of reproductive failure associated with porcine parvovirus infection were investigated on 38 farms. Mummification was common to all epizootics. The mean number of mummified fetuses per affected litter was 3.1. Mean number of pigs born alive for gilts and sows farrowing litters with mummified fetuses was 5.0, but for sows without mummified litters on the same farms it was 9.0. Mummified fetuses were observed in aborted litters on 8 (21.1%) farms. Gilts and sows that appeared pregnant but "lost" their swollen abdomens and failed to farrow were observed on 12 (39.5%) farms. Delayed return to estrus was evident on only 3 (7.9%) farms with a continuous farrowing program. On 21 farms with a batch farrowing program, only 2 (10%) epizootics involved more than 1 batch. Up to 100% of the pregnant swine in the group farrowing together produced mummified pigs, but less than 20% of the breeding herd was affected in 26 (68.4%) cases. The prevalence of disease was not related to herd size, housing, or farrowing management.

Animals↗
PubMed1982

Role of the rat in the transmission of porcine parvovirus.

Rats experimentally inoculated with porcine parvovirus (PPV) shed virus in excreta from 3 to 21 days. Rats inoculated subcutaneously with PPV responded serologically with hemagglutination-inhibition titers (512-1,024). The PPV antigen was readily detected in lung and spleen 2 and 3 days after rats were inoculated and in liver and intestine, 4 days. The rats remained clinically healthy. Rats given PPV orally or in drinking water either with PPV-infected cell culture fluid or swine fetal homogenate failed to respond serologically to PPV, the exception being 2 of 4 rats exposed to swine fetal homogenate over a 5-day span. Pigs exposed to PPV-contaminated rat excreta, either by direct oral dosing or by contaminating the feed, failed to seroconvert. Pigs given (IM) PPV which had been isolated on cell culture from rat excreta did seroconvert. Results of these experiments indicated that rats became infected with PPV, but did so after systemic challenge exposure or prolonged oral exposure to highly infective swine fetal homogenate. Insufficient virus was shed by rats to cause susceptible pigs to seroconvert upon oral feeding--thus indicating that a minimal dose is necessary to ensure oral challenge. In a preliminary experiment, seronegative pigs given different doses of PPV orally showed a gradient level of serologic response and different rates of shedding.

Animals↗
PubMed1982

Effect of porcine parvovirus serostatus on the reproductive performance of mated gilts in an infected herd.

Gifts from 2 commercial swine operations (farm A and farm B) that were bred each week were tested for porcine parvovirus antibody. On farm A, 21.9% (weekly, 2% to 35%) of the 657 gilts tested over a 16-week period were seronegative within 1 week of mating. On farm B, 17.7% (weekly, o to 40%) of the 164 gilts tested over a 10 week period were seronegative within 1 week of mating. Eighty-one gilts from farm A which were seronegative at time of mating were retested at the end of the gestation. Of the 81 gilts, 4 1 had developed antibody titers. The litter size decreased by 1.3 live pigs/litter. The percentage of small litters (less than or equal to 6 born alive) in the group that seroconverted was 36.6% compared with 10% in the gilts that remained seronegative throughout gestation.

Animals↗
PubMed1981

The seasonal breeding pattern of sows in seven confinement herds.

The breeding herd records from 7 confinement herds were analyzed to determine the association of season with the frequency of estrus within 1 week after weaning and the farrowing rate following mating during this estrus. All herds utilized the cooling of sows during lactation and water fogging during the postweaning, breeding and early gestation periods. During July, August and September, the frequency of estrus within 7 days after weaning was lower (P < 0.05) than the frequency of estrus during October, November and December. The farrowing rate for matings during September and October was lower (P < 0.05) than the farrowing rate for sows mated from February through May. These data suggest that reduced postweaning estrous activity and fertility may occur in confinement herds, despite the use of cooling systems used to minimize heat stress of sows during hot weather.

Journal Article↗
PubMed1981

Survey of porcine parvovirus infection in swine fetuses and their dams at a Minnesota abattoir.

Reproductive tracts were recovered from 209 sow and 32 gilt carcasses at slaughter; animals had been pregnant not less than 27 days. Of 241 litters examined, 28 (11.6%) contained one or more porcine parvovirus (PPV)-infected fetuses, as determined by immunofluorescent microscopy. The frequencies in sow and gilt litters were 12.0% and 9.4%, respectively. The PPV antigen was detected in 219 of 334 (65.6%) dead or mummified fetuses and in 12 of 2,172 (0.5%) live fetuses examined. The 18 litters which contained only dead or mummified fetuses were infected with PPV. As the percentage of litter mummification increased, the likelihood of finding PPV increased. The PPV antibody was detected in ovarian follicular fluids of 94.3% of the sows and 78.1% of the gilts. These findings indicate that PPV is highly associated with fetal mummification and that some pregnant gilts and sows are susceptible to infection.

Abattoirs↗
PubMed1980

Seasonal influence on the fertility of sows and gilts.

Seasonal fluctuations in the farrowing rates (FR( of sows and gilts were determined by analysis of breeding records from 11 herds, covering a total of 26 herd-years of data. Of 22,997 sow and gilt matings, 72.7% resulted in farrowing. For matings during July, August, and September, 60.8% of females farrowed, compared with 76.9% for matings during the remainder of the year. The FR was higher in multiparous sows than in primiparous sows and was lowest in nulliparous gilts. The FR was 65.5% for gilts bred in confinement and for gilts maintained outside. The seasonal fluctuation in FR was similar for confinement and outside-housed gilts. Water sprinkling or evaporative cooling methods did not prevent seasonal fluctuations in the FR of sows or gilts. For sows confined to crates after breeding, the FR was 13.8% higher than for sows in group-housing systems, but the seasonal fluctuation in FR was not substantially altered. It was concluded that the FR of female swine is markedly influenced by season of the year and by parity. The seasonal fluctuations in FR occurred in group- and individually housed swine and in confinement and outside-bred gilts. Water sprinkling or evaporative cooling systems, as used in the herds investigated, appeared to be of questionable value in preventing infertility during the warm months.

Animals↗
PubMed1980

Seasonal influence on estrous activity in sows and gilts.

Seasonal fluctuations in the estrous activity of sows after weaning and of sows and gilts after mating were determined by analysis of breeding records from eight swine herds covering a total of 19 herd-years of data. Of 11,461 sows, 78.4% were in estrus within 7 days after weaning. From July through September, 68.6% of sows returned to estrus within 7 days after weaning, compared with 82.0% during the remaining 9 months of the year. An increase in postweaning anestrus of more than 30 days' duration also occurred during summer months. Seasonal fluctuations in the frequency of postweaning estrus were similar for sows moved from farrowing facilities to environments with or without specialized temperature control features. For sows confined to crates after weaning, the rate of postweaning return to estrus was 10.4% greater than for sows in group-housing systems, but the seasonal pattern in postweaning return to estrus was not altered. Postweaning estrous failure was more obvious in primiparous sows than in multiparous sows, especially during summer and fall. The frequency of delayed return to estrus after infertile mating was 63.7% for matings during the period July through September and 29.7% for the period January through March. It was concluded that postweaning and postservice estrous activities in swine are influenced by season of the year and by parity. Group housing of sows or individual crating of sows, and water sprinkling or evaporative cooling systems in the postweaning breeding area, as used in the herds investigated, appear to be of questionable value in preventing estrous failure during summer and fall months.

Animals↗
PubMed1980

Semen changes in boars after experimental infection with pseudorabies virus.

Two groups of adult boars were inoculated with a field strain of pseudorabies virus (PRV) by intranasal droplet; one group was given 5 x 10(5) median tissue culture infective doses (TCID50), and the other, 5 x 10(6) TCID50. (A third group was maintained as controls.) Ejaculates were examined twice a week for volume, sperm numbers, sperm morphology, and presence of PRV. Severe clinical disease with fever followed administration of the larger virus dose. Death (one boar), testicular degeneration, and transient elevation in spermatozoa with proximal cytoplasmic droplets were seen in different members of this group. The smaller dose resulted in seroconversion, but did not produce signs of disease. In this group, volume, sperm numbers, and sperm morphology did not decline when compared with base-line values or data of control animals. The virus was not isolated from semen. Effects of PRV infection on semen quality in boars seem to be related to the associated clinical signs of systemic disease.

Animals↗
PubMed1979

Use of PMSG in the prevention of seasonal post-weaning anestrus in sows.

PMSG (500 I.U.; administered I.M.) prevented post-weaning anestrus when given to sows weaned during the months of August, September and October compared to untreated controls during the same months. During winter and spring months, there was no difference in the post-weaning return to estrous rate for treated and control sows. Control sows had a greater degree of estrous synchrony following weaning during winter and spring months compared to summer months. PMSG-treated sows were in estrus earlier (frequently Day 3) than controls. Results indicate that PMSG, given at weaning, is effective in preventing summer-early fall post-weaning anestrus.

Journal Article↗
PubMed1976

Boar management.

Many boar problems result from an insufficient number of boars in relation to the number of sows in the herd, sexually immature boars, inadequately preconditioned or improperly managed boars. The following factors which determine optimum boar efficiency are discussed: (a) sexual development and mating behaviour, (b) selection, (c) preconditioning, (d) mating systems, (e) examination and culling.

Animals↗
PubMed1975

Reproductive failure in swine associated with maternal seroconversion for porcine parvovirus.

Reproductive failure occurred in a swine herd in which the epizootiology of enteroviruses and the porcine parvovirus were being studied. Three virgin boars that were seropositive for the parvovirus were mated to seronegative, previously unmated gilts. The 11 gilts that farrowed had small litters, with high perinatal mortality. The remaining 12 gilts were marketed because of infertility, and the reproductive tracts were examined. Pathologic findings included early embryonal death attributed to viral infection. After the reproductive failure, all gifts and boars were seropositive for the parvovirus, suggesting that the reproductive failure was associated with a parvovirus infection.

Animals↗
PubMed1975

Effects of parasympathominetics on porcine stillbirth.

To study the effect of 2 parasympathomimetic drugs in reduction of incidence of stillborn pigs, 84 sows and gilts were randomly allotted to 3 treatment groups. Single 1-ml injections of isotonic saline solution, carbachol (2 mg/ml), or neostigmine bromide (5 mg/ml) were subcutaneously administered to pigs of groups A, B, and C, respectively. Injections were given midway through parturition in an attempt to hasten the delivery of the last pigs in the litter, where the corresponding incidence of stillbirth is greatest. The mean time of injection was after the birth of 3.5 pigs. Total stillbirths/litter for carbachol-treated (0.23) and neostigmine-treated (0.21) pies were significantly different (P greater than 0.0001) from those for control pigs (0.88). Before injection, stillbirths/litter for control pigs (0.23) were not significantly different from those for carbachol-treated (0.18) or neostigmine-treated (0.12) pigs. After treatment, stillbirths/litter for carbachol-treated (0.06) and neostigmine-treated (0.09) pigs were both significantly different (P greater than 0.0001) from those for saline solution-treated control pigs (0.65). When injected midway through parturition, carbachol and neostigmine reduced stillbirth rate by reducing stillbirths which occur late in farrowing.

Animals↗