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Biomedical subjects

A D Leman

Publications and source records attributed to A D Leman.

12 recordsLinked to original sources
PubMed1992

Optimizing longevity in sows and boars.

Longevity of sows and boars affects the productivity and economics of the herd. Implement a culling program that is tailored to the specific needs of the producer and the characteristics of the farm. Evaluate the removal policies regularly, estimate the longevity of breeding animals, calculate the nonproductive sow days associated with culling, and determine the major causes of culling and death. Once a longevity problem and its extent have been identified, the underlying problems and predisposing factors can be more easily corrected.

Animal Husbandry↗
PubMed1992

Optimizing farrowing rate and litter size and minimizing nonproductive sow days.

The most universally accepted measure of reproductive performance is PSY. Excellence is achieved by reducing NPD, increasing liveborn litter size, and reducing preweaning mortality. To reduce NPD, farm management should be directed to improve farrowing rate. Matings that occur in late summer usually are less fertile as the result of the pig's normal seasonal variation. Confinement gestation stalls are the best prevention for the reduced farrowing rate caused by season. Liveborn litter size is the result of a mixture of genetic and management variables. F1 females have the highest heterosis. The management variables of age at first mating, wean-to-service interval, skip mating, lactation length, and parity all influence litter size.

Animal Husbandry↗
PubMed1991

Pig weaning weight and changes in hematology and blood chemistry of sows injected with recombinant porcine somatotropin during lactation.

Weaning weight of pigs on d 18 to 21 of age was used to determine the effects of recombinant porcine somatotropin (rpST) on lactational performance of their dams. Crossbred Landrace x Yorkshire sows (n = 180, 202 to 270 kg BW) were assigned to receive daily i.m. injections of either 0, 8, or 16 mg of rpST on lactation d 7 to 20. Initially, injections of 16 mg of rpST/d caused 100% mortality (four sows); thus, a dose of 4 mg of rpST/d replaced 16 mg. Subsequently, 5 of 19 and 1 of 17 sows died in response to daily injections of 8 and 4 mg of rpST, respectively, resulting in termination of the experiment. Before termination, 48 sows (16 from each of the 0-, 4-, and 8-mg treatment groups) completed a lactation of 18 to 21 d in duration. Analysis of these data indicated that daily injection of lactating sows with rpST increased (P less than .05) weaning weight of pigs only if they were from litters that averaged greater than or equal to 2.6 kg/pig on lactation d 7. The BW of sows was decreased by rpST (P = .07). Subsequent experiments revealed 1) that rpST-induced death of lactating sows was caused from hemorrhaging of ulcers that developed at the pars esophagea, 2) that there was vacuolation of the liver and kidney of dead sows, and 3) that daily injection of 16 mg of rpST into nonlactating growing pigs (50 to 100 kg BW) for 28 d did not cause death or any observable illness in spite of 100% mortality of lactating sows after two to nine injections.

Animals↗
PubMed1988

Detection of antibody to encephalomyocarditis virus in mummified or stillborn pigs.

Fetal sera or thoracic fluids of the abnormal fetuses from different swine farms were tested for the presence of antibody to encephalomyocarditis (EMC) virus. Sera of swine fetuses infected experimentally with EMC virus were also tested. High antibody titers ranging 1:128-4096 were detected in both field and experimental samples. Detection of the positive antibody was associated with clinical herd history of increased mummification, stillbirth and neonatal death. The results suggest that EMC virus may be a natural cause of swine reproductive failure and fetal infection can be diagnosed by detecting specific EMC virus antibody in either fetal sera or thoracic fluids.

Animals↗
PubMed1987

Clinical, virologic, and histopathologic observations of induced porcine parvovirus infection in boars.

Twelve 8- to 12-month-old crossbred boars were inoculated with a virulent strain (NADL-8) of porcine parvovirus (PPV). Hemicastrations were performed on 6 boars 3, 7, 10, 14, 21, and 28 days after an IM injection of 10(8) median cell culture infectious dose (CCID50) of PPV (n = 3) or injection of 10(7.4) CCID50 given intratesticularly (IT, n = 3). Noninfected cell culture medium (0.25 ml) was injected into each testicle of a 7th boar (IT inoculated control). Virus or viral antigen was detected in testicular and epididymal tissues up to 14 days after inoculation. Direct immunofluorescence indicated that viral antigen was mainly associated with the vasculature of the interstitium. Microscopic lesions were not evident in the testicles and epididymides of IM inoculated boars. Acute-to-chronic testicular degeneration was evident in the IT inoculated boars, as well as in the IT inoculated control boar. Six boars were inoculated IM or orally/nasally with 10(7.9) CCID50 of PPV. Semen was collected twice weekly for 8 weeks after inoculation. Virus was not detected in any ejaculates. Semen also was collected from 4 boars for 5 weeks before inoculation, and preinoculation and post-inoculation semen quality was compared. Pronounced changes in sperm output, ejaculate volume, motility, or morphologic defects were not observed. The reproductive consequences of experimental PPV infection in boars were minimal because reproductive function was unaffected and venereal transmission of PPV was not detected.

Animals↗
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↗