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Biomedical subjects

A D Leman

Publications and source records attributed to A D Leman.

At least 19 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

Factors influencing litter size in swine: parity-one females.

The influence of age at conception, number of matings per conception, season of conception, and breed of female on parity-1 litter size was investigated in 4,944 females from 5 commercial swine herds located in North America. The influence of age at conception on reproductive performance of females in subsequent parities also was investigated. As the age at conception increased from 180 to 245 days, litter size increased 0.017 and 0.012 pig per day, respectively, (P less than 0.05) in 2 of the 3 herds that recorded such data. Age at conception did not influence litter size when conception occurred after 245 days of age. Longevity (parity achieved before death or culling) of females was not influenced by age at first conception. Gilts that conceived before 220 days of age had significantly shorter weaning-to-conception intervals in one herd and shorter farrowing-to-conception intervals in another herd throughout subsequent parities. In 1 of 3 herds that recorded such data, live and total litter size increased from 9.46 to 10.46 and 10.16 to 11.50, respectively (P less than 0.05), as number of matings increased from 1 to 3 per conception. No significant influence of number of matings per conception was observed in the other 2 herds. The effect of season of conception was variable among herds. In 2 herds, there was no significant effect of season of conception on subsequent litter size.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
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

Factors that influence litter size in swine: parity 3 through 7 females.

The influence of 7 factors on litter size for the combined parities 3 through 7 (age at conception of the first litter, parity-1 litter size, duration of lactation in the preceding parity, weaning-to-conception interval in the preceding parity, farrowing-to-conception interval in the preceding parity, number of matings per conception, and month of conception) was investigated in 11,929 litters from 5 commercial herds. Age at conception of the first litter did not influence litter size in these parities in any herd. In the 4 herds that kept such data, duration of lactation negatively influenced the weaning-to-conception interval, and duration of lactation and weaning-to-conception interval positively influenced the litter size in the next parity. Because the effects of duration of lactation and weaning-to-conception interval could not be investigated separately, their effects on litter size were simultaneously investigated, using the farrowing-to-conception interval for these combined parities. In all herds except one, the increase in live litter size was between 0.02 and 0.09 pig for each day increase in the preceding farrowing-to-conception interval less than 36 days (P less than 0.05). Duration of lactation within this farrowing-to-conception interval similarly influenced litter size. Litter size in litters of any herd was not affected by a preceding farrowing-to-conception interval greater than 35 days. In all herds except one, mean litter size of females with a farrowing-to-conception interval greater than 35 days was 0.26 to 0.96 pig greater (P less than 0.1) than for females with a farrowing-to-conception interval greater than 36 days. In 1 of 3 herds that kept such data, 2 matings per conception resulted in a larger mean live litter size than 1 or 3 matings (P less than 0.05). When these females were grouped on the basis of their conception during one of the 3-month seasonal periods, no influence of season on litter size was found. The effect of parity-1 litter size on litter size of subsequent parities 3 through 7 was significant. The regression coefficient ranged from 0.11 to 0.22 (P less than 0.01) in the farrowing-to-conception interval less than 36 days in all herds. In females with a farrowing-to-conception interval greater than 35 days, this association was significant only in one herd.(ABSTRACT TRUNCATED AT 400 WORDS)

Age Factors↗
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↗
PubMed1987

Culling patterns in selected Minnesota swine breeding herds.

This investigation was conducted to study culling patterns in swine breeding herds. Data were obtained from 89 Minnesota swine breeding herds and included 5918 sows and 1324 gilts for a total of 7242 culled femaled. Each producer was involved for 12 consecutive months. They were asked to record every female that was removed from the herd, the reason for its culling and its parity. The annual culling rate for the sample averaged 50%, but varied considerably between herds ranging from 15% to 85%. Culled females had produced an average of 3.77 litters. Half of the females culled did not produce more than three litters. Reproductive failure accounted for 32% of all removals. The average parity of the females culled in that category was only 2.37: almost 33% were gilts. Failure to conceive represented 75% of all females culled for reproductive failure. Proportionally, culling as a result of anestrus was higher in gilts. It accounted for 33% of all gilts culled for reproductive failure which was twice as much as for sows. Inadequate performance accounted for 17% of all removals. These sows had produced an average of 5.11 litters. These results indicated that few animals were culled on the basis of first litter performance. Old age comprised 14% of all removals and the average parity at culling for this category was 7.11. Death accounted for 12% and the average parity for these females was 3.40. Locomotor problems and peripartum problems were the cause of 28% and 23% of all deaths, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1987

Histochemical morphologic features of growth cartilages in long bones of pigs of various ages.

Growth cartilages were obtained from humeri, femora, and ulnae of 31 pigs between 1 and 169 days old. On the basis of stain uptake and distribution, distinct layers were identified in articular-epiphyseal cartilage complexes and growth plates. The laminated appearance was dependent on stain uptake by territorial and interterritorial matrices and was more distinct in pigs greater than 15 days old. There was morphologic heterogeneity, which probably represented a functional heterogeneity, among chondrocytes in all layers and zones of both types of growth cartilage. The laminar appearance of growth cartilages and the distribution of different types of cells were similar for all pigs in each age category and for all sites.

Aging↗
PubMed1985

Dyschondroplasias of growth cartilages (osteochondrosis) in crossbred commercial pigs at one and 15 days of age: radiological, angiomicrographical and histological findings.

The age of onset and morphology of the earliest lesions of dyschondroplasias in pigs have not been established. Bones and growth cartilages from pigs were examined for the presence of lesions using radiological, angiomicrographical and histological techniques. Lesions were in 10 of 11 pigs at 15 days of age and 12 of 21 pigs at one day of age, indicating that the condition was congenital. The simplest and apparently earliest lesion was an area of persistent hypertrophied chondrocytes and matrix which extended from the articular-epiphyseal complex or physis into the epiphysis or metaphysis, respectively. Since the prevalence of lesions was high it was considered that the dyschondroplasia may be part of the usual growth pattern of cartilages in contemporary pigs.

Animals↗
PubMed1985

Angiomicrographic investigation of the vessels associated with physes in young pigs.

There is little information available relating to the vasculature of physes of pigs, hence the object of the present study was to establish the distribution of blood vessels in normal physes of pigs at one and 15 days old. By the use of an angiomicrographic technique it was possible to demonstrate that vessels were in two main categories; first, those which entered the physis from the epiphysis and terminated, or branched and then terminated half to two thirds of the distance into the depth of the physis; second, vessels which crossed the full depth of the physis. Since vessels that cross the physis from epiphysis to metaphysis were a frequent feature of normal physes they do not seem to be a congenital defect which predisposes to the development of dyschondroplasias in young pigs.

Aging↗
PubMed1984

Pneumonia and atrophic rhinitis in pigs from a test station--a follow-up study.

Pneumonia and atrophic rhinitis were studied for the second consecutive year in pigs at the same test station. Pneumonia was found to reduce mean daily gain by 3.3% for every 10% of the pig's lungs that had lesions. Atrophic rhinitis did not affect mean daily gain. There was no association between the development of atrophic rhinitis and the development of pneumonia. Pigs that were vaccinated with a Bordetella bronchiseptica bacterin did not have turbinate atrophy scores or mean daily gains different from those in pigs that were not vaccinated. Yorkshire and Hampshire pigs had higher prevalences and severity of pneumonia and atrophic rhinitis, compared with pigs of other breeds.

Animals↗
PubMed1984

Swine diseases transmissible with artificial insemination.

The transport of fresh and frozen semen to be used for artificial insemination creates a mode of disease transmission between farms. Normally, semen contains a number of nonpathogenic bacterial contaminants; however, excessive bacterial contamination can result in infertile matings. Contamination with a known pathogen, eg, Brucella suis, could initiate a serious outbreak of disease in a recipient herd. Methods to minimize bacterial contamination of semen include sanitary collecting and processing of semen, isolation of boards from certain pathogens, and the addition of appropriate broad spectrum or combination antibiotics to the semen. Mycoplasmas also have been isolated from semen, although transmission by this route is unlikely. The addition of an appropriate antimycoplasmal antibiotic to semen may be warranted in some situations. Numerous viruses have been detected in semen. Their exclusion from semen is especially critical because of their ability to survive in frozen semen. These viruses include pseudorabies virus, porcine parvovirus, enterovirus, adenovirus, vesicular disease virus, and African swine fever virus. The likelihood of disease transmission is greater with the introduction of a boar into a herd than through the use of fresh or frozen semen. We believe that artificial insemination allows for the introduction of new genetics into a breeding program, with minimal risk of disease transmission.

Animals↗
PubMed1984

Isolation of toxigenic strains of Pasteurella multocida from lungs of pneumonic swine.

Lungs from 113 pneumonic pigs were examined for Pasteurella multocida. The lungs were smeared directly onto blood agar and homogenized in brain-heart infusion broth and then inoculated intraperitoneally in mice. Pasteurella multocida isolates were typed for serotypes A (by hyaluronidase inhibition of capsule) and D (by acriflavine autoagglutination). Strains were tested for toxin production by intradermal injection of 0.2 ml of filtered 24-hour culture supernatants into guinea pigs. Most lungs (70.8%) yielded isolations. Most isolants (87.5%) were type A and 12.5% were type D. Of the type D strains, 80% were toxigenic. Of the type A isolants, 18.2% were toxigenic.

Animals↗
PubMed1984

Antibody responses of guinea-pigs, rabbits and pigs to inactivated porcine parvovirus vaccines.

Antibody responses were compared in guinea-pigs, rabbits and pigs following vaccination with inactivated porcine parvovirus (PPV) vaccines. Mean PPV hemagglutination inhibition (HI) antibody titers of 52, 56 and 36 at 1 week after first vaccination and 896, 640 and 512 at 2 weeks after second vaccination were detected in guinea-pigs, rabbits and pigs, respectively. PPV vaccines prepared with greater concentrations of virus, as determined by hemagglutination (HA) units, and of aluminum hydroxide gel adjuvant, induced higher HI antibody titers in guinea-pigs. Optimal concentrations for inducing consistently high antibody titers consisted of vaccine virus with a HA titer of 256/0.1 ml and gel adjuvant at a final concentration of 50%. A second vaccination at 4 weeks compared to 2 or 3 weeks after first vaccination resulted in higher mean HI titers. These data provide preliminary information on the use of guinea-pigs or rabbits as laboratory animal models for testing the potency of PPV vaccines.

Animals↗
PubMed1984

Radial immunodiffusion enzyme assay for detection of antibodies to pseudorabies virus in swine serum.

A radial immunodiffusion enzyme assay for the detection and quantitation of antibodies to pseudorabies virus in swine sera was developed and the methods were standardized. The assay combined the principle of radial immunodiffusion with enzyme-linked immunosorbent assay. Quantitation of pseudorabies virus antibody titers was determined by measuring the diameter of a colored circular zone after overnight incubation of antibody with antigen. The specificity and sensitivity of the radial immunodiffusion enzyme assay were compared with that of the standard virus-neutralization test, and the results were determined to be correlated highly (r = 0.694, P less than 0.0001). The assay also appeared to be highly reproducible and simple to perform.

Animals↗
PubMed1983

Factors affecting mortality in finishing pigs.

Two groups of finishing pigs at a test station were studied to test the effect of initial weight, weight change in the 1st week, age, breed, and distance the pig was transported on mortality. Total mortality was 5.3% in 1 group and 6.3% in the other group. Specific causes of death were pneumonia (24.7%), gastric ulceration (14.0%), enteritis (6.4%), trauma (4.3%), gastrointestinal displacement (4.3%), rectal stricture (3.2%), porcine stress syndrome (3.2%), and brain abscess (2.2%). Other categories for cause of death were miscellaneous (6.5%), and undiagnosed (31.2%). More pigs died in the last 6 weeks of the 18-week finishing period than in the 1st 6 weeks (P less than 0.05). Death rates were not significantly different between pigs that lost weight and pigs that maintained or gained weight during the 1st week after arrival at the test station. The mean transportation distance to the test station was not significantly different between pigs that died and pigs that survived. Transportation distance was not correlated with mean daily gain. The death rate was significantly (P less than 0.03) higher for Yorkshire pigs than for crossbred, Poland China, Hampshire, and Duroc pigs, and it was significantly (P less than 0.01) higher for Berkshire, Spot, and Chester White pigs than for Hampshire and Duroc pigs.

Animals↗