Biography:

In the past A.E. Wrathall has collaborated on articles with A.E. WRATHALL and S.C. Hathaway. One of their most recent publications is 27 - INVESTIGATION AND CONTROL OF REPRODUCTIVE DISORDERS IN THE BREEDING HERD. Which was published in journal .

More information about A.E. Wrathall research including statistics on their citations can be found on their Copernicus Academic profile page.

A.E. Wrathall's Articles: (7)

Experimental Infection of Pregnant Gilts with Leptospires Isolated from British Wildlife. I. Serological Response to Infection

SUMMARYFour groups of pregnant gilts were inoculated on day 70 of gestation with leptospires isolated from wildlife in England. The infecting serovars were muenchen, bratislava, copenhageni and a leptospire belonging to the Pomona serogroup. The serological response until day 114 of gestation was monitored in the microscopic agglutination test using a battery of 16 antigens from 12 serogroups.Homologous titres to the infecting serovar predominated in all groups of pigs. There was a rapid decline from peak titres after day 33, and this has important implications in the diagnosis of leptospiral abortion and neonatal death of piglets. A lower plateau of titres was seen in the more chronic stages of infection.Cross-reactions to heterologous antigens were a common finding and were variable in individual animals within each group. Paradoxical reactions to bratislava were also seen at some sampling times in pigs infected with muenchen and copenhageni. The implications of these serological findings are discussed with respect to serological surveys in England.This study demonstrated that experimental infection with the serovars present in a particular geographical region can provide information to improve serological diagnosis in field investigations and allows provisional identification of infecting serovars.

Effect of Porcine Parvovirus on Development of Fertilized Pig Eggs in Vitro

SUMMARYFertilized eggs, collected from four oestrus-synchronized gilts 32 h after presumed ovulation, were cultured for five days in a synthetic culture medium with or without porcine parvovirus (PPV). The proportion of virus-exposed eggs which developed to the blastocyst stage was significantly lower than the proportion of controls (53% v. 80%).Examination by the direct fluorescent antibody technique at the end of culture showed that viral antigen had adhered to the outer surface of the zona pellucida but the virus did not seem to have penetrated into the blastocyst itself. It is concluded that although PPV may not seriously interfere with development of the intact fertilized pig egg up to the early blastocyst stage in vitro, the presence of the virus on the zona pellucida could pose a threat to development after hatching occurs.

Effect of Transferring Parvovirus-Infected Fertilized Pig Eggs into Seronegative Gilts

SUMMARYFertilized eggs were collected from four oestrus-synchronized donor gilts 32 h after presumed ovulation and were cultured for 21 h in a synthetic culture medium containing porcine parvovirus (PPV). They were then washed and transferred into four seronegative recipient gilts. Eight days later the recipient gilts were killed. Blastocysts were recovered from three of the four recipients but many of them were dead, and those which were still alive were smaller than normal. Examination of the blastocysts by the direct fluorescent antibody technique (FAT) revealed a small number of infected cells, but retardation and death of the blastocysts could not with confidence be ascribed to this infection. All four recipient gilts seroconverted following insertion of the infected eggs, and virus was detected by FAT in their uterine lymph nodes at slaughter. Histopathological changes were seen in their reproductive tracts; in particular there were inflammatory foci in the ovaries, and a marked degeneration and exfoliation of the uterine epithelium. Although PPV was not demonstrated in sloughed epithelial debris it is nevertheless considered that the uterine damage was a direct result of PPV infection. It is also probable that retardation and death of the blastocysts was a consequence of this uterine damage rather than the direct effect of virus infection.

Reproductive Disorders in Pigs. I. DiagnosisDésordres reproduisibles chez les porcs. I. DiagnoseFortpflanzungsstörungen bei Schweinen. I. DiagnosisEnfermedades reproductivas de los cerdos. I. Diagnosis

SUMMARYThis paper outlines a framework for investigation of reproductive disorders in the pig breeding herd. Analysis of breeding records is dealt with initially and is followed by discussion of points to be observed when examining the animals and their environment. The paper then deals with basic pathological and epidemiological patterns of failure of the reproductive processes with emphasis on distinguishing between those which primarily involve the sow or boar (maternal or paternal failure) and those which primarily involve the embryos (embryonic failure). The use of some pathological techniques to identify and differentiate these patterns of failure are discussed, including radiographic techniques for study of stillborn, mummified and macerated foetuses. Finally diagnostic tests are considered and a plea is made for care in their selection and interpretation.

The Effect of Feeding Ergot to Gilts during Early PregnancyL’effet de l’administration d’ergot à des truies, pendant les premiers temps de graviditéDie Wirkung mit Ergotverfütterung an jungen Säuen im Beginn der TrächtigkeitEfectos de la alimentación con ergot en cerdas jovenes durante la gestación precoz

SUMMARYRye ergot sclerotia (Claviceps purpurea) containing 0 · 25 per cent ergotamine were fed to a total of 9 gilts at doses of between 5 and 80 g/day for 11-day periods during early pregnancy. The first treatment period extended from Day 8 to 18 covering the preimplantation and implantation stage; the second period lasted from Day 18 to 28 covering the immediate postimplantation stage. Six untreated gilts were used as controls. Results were assessed after slaughter of gilts on Day 30 by detailed quantitative measurements made on the embryos and their organs and on the placentae. The ergot treatments did not interfere with maintenance of pregnancy neither did they have any adverse effects on blastocyst implantation or on organ weights of embryos.

ReviewRisks of transmitting ruminant spongiform encephalopathies (prion diseases) by semen and embryo transfer techniques

AbstractEarly experiments suggested that scrapie transmission via sheep embryos was a possibility, and gave rise to much controversy. However, when account is taken of the complex genetic effects on ovine susceptibility to scrapie, and of the several different scrapie strains with different clinical and pathological effects, the overall conclusion now is that transmission of classical scrapie by embryo transfer is very unlikely if appropriate precautions are taken. Recent embryo transfer studies have confirmed this. Other studies in sheep have shown that from about the middle of pregnancy the placental trophoblast is liable to scrapie infection in genetically susceptible ewes if the fetus is also susceptible. Since the contrary is also true, use of resistant ewes as embryo recipients could add to the safety of the embryo transfer, at least for classical scrapie. There has been little recent research on scrapie transmission via semen in sheep, and, with hindsight, the early studies, though negative, were inadequate. There is scant information on scrapie transfer via goat semen or embryos, although one study did find that bovine spongiform encephalopathy (BSE) was not transmitted via goat embryos. In cattle it has been shown that, if appropriate precautions are taken, the risks of transmitting BSE via semen and in vivo-derived embryos are negligible, and this conclusion has gained worldwide acceptance. Research on TSE transmission via reproductive technologies in deer has not yet been done, but information on the pathogenesis and epidemiology of chronic wasting disease (CWD) of deer, and on transmission risks in other species, provides optimism that transmission of CWD via semen and embryos of deer is unlikely. The presence of TSE infectivity in blood and various other tissues of infected animals, particularly sheep, gives rise to concerns that certain biological products currently used in reproductive technologies, e.g. pituitary gonadotrophins for superovulation, and certain tissue and blood products used in semen and embryo transfer media, could carry TSE infectivity. Instruments such as laparoscopes used for insemination, and for collection and transfer of embryos, especially in small ruminants, are also a concern because effective decontamination can be very difficult.

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