Banca de DEFESA: LUCIANO BRANDALISE

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : LUCIANO BRANDALISE
DATE: 06/08/2020
TIME: 14:00
LOCAL: Web Conferência via Google Meet - meet.google.com/nvh-tmyt-pjn.
TITLE:

Acclimation of Mycoplasma hyopneumoniae-negative replacement gilts naturally exposed to the agent.

KEY WORDS:

qPCR, serology, laryngeal swab, infection dynamics, transmission.

PAGES: 45
BIG AREA: Ciências Agrárias
AREA: Medicina Veterinária
SUMMARY:

Negative Mycoplasma hyopneumoniae (M. hyopneumoniae) replacement gilts provide greater health security to breeding stock. However, in M. hyopneumoniae positive herds, the introduction of gilts presents a higher risk for the vertical transmission at first farrowing, because the transmission of the agent is slow and excretion occurs for an extended period. This study aimed to evaluate the infection dynamics of M. hyopneumoniae in negative replacement gilts, introduced in endemically positive Brazilian farms. For this, ninety-eight gilts, negative for M. hyopneumoniae, were housed in three commercial farms positive for the agent. The animals were arranged in collective pens, which allowed contact with the pens of gilts previously housed on the farm, for a period of 21 days. The infection dynamics was evaluated by detection of M. hyopneumoniae by qPCR and by detection of antibodies by ELISA, from samples of laryngeal swab and blood, respectively. Samples were collected at the time of accommodation (150 days old; do), 165, 180, 210, 240, 270, 300 do and pre-farrowing. It was observed that the transmission occurred quickly in farms A and B, being necessary 25,2 and 23,9 days for 95% of the gilts to be positive in the qPCR. There was no influence on the number of seeders at the time of exposure, but their absence (farm C) extended the transmission period to 69,4 days. Were necessary an average of 162.2 days after the first detection by qPCR so that 85% of the females stop excreting the agent. . There was no significant effect of the farm (p> 0.05) on the infection dynamics, showing an intrinsic characteristic of the agent. The serology results were similar to the herd infection curve, however, as expected, the detection of antibodies occurred after the detection of the agent. At the time of pre-farrowing, 100% of the seroconverted gilts and 36.7% of the gilts remained positive in the qPCR. For evaluation of possible sow-piglet transmission, near weaning nasal swab were collected 75 piglets from 15 litters from negative sows and 75 piglets from 15 litters from positive sows in the qPCR in the pre-farrowing. Only 1.33% of the piglets were positive at weaning, being offspring of females positive in qPCR in pre-weaning and at weaning, both from the same farm. However, it was not possible to detect significant differences (p> 0.05) for this variable. In the conditions of this study, acclimatization by natural exposure to M. hyopneumoniae proved to be efficient, and that possibly other factors (bacterial load, strain-specific immunity, strain virulence, etc ...) may limit the transmission of the female agent to her litter and thus mitigate the onset of the disease in the field.

BANKING MEMBERS:
Externo à Instituição - DAVID EMILIO SANTOS NEVES DE BARCELLOS
Presidente - 1756086 - DIOGENES DEZEN
Interna - 2277465 - FABIANA MOREIRA