SILVA, N. S.; http://lattes.cnpq.br/2746571612038747; SILVA, Natanael de Souza.
Résumé:
Contagious agalactia has a worldwide distribution, with Mycoplasma agalactiae as the
main etiological agent, affecting mainly goats due to the use of this species for dairy
production. The characteristic symptomatological triad of the disease is the development of
agalactia, arthritis and conjunctivitis. The objective of this work was to carry out a systematic
review with meta-analysis on contagious agalactia in small ruminants, to identify the
etiological causes of mastitis in dairy goats and to evaluate the influence of infections by
Mycoplasma spp. and by conventional bacteria causing subclinical mastitis on the quality of
goat milk. The first chapter consists of a systematic review with meta-analysis. The study was
conducted based on the methodological recommendations of PRISMA: the preferred
reporting items for systematic reviews and meta-analyses. A combined prevalence of 10.46%
was observed, with high heterogeneity for the goat and sheep groups, demonstrating the need
for epidemiologically based research to avoid heterogeneous results. The second chapter
aimed to carry out an etiological study for contagious agalactia in dairy goat herds in semiarid
conditions in the states of Paraíba and Pernambuco, Northeast region of Brazil. A total of
207 lactating goats were used, totaling 414 milk samples from 30 asymptomatic herds and 90
samples from three herds with clinical cases of the disease. Positive cultures were subjected to
PCR with specific primers for M. Agalactiae (Ma), M. mycoides Cluster (Mmcluster) and M.
Putrefaciens (Mp). Of the analyzed samples, 34.54% (143/414) showed bacteriological
growth, of which 59.44% (85/143) were positive for Ma, Mmcluster and Mp were not
detected. To carry out the third chapter, the 30 herds described above were used to carry out
the second chapter. The aim was to evaluate the impact of mycoplasmosis and conventional
bacteria causing subclinical mastitis on goat milk quality parameters. Coinfection by
Mycoplasma spp. and conventional bacteria subclinical mastitis was observed in dairy goats
in the Northeast region of Brazil. Subclinical mastitis directly influenced somatic cell counts,
representing a valuable tool for monitoring goat udder infections. On the other hand,
infections by Mycoplasma spp. However, the synergism between conventional agents of
subclinical mastitis and Mycoplasma spp. cause a decrease in the percentages of protein, total
solids, defatting dry extract and casein, demonstrating a greater economic impact on mixed
infections caused by these agents.
