Adil Knackfuss Vaz

Imunidade inata da glândula mamária bovina: resposta à infecção

The immunity in the mammary gland can be, as in other systems, classified in innate or adaptive immunity. The innate immunity is the predominant defense during the initial periods of infection. The non-specifics answers are present or are quickly activated in the infections site by numerous stimulations, and these answers are not enhanced by repeated exposure to the same agent. The first obstacle to be faced by the agent is the barrier represented by the teat sphincter and the keratin plug. When the pathogenic agent crosses the teat canal and reaches the teat cistern, starts to act the humoral factors and the phagocytic cells starts do act. Among the humoral mediators there are the lactoperoxidase, complement, cytokines, lactoferrin, lysozyme and NAGase. The non-specific cellular defenses are represented by neutrophils, macrophages and natural killer cells. If these mechanisms have been functioning adequately, the majority of pathogens will be eliminated in a short time, before the specific immune system be activated. The fast elimination of the microorganisms will not allow these alterations in the amount or quality of produced milk. The best understanding of the defense mechanisms of the mammary gland and its alterations during the critical periods of infection, is an useful tool in devising and developing methods to control the mastitis, the major illness of dairy ruminants. This paper overviewed the most important aspects of the innate immunity of bovine mammary gland.

Brucella abortus RB51 in milk of vaccinated adult cattle

The aim of this study was to evaluate the shedding of Brucella abortus in the milk of cows vaccinated with a full dose of RB51 during lactation. Eighteen cows, nine previously vaccinated with S19 as calves and nine non-vaccinated, were immunized subcutaneously with 1.3×10(10)CFU of B. abortus RB51, 30-60days after parturition. Milk samples from all animals were collected daily until day 7, and at weekly interval for the next 9 weeks after vaccination. To evaluate the shedding of B. abortus, milk samples were submitted for culture and PCR. No B. abortus was isolated from any sample tested. Only one sample, collected on first day after vaccination from a cow previously vaccinated, was faintly positive in the PCR. In conclusion, the public health hazard associated with milk consumption from cows vaccinated with RB51 in post-partum is very low, despite vaccination with the full dose and regardless of previous S19 vaccination.

A SURVEY OF SHEEP MASTITIS IN SOUTHERN BRAZIL

SUMMARY Ovine mastitis causes varying economic fosses in all countries where sheep are kept. A survey of 3128 breeding ewes in 22 farms in two areas with different management practices in Southern Brazil showed that the average prevalence of subclinical and chronic mastitis was 14.1% of ewes with at least one affected gland. From those, 4.49% were also bacteriologically positive. The prevalence in individual farms varied from 0 to 37% of ewes with clinical abnormalities of the udder. The overall prevalence was greater in Area II, where meat breeds predominate and animals are housed at night. It is concluded that subclinical and chronic mastitis is uniikely to be an economic problem in Area I, where wool production is the objective of the sheep industry. However, in individual farms with high prevalence of the disease lamb survival and development may be affected. In Area II, mastitis is more likely to be a problem because of the higher prevalence found in that area.