Association of herd-level risk factors and incidence rate of clinical mastitis in 20 Brazilian dairy herds

Autor(es)

Tomazi, Tiago ^[1] ; Ferreira, Gabriel C. ^[1] ; Orsi, Alessandra M. ^[1] ; Goncalves, Juliano L. ^[1] ; Ospina, Paula A. ^[2] ; Nydam, Daryl V. ^[2] ; Moroni, Paolo ^{[2, 3]} ; dos Santos, Marcos V. ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Sch Vet Med & Anim Sci, Dept Anim Nutr & Prod, Pirassununga - Brazil

^[2] Cornell Univ, Coll Vet Med, Dept Populat Med & Diagnost Sci, Ithaca, NY 14853 - USA

^[3] Univ Milan, Dipartimento Med Vet, Milan - Italy

• Tipo de documento: Artigo Científico
• Fonte: PREVENTIVE VETERINARY MEDICINE; v. 161, p. 9-18, DEC 1 2018.
• Citações Web of Science: 0

Resumo

The objectives of this study were to characterize the pathogen frequency and severity of clinical mastitis (CM) in 20 dairy herds of southeastern Brazil; and to determine the incidence rate of clinical mastitis (IRCM; overall and based on specific-pathogen groups) based on quarter time at risk and its association with risk factors at the herd level. Data were recorded in each herd for a period of 8 to 15 months. The association between herd-level risk factors and IRCM were determined by two groups of mixed regression models: one based on the overall IRCM, and five based on the following specific-pathogen groups: contagious, other Gram-positive, Gram-negative, other, and negative culture. The following herd-level risk factors were evaluated: herd size, housing system, average daily milk yield per cow, bulk milk somatic cell count (BMSCC), and bulk milk total bacterial count (BMTBC). A total of 5957 quarter-cases of CM were recorded from 2637 cows, but only 4212 cases had milk samples collected for culture. The most frequently isolated pathogens were Fscherichia coli (6.6% of total cultures), Streptococcus uberis (6.1%), and Streptococcus agalactiae (5.9%). The majority of CM cases were mild (60.3%), while 34.1% were moderate and 5.6% severe. The frequency of severe CM cases was lower for those with a Gram-positive result (4.6%) compared to a Gram-negative result (11.4%). Overall, monthly mean IRCM was 9.7 cases per 10,000 quarter-days at risk (QDAR). Herds with a geometric mean BMSCC >= 601 x 10(3) cell/ mL had higher overall IRCM (16/10,000 QDAR) than those with BMSCC <= 600 x 10(3) cell/mL (<= 7.7/10,000 QDAR). When the specific-pathogen groups were evaluated, for contagious pathogens, variables housing (free stalls or compost-bedded pack barns), BMSCC (>= 601 x 10(3) cells/mL), and average daily milk yield per cow (21 and 25 Kg/d) presented the highest IRCM. Furthermore, in Gram-negative group, herds with BMTBC >= 31 x 10(3) cfu/mL had higher IRCM compared with herds with BMTBC <= 30 x 10(3) cfu/mL. Although environmental pathogens were the most common cause of CM in this study, contagious pathogens (e.g., Strep. agalactiae and Staph. aureus) are still a concern in dairy herds of Brazil. Additionally, as there were some herd-level risk factors associated with the IRCM, there may be opportunity for management strategies aiming to improve the control of CM in dairy herds. (AU)

• Processo FAPESP: 14/17411-6 - Impacto econômico e perfil de agentes etiológicos da mastite bovina
• Beneficiário: Marcos Veiga dos Santos
• Modalidade de apoio: Auxílio à Pesquisa - Regular