Prevalencia, incidencia y factores de riesgo de mastitis subclínica en lecherías especializadas en Colombia

espanolIntroduccion. La mastitis subclinica (MSC) es una de las principales enfermedades en bovinos; estudiar su epidemiologia es fundamental para implementar programas de salud. Objetivo. Determinar la prevalencia, la incidencia y factores asociados a la mastitis subclinica en lecherias especializadas en Cundinamarca, Colombia. Materiales y Metodos. Se realizo un estudio observacional-analitico, de cohorte-prospectivo. Quince fincas se visitaron tres veces cada 56 dias (septiembre-2019 a febrero-2020). En cada visita se realizo la prueba California (CMT), se evaluo suciedad de ubres y miembros posteriores de vacas lactantes y la rutina de ordeno. Se recolecto una muestra de leche por finca para determinar recuentos de celulas somaticas (RCS) y bacterias (RB). Modelos de regresion logistica mixtos se usaron para determinar factores asociados con tener o adquirir MSC, y modelos lineales generalizados para determinar factores asociados a mayor prevalencia de MSC y RB. Se realizaron 960 CMT a 454 vacas. Resultados. Se realizaron 960 CMT a 454 vacas. La prevalencia de MSC (mediana) a nivel-hato fue 50 %, y estuvo directamente asociada con RCS y RB. La incidencia acumulada (mediana), a nivel-hato, para desarrollar una infeccion nueva y una cronica fue 42 % y 75 %, respectivamente. Factores asociados con tener MSC fueron: multiparidad (Odds ratio: OR≥2,35), lactancia tardia (OR=3,39), no presellar (OR=1,74) y sobreordenar (OR=1,96). Factores que redujeron el riesgo de adquirir MSC fueron: tener no segregar (OR=2,42), ni presellar (OR=2,50). Factores asociados con elevados RB fueron: ubres sucias, tiempo de accion del presellador menor a 30 s y tener mas de un ordenador. Conclusion. Multiparidad, lactancia tardia (>180 dias en produccion), no segregar, no presellar y sobreordenar, fueron los factores que se asociaron con adquirir y tener mastitis subclinica, por lo tanto, se deben tener en cuenta en medidas de prevencion y control. EnglishIntroduction. Subclinical mastitis (SCM) is one of the main diseases in cattle; studying its epidemiology is essential to implement health programs. Objective. To determine the prevalence, incidence, and factors associated with subclinical mastitis in specialized dairies in Cundinamarca, Colombia. Materials and methods. An observational-analytical, prospective-cohort study was performed. Fifteen farms were visited three times every 56 days (September-2019 to February-2020). At each visit, the California test (CMT) was performed and dirtiness of udders and hind limbs of milking cows was evaluated; likewise, milking routine was evaluated. One milk sample per farm was collected to determine somatic cell counts (SCC) and bacteria count (BC). Logistic regression mixed models were used to determine factors associated with having or acquiring SCM, and generalized linear models to determine factors associated with the probability of a greater prevalence of SCM and BC. 960 CMT were performed on 454 cows. Results. A total of 960 CMT were performed on 454 cows. The median herd-level prevalence of SCM was 50 % and it was directly associated with SCC and BC. The median cumulative herd-level incidence of developing a new and a chronic infection of SCM was 42 % and 75 %, respectively. Factors associated with having SCM were: multiparous cows (Odds Ratio, OR≥2.35), late lactation (OR=3.39), no pre-dipping (OR=1.74), and over-milking (OR=1.96). Factors that reduced the risk of acquiring SCM were: having dirty udders, pre-sealer action time less than 30 s, and having more than one milker. Conclusion. Multiparous cows, late lactation (>180 days in production), not segregating, not pre-sealing, and over-milking, were factors associated with acquiring and having subclinical mastitis, therefore, they are key factors to consider in prevention and control measures.