Bacterial agents and somatic cell counts in milk from dual purpose bovines milked by hand or by mechanical procedures in four dairy farms from Zulia state, Venezuela

Se identificaron agentes bacterianos y se determinó contaje de células somáticas (CSS) en leche de 160 cuartos de 40 bovinos mestizos doble propósito, 20 ordeñados en forma manual (AOM) y 20 en forma mecánica (AOME), de 4 fincas del estado Zulia, Venezuela. Las bacterias se identificaron por métodos bioquímicos convencionales y el CCS se determinó por el método rápido SomaLite. Se encontró que 68,83% de los cuartos presentaron al menos un patógeno mastitogénico: 54,66% en los AOM y 82,27% en los AOME. Se identificaron 139 cepas, 39% aisladas de AOM y 61% de AOME. Los principales géneros en AOM fueron Staphylococcus spp. (65%) y Corynebacterium spp. (24%), mientras que para AOME fueron Staphylococcus spp. (67%) y Streptococcus spp. (20%). Las principales especies aisladas de AOM fueron C. bovis, St. intermedius, St. caseolyticus y St. simulans y para AOME fueron St. intermedius, S. agalactiae, St. aureus y St. hominis. El CCS de AOME (6,54 Log10 CCS) fue más elevado que para AOM (5,77 Log10 CCS), esta tendencia se mantuvo para todos los géneros bacterianos. El CCS más elevado de acuerdo a género correspondió a Streptococcus spp. y Bacillus spp. Para AOM se encontraron los más elevados CCS para las muestras infectadas con B. polymyxa, S. bovis, St. capitis, St. piscifermentas y St. aureus. Para AOME correspondieron a B. macerans, B. polymixa, S. agalactiae, St. simulans y St. aureus. Se concluye que en la leche obtenida de animales ordeñados mecánicamente predomina la presencia de patógenos mayores que provocan inflamación de la glándula mamaría reflejada en un elevado contaje de células somáticas.64 - 71BimestralIdentification of bacterial agents and somatic cell counts (SCC) were made from the milk of 160 quarters of dual purpose bovines, 20 by hand milking (HM) and 20 by mechanical milking (MM), belonging to 4 farms in Zulia State, Venezuela. The bacterial identification was made by standard biochemical methods and the SCC was made by the Somalite fast method. It was found that 68.83% of all quarters had at least one mastitogenic pathogen, 54.66% (HM) and 82.27% (MM). One hundred thirty nine strains were indentified, 39% isolated from HM and 61% from MM. The principal genus from HM were Staphylococcus spp (65%) and Corynebacterium spp (24%), while for MM they were Staphylococcus spp (67%) and Streptococcus spp (20%). The principal strains from HM were C. bovis, St. intermedius, St. caseolyticus and St. simulans and from MM were St. intermedius, S. agalactiae, St. aureus and St. hominis. The MM SCC (6.54 Log10 CCS) was higher than HM (5,77 Log10 CCS). This was the tendency for all the bacterial genus. The higher SCC according to the genus was correlated with Streptococcus spp. and Bacillus spp. HM was founded to be the highest in SCC for the samples infected with B. polymyxa, S. bovis, St. capitis, St. piscifermentas and St. aureus. To MM B. macerans, B. polymixa, S. agalactiae, St. simulans and St. aureus corresponded. It is concluded that the presence of major bacterial pathogens that cause inflammation reflected in an elevated SCC predominated in milk from mechanical milking