English

Abstract

The objective of this study was to assess the performance and welfare (lameness, hock lesions, mastitis) of loose-housed dairy cattle managed under grazing or semi-grazing system. Data of thirty-two cows before and after changing to semi-grazing system during the rainy season (week 1 to 4; grazing, week 6 to 9; semi-grazing) and before and after changing to semi-grazing (week 11 to 16; grazing, week 18 to 23, semi-grazing) during the dry season were examined. Cows were evaluated weekly for 24 weeks for somatic cell count (SCC), lameness, hock lesions, and hygiene. Milk yield was collected daily. Bacteria cultures were prepared to identify pathogens. Isolates were subjected to sensitivity tests. No difference was observed between grazing and semi-grazing, regarding milk yield, lameness, hock lesions, SCC, and sub-clinical mastitis prevalence. Mean SCC under grazing was >600,000 cells/ml, indicating infection with major pathogens (Streptococcus agalatiae, Streptococcus dysgalatiae). Klebsiella species increased with season and were less sensitive to common antibiotics. Contagious pathogens in milk were lower (14%) compared with environmental pathogens (82%). Because Klebsiella species were less sensitive to many antibiotics, keeping cows healthy is critical. Focus on reducing somatic cell count will be important in preventing mastitis infection in dairy cows. Key words: Grazing, semi-grazing system, performance, cattle welfare.