Bactericidal effect of post-milking teat dip prepared from polysaccharide gel from durian rinds on streptococci causing clinical bovine mastitis

Antibacterial activity of polysaccharide gel (PG) extract from fruit-rinds of durian (Durio zibethinus) has been demonstrated against bovine mastitis bacterial isolates. Value added products derived from durian rind waste are an interesting goal. The present study aim to formulate and evaluate bactericidal effect of a postmilking teat dip prepared from PG. The teat dip preparation contain 2.5% PG (w/v) in 1% Ringer's solution with humectants including 10% propylene glycol and 10% glycerin was successfully prepared. In vitro time-kill analysis was examined against five streptococci isolates causing mastitis. The bacteria were incubated with the PG teat dip prepared in the presence of fetal bovine serum at 37 degrees C for 1-480 minutes. The result illustrated that bacterial counts of field isolates including S. agalactiae, S. dysagalactiae, S. uberis, S. bovis and S. acidominimus were reduced by more than 90% within 1 minute. Non-viable bacteria, S. agalactiae, after incubated with 2.5% PG in NSS were also examined under scanning electron microscope. Evaluation of the PG teat dip on inhibiting new intramammary infections (IMI) was studied in vivo by experimental challenge using S. agalactiae. Total of 162 quarters day at risk for new IMI were randomly assigned for a clinical trial in dairy cows, a study group dipped with the PG teat dip and the undipped group was control. Significant difference (P < 0.05) in total new IMI number observed between quarters in treated and control group, which was 0 (0%) and 5 (6.17%), respectively. The inhibition against new IMI was 100% after treated animal with teat dip prepared from PG.