Evaluation of the appropriate diagnostic tools for intra-mammary infection in lactating dairy goats

Abstract

Sixty milk samples of healthy, lactating dairy goats were collected by an aseptic, hand milking technique. All samples were analyzed using milk quality tests: bacterial isolation (Bac), total plate count (TPC), dye reduction test (DRT) and clot-on-boiling test (COB), as well as screening tests: the Californian mastitis test (CMT) and electrical resistance (ER), and somatic cell count (SCC) and percentage of milk composition including fat, protein, lactose and solid-not-fat (SNF). According to 34 samples for intra-mammary infection (IMI) and 26 samples for non-IMI, the results showed that Bac and TPC were the most reliable techniques for the determination of IMI with strong correlations. For an instantaneous milk quality test, CMT reaction was probably more reliable as there was a statistical significance between bacteriologically positive and negative samples (P = 0.06). Moreover, CMT showed a correlation with TPC, Bac, DRT, ER, ER ref, SCC, milk protein, and milk lactose (P ≤ 0.05). Based on the range in ER, TPC showed a statistically significant difference between the ER level being less than 350 units and higher than 400 units (P ≤ 0.05). Except for CMT reactions, SCC did not correlate to other measurements and did not indicate the IMI status of goats. These findings indicated that there was a need for future improvement in the diagnostic tools for IMI in goats.