Objectives of this study were to analyze (a) differential bacteria tests on bulk tank milk; and (b) pipeline cleaning cycle temperatures on 4 Michigan dairy farms. Individual bulk tank milk samples were taken on randomly selected separate days (n = 3) over a 2-wk period and submitted to Eastern Lab Services (Medina, OH). Milk differential bacterial tests included standard plate (SPC), preliminary incubation (PI), laboratory pasteurization (LPC), coliform counts (CC), and bulk tank milk cultures (only once). Bacteria counts were compared with industry quality benchmarks (SPC <5,000 cfu/mL; PI <10,000 cfu/mL; LPC <100 cfu/mL; CC <100 cfu/mL) with single milk culture test used to rule out mastitis-causing bacteria or poor pre-milking teat sanitation bacterial sources. Milking pipeline cleaning cycle temperatures were recorded on 1 complete cleaning sequence following milking on test days using a sterilized Thermocron iButton, sealed inside each milking system wash vat before start of a complete cleaning cycle. Recorded temperatures were compared with recommend cleaning cycle temperatures, especially detergent cycles (>120°F at cycle end). Farms A and C had all differential bacteria counts better than industry quality benchmarks. Farm B showed elevated SPC on 1 d (18,000 cfu/mL) and elevated PI counts on 2 d (1,421,000 and 14,000 cfu/mL) while farm D had one elevated SPC (7000 cfu/mL) and one elevated PI (374,000 cfu/mL). LPC on both farms (B & D) were <100 cfu/mL, indicating clean milking equipment. Milk culture tests indicated elevated levels of Strep. non-ag. and Staph. species at Farms B (5000 and 3500 cfu/mL) and D (1500 and 400 cfu/mL) indicating potential issues with proper teat pre-milking sanitation. All farms met industry standards for initial rinse and acid rinse cycles (85–95°F) and detergent cycles (<160°F at start and >120°F at end). Overall, this study found excellent differential bacteria counts on 2 farms over a 2-wk period, while 2 farms showed elevated SPC and PI. Further differential tests showed low LPC (clean equipment) and pre-milking sanitation issues as the most likely problem (milk culture). All farms had proper detergent cycle cleaning temperatures that correlated with low LPC.