Using time-temperature recorder data on dairy farms to identify short-term factors associated with increased free fatty acids in bulk tank milk

Elevated concentrations of free fatty acids (FFA; ≥1.20 mmol/100 g of fat) reduce milk quality by changing milk sensory and functional properties. Bulk tank FFA levels vary between milk pickups, and there is limited research to identify factors associated with these short-term fluctuations in FFA. A time-temperature recorder (TTR) may be used on dairy farms to identify milk quality concerns through producer alarms related to milk cooling, storage, and contact surface sanitization. The objective of this study was to investigate whether specific TTR alarms could be associated with short-term increases in bulk tank milk FFA. An observational cross-sectional study was conducted, and data from TTR units on 177 farms in Ontario, Canada, were collected and analyzed. A subset of 751 alarms from 120 farms was used. For each alarm, the baseline FFA concentration (average FFA across 7 pickups before the alarm, if no alarm present) was compared with the alarm-associated FFA. The average FFA for all bulk tank milk samples associated with any single TTR alarm (0.90 ± 0.50 mmol/100 g of fat) was greater than the baseline average FFA (0.88 ± 0.41 mmol/100 g of fat). More than 15% (n = 113) of TTR alarm-associated samples were elevated (≥1.20 mmol/100 g of fat). Observations from a bulk tank sample with a "milk too cold" alarm had the highest average FFA (1.31 mmol/100 g of fat) and were the only ones with a significant increase in FFA compared with the baseline. Using a mixed linear regression model, the associated increase in FFA was 0.36 mmol/100 g of fat when a "milk too cold" TTR alarm occurred. The absence of additional cooling was also a risk factor for increased FFA and a "milk too cold" alarm. These results suggest that a "milk too cold" TTR alarm could help explain short-term increases in FFA on dairy farms with bulk tank milk temperature recording.