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Use of bulk tank milk fatty acid profiles as an on-farm decision-support tool.

D. E. Santschi




Use of bulk tank milk fatty acid profiles as an on-farm decision-support tool.
D. Warner, R. Lacroix, R. K. Moore, D. M. Lefebvre, D. E. Santschi*. Lactanet Sainte-Anne-de-Bellevue, QC, Canada.

Milk fatty acids (FA) originate from synthesis in the mammary gland (de novo), feed intake or body fat mobilization (preformed) or both origins (mixed). Rapid analysis of milk FA profiles through mid-infrared (MIR) spectroscopy could provide a valuable tool for feeding and management. Bulk tank samples from 3,395 dairy herds using milk recording in Quebec (CAN) are routinely tested by MIR. Samples (n = 573,000) between April 2019 and Feb 2020 were used to evaluate the use of FA as a monitoring tool. On a milk basis, each 0.1-unit increase in de novo FA was associated with an increase in fat by 0.201 units (R2 0.67) and true protein by 0.117 units (R2 0.65) whereas each 0.1-unit increase in preformed FA increased milk fat by 0.099 units (R2 0.23) but had no association with true protein (R2 0.01). Seasonal cycles showed decreased de novo and increased preformed FA during the summer months (FA basis). JE herds had a lesser drop in de novo FA than HO herds (−0.7 vs −1.3 g/100 g FA, respectively, for August vs April). Across seasons, JE herds had higher de novo (+1.5 g/100 g FA) but lower preformed FA (−2.9 g/100 g FA) and an overall greater milk fat content (+0.8%-units) as compared with HO herds. A snapshot analysis was conducted with herd averages for April 2019 for 2035 HO herds having high de novo (>median; HDN; mean � SD of 27.9 � 0.73 g/100 g FA) and low de novo (<median; LDN; 25.9 � 1.14 g/100 g FA) levels. A mixed model approach was used in R with Gaussian distribution for continuous variables, and with binomial distribution and log-link function for variables with binary outcome, considering herd as a random effect. No differences existed in herd size, days in milk, and conventional vs organic, but HDN herds had higher odds (2.0; P ≤ 0.01) of having a positive Transition Cow Index and lower odds (0.80; P = 0.02) of having a somatic cell count of 200 or more on test day. HDN herds had a 0.89 kg greater (P ≤ 0.01) milk yield per cow on test day. A graphical and interactive tool was developed to visualize milk FA profiles with respective benchmarks and farm-specific historical data, was tested on farm and deployed in production via an IBM Cognos platform.

Keywords: fatty acid, Fourier-transform infrared, decision-support.