Variability among morning and evening milk compositions during the lactation

The main objective of this study was to analyze milking-to-milking variability of milk yield and milk composition (such as fat and protein percentages and somatic cell count). Additional objective was to extend this analyze to the milk fat composition. Milk samples (n=195.960) were collected from 29.636 cows in 491 Luxembourg farms and analyzed by MIR spectrometry. The milk contents of saturated, mono-, poly- and unsaturated fatty acids, and short, medium and long chain fatty acids were predicted from the recorded MIR spectral data. As expected, the milk composition and the milk fat composition, are affected by several factors as the milking period and the days in milk. In practice, using separately milk evening and milk morning could be interesting for cheese or butter production.