Fig. 3

Trends in milk composition traits of the F₃ cows per pregnancy month of their F₀ and F₁ ancestors. Left and right y-axes represent the mean least squares (MLS) of the potential transmitting abilities (PTA) for fat and protein yields, respectively, as functions of the birth month of the cows’ dams and maternal grand-dams. “fat-g” and “prot-g” are MLS of the cows’ fat and protein yields, respectively, as functions of the maternal grand-dams’ birth month; and “fat-m” and “prot-m” are MLS of the cows’ fat and protein yields, respectively, as functions of dams’ birth month. The error bars are the MLS standard errors. Gray and blue vertical dashed lines denote the positive (March to June) and negative (September to January) trend thresholds, respectively. Gray and blue double-headed arrows denote the boundaries of the threshold intervals