“…Mean and median values were similar for all variables in this data set. A significant curvilinear relationship (R 2 = 0.19) was found between milk yield and the concentration of CP All data were taken or calculated from experiments reported in 112 independent studies (Barney et al, 1981;Mielke and Schingoethe, 1981;van Dijk et al, 1983;Henderson et al, 1985;Polan et al, 1985Polan et al, , 1997Van Horn et al, 1985;Broderick, 1986Broderick, , 1992Broderick, , 2003Lundquist et al, 1986;Annexstad et al, 1987;Garnsworthy and Jones, 1987;Howard et al, 1987;Jaquette et al, 1987;Kaim et al, 1987;Bowman et al, 1988;Hadsell and Sommerfeldt, 1988;Jones and Garnsworthy, 1988;Léonard and Block, 1988;Manson and Leaver, 1988;Robinson and Kennelly, 1988;Schingoethe et al, 1988;Sloan and Rowlinson, 1988;Voss et al, 1988;Bruckental et al, 1989Bruckental et al, , 2000De Gracia et al, 1989;Garnsworthy, 1989;Herrera-Saldana and Huber, 1989;Higginbotham et al, 1989;Mä ntysaari et al, 1989;Blauwiekel et al, 1990;Broderick et al, 1990Broderick et al, , 1993Canfield et al, 1990;Casper et al, 1990Casper et al, , 1999…”