Table 3. Effects of intravenous infusions of amino acids (AA) on feed intake, and milk composition and production of Holstein dairy cows

Item Treatment1) SED p-value
Control 4AA no-Met no-Lys
Dry matter intake (kg/d)
 Concentrates 12.1 12.1 12.1 12.1 -
 Corn silage 2.5 2.5 2.5 2.5 -
 Alfalfa hay 0.9 0.9 0.9 0.9 -
 Timothy hay 4.9 5.9 5.1 5.2 0.42 0.185
 Total 20.4 21.4 20.6 20.7 -
Milk yield (kg/d) 31.2 32.4 31.3 31.7 0.64 0.284
 Fat (g/kg) 31.6 32.9 34.0 33.0 1.74 0.617
 Fat (g/d) 987 1,067 1,068 1,049 45.0 0.318
 Protein (g/kg) 29.3a 30.8b 29.1a 30.7b 0.44 0.015
 Protein (g/d) 913a 997b 910a 970b 18.3 0.008
 Lactose (g/kg) 48.1b 48.0b 48.4c 47.6a 0.11 0.003
 Lactose (g/d) 1,503 1,561 1,518 1,509 30.3 0.305
Control, no infusion; 4AA, mixture of 6 g/d methionine, 19.1 g/d lysine, 13.8 g/d isoleucine and 15.4 g/d valine; no-Met, mixture without methionine; no-Lys, mixture without lysine.
Means with different letters within a row differ at p < 0.05.
SED, standard error of the differences.