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.