From: Mineral status and enteric methane production in dairy cows during different stages of lactation
Lactation stage1 | Statistics | ||||
---|---|---|---|---|---|
Items | Early | Middle | Late | SEM | P-value |
Yield | |||||
Milk, kg/d | 50.43a | 42.35b | 31.31c | 1.789 | < 0.0001 |
ECM,2 kg/d | 45.69a | 40.51a | 31.65b | 1.438 | < 0.0001 |
Fat, g/d | 1720a | 1544a | 1232b | 57.10 | < 0.001 |
Protein, g/d | 1483a | 1379a | 1119b | 43.90 | < 0.001 |
Casein, g/d | 1170a | 1089a | 883.5b | 34.97 | < 0.001 |
Lactose, g/d | 2500a | 2084b | 1511c | 91.36 | < 0.0001 |
Milk composition | |||||
Fat, % | 3.425 | 3.665 | 3.931 | 0.5543 | 0.053 |
Protein, % | 2.943a | 3.271b | 3.580c | 0.0646 | < 0.0001 |
Casein, % | 2.322a | 2.584b | 2.824c | 0.0526 | < 0.0001 |
Lactose, % | 4.958 | 9.924 | 4.819 | 0.0293 | 0.130 |
Dry matter, % | 11.97a | 12.48ab | 12.96b | 0.1228 | < 0.01 |
Urea, mg/L | 225.2a | 297.8b | 326.6b | 10.06 | < 0.0001 |
Somatic cells, 103/mL | 91.5 | 100.0 | 126.6 | 18.61 | 0.084 |
Urea/protein ratio | 76.63a | 91.32b | 91.69b | 2.339 | 0.007 |
Methane emission | |||||
Methane production, ppm | 606.9a | 507.9b | 471.2b | 12.87 | < 0.0001 |
Methane yield, ppm/kg DMI3 | 20.40a | 16.87b | 15.84b | 0.441 | < 0.0001 |
Methane intensity, ppm/kg ECM | 13.45ab | 12.47a | 15.44b | 0.457 | 0.020 |
CO2 production, ppm | 5611a | 4118b | 4447ab | 251.8 | < 0.05 |