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Table 2 Feed intake, milk production and composition and carbon dioxide emission of lactating Holstein dairy cows (na = 111)

From: Characterization and mitigation option of greenhouse gas emissions from lactating Holstein dairy cows in East China

Itemsb Mean Minimum Maximum SDc
Animal description
 Age, months 51.7 36.3 89.9 12.7
 Parity number 2.8 2.0 5.0 1.0
 Days in milk, d 138 104 182 19
 Metabolic weight, kg 136.5 116.4 160.1 9.5
 Dry matter intake, kg/d 23.1 17.6 33.7 2.6
Milk production and composition
 Milk yield, kg/d 38.1 25.9 53.7 6.9
 Feed efficiency, kg/kg 1.65 0.62 2.32 0.29
 Milk fat yield, g/d 1414 545 2222 272
 Milk protein yield, g/d 1247 446 1991 236
 Total milk solids yield, g/d 4720 1811 6295 786
 FCM yield, kg/d 36.4 29.8 54.8 6.6
 ECM yield, kg/d 37.2 31 55.1 6.7
Greenhouse gas emissions
\( {\mathrm{CH}}_{4\left({\mathrm{CO}}_2-\mathrm{eq}\right)} \), g/d 8304 5392 11,190 1151
\( {\mathrm{CH}}_{4\left({\mathrm{CO}}_2-\mathrm{eq}\right)} \)/DMI, g/kg 359.4 227.1 492.6 48.3
\( {\mathrm{CH}}_{4\left({\mathrm{CO}}_2-\mathrm{eq}\right)} \)/MW, g/kg 61.1 41.1 86.6 9.3
\( {\mathrm{CH}}_{4\left({\mathrm{CO}}_2-\mathrm{eq}\right)} \)/ECM, g/kg 229.5 149.8 455.0 48.1
 Total CO2, g/d 19,201 14,412 24,145 2004
 Total CO2/DMI, g/kg 831.5 575.2 976.7 84.1
 Total CO2/MW, g/kg 141.3 101.1 183.5 17.3
 Total CO2/ECM, g/kg 531.1 343.3 1095.6 102.8
  1. an, number of observations in the data set
  2. bFeed efficiency, milk yield ÷ dry matter intake (kg/kg). FCM Fat-corrected milk (kg/d) = 0.4 × milk yield (kg/d) + 15 × fat yield (kg/d). ECM Energy-corrected milk (kg/d) = milk yield (kg/d) × [(38.3 × fat (%) × 10 + 24.2 × protein (%) × 10 + 16.54 × lactose (%) × 10 + 20.7) ÷ 3140]. \( {\mathrm{CH}}_{4\left({\mathrm{CO}}_2-\mathrm{eq}\right)} \), the CH4 emission in the experiment was expressed as CO2 equivalent, \( {\mathrm{CH}}_{4\left({\mathrm{CO}}_2-\mathrm{eq}\right)} \) (g/d) = CH4 emissions (g/d) × 25. DMI dry matter intake (kg/d). MW metabolic weight (kg). Total CO2, total CO2 production (g/d) = \( {\mathrm{CH}}_{4\left({\mathrm{CO}}_2-\mathrm{eq}\right)} \) (g/d) + CO2 production (g/d)
  3. cSD Standard deviation