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

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

Items^b	Mean	Minimum	Maximum	SD^c
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

^an, number of observations in the data set
^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)
^cSD Standard deviation

ISSN: 2049-1891