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Table 4 Carbon dioxide emissions of lactating Holstein dairy cows with different metabolic weights1

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

Items2

LMW

MMW

HMW

SEM

P-value

Metabolic weight, kg

126.3c

136.4b

147.8a

2.89

0.026

Milk production and composition

 Milk yield, kg/d

38.7

38.5

36.8

2.02

0.057

 Milk fat, %

3.66

3.73

3.81

0.26

0.062

 Milk protein, %

3.22

3.28

3.37

0.29

0.059

 Total milk solids, %

12.4

12.3

12.7

1.03

0.826

 FCM yield, kg/d

36.7

36.9

35.6

2.34

0.068

 ECM yield, kg/d

37.4

37.5

36.5

2.62

0.084

Carbon dioxide emissions

 Total CO2, g/d

18,996

19,269

19,339

20.83

0.475

 Total CO2/MW, g/kg

150.6

141.3

131.1

4.03

0.063

 Total CO2/ECM, g/kg

517.6

530.6

546.6

9.13

0.078

  1. 1LMW low metabolic weight (< 131.7, n = 36), MMW medium metabolic weight (131.7–141.2, n = 42), HMW high metabolic weight (> 141.2, n = 33), n number of observations in the data set
  2. 2FCM 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. Total CO2, total CO2 production (g/d) = \( {\mathrm{CH}}_{4\left({\mathrm{CO}}_2-\mathrm{eq}\right)} \) (g/d) + CO2 production (g/d). MW metabolic weight (kg)
  3. a-c Means in the same row with different superscripts are significantly different (P < 0.05)