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Table 8 True energy efficiency and heat production associated with milk production of sows fed Control (CON; 187.4 g/kg crude protein), Optimal (OPT; 137.8 g/kg crude protein) or Optimal + Leucine (OPTLEU; 142.5 g/kg) diets in early (day 4 to day 8), peak (day 14 to day 18) and overall (day 1 to day 21) lactation period1

From: Reduced protein diet with near ideal amino acid profile improves energy efficiency and mitigate heat production associated with lactation in sows

Item

Diet

SEM2

P-value

CON

OPT

OPTLEU

OPT vs. CON

OPT LEU vs. CON

OPTLEU vs. OPT

Early lactation (day 4 to 8)

 Number of sows3

12

11

11

    

MEmilk, MJ/d4

46.89

44.65

40.35

3.56

0.864

0.306

0.595

 MEintake

72.77

71.29

66.52

3.45

0.944

0.375

0.564

 MEmaintenance

25.94

26.76

26.02

0.58

0.442

0.992

0.502

Milk energy output from diet, MJ/d5

37.40

35.91

41.06

4.54

0.970

0.835

0.705

 Milk energy output

41.35

45.38

44.74

3.71

0.718

0.791

0.992

 Milk energy output from body

0.46

8.3

2.01

3.04

0.992

1.000

0.995

True energy efficiency, %6

79.9

78.8

94.0

7.0

0.993

0.333

0.293

 Milk energy from diet7

89.8

77.2

90.6

4.7

0.167

0.992

0.132

 Milk energy from body

10.2

22.8

9.4

4.7

0.167

0.992

0.132

Heat production associated with lactation8, kJ/(d·BW0.75)

160

132

30

64

0.944

0.319

0.504

Peak lactation (day 14 to 18)

 Number of sows3

11

11

11

    

MEmilk, MJ/d4

74.13*

72.51*

65.06*

3.56

0.928

0.114

0.222

 MEintake

100.30*

98.96*

91.31*

3.45

0.955

0.144

0.238

 MEmaintenance

26.26

26.26

26.31

0.58

0.999

0.997

0.996

Milk energy output from diet, MJ/d5

47.98*

61.44*

52.34*

4.54

0.112

0.780

0.347

 Milk energy output

51.76*

70.21*

58.09*

3.73

0.005

0.461

0.072

 Milk energy output from body

0.47

8.25*

2.00

3.04

0.992

1.000

0.995

True energy efficiency, %6

65.2

86.1

79.5

7.0

0.106

0.329

0.786

 Milk energy from diet7

90.6

86.8*

90.1

4.7

0.837

0.997

0.869

 Milk energy from body

9.4

13.2*

9.9

4.7

0.837

0.997

0.869

Heat production associated with lactation, kJ/(d·BW0.75)8

414*

165

211*

64

0.028

0.082

0.870

Over a 21-day lactation

 Number of sows3

11

9

9

    

MEmilk, MJ/d4

60.79

59.15

52.25

3.68

0.924

0.229

0.349

 MEintake

86.81

85.89

78.39

3.62

0.978

0.264

0.335

 MEmaintenance

26.07

26.74

25.95

0.64

0.670

0.987

0.617

Milk energy output from diet, MJ/d5

43.11

48.43

44.38

5.50

0.736

0.982

0.843

 Milk energy output

46.93

59.34

49.56

4.91

0.153

0.873

0.272

 Milk energy output from body

−0.62

9.40

1.67

3.82

0.241

0.900

0.410

True energy efficiency, %6

70.5

82.2

83.2

6.3

0.439

0.390

0.993

 Milk energy from diet7

91.6

81.6

88.3

5.3

0.425

0.898

0.668

 Milk energy from body

8.5

18.4

11.7

5.3

0.425

0.898

0.668

Heat production associated with lactation, kJ/(d·BW0.75)8

289

154

134

60

0.321

0.248

0.970

  1. 1Data are least squares means
  2. 2Maximum value of the standard error of the means
  3. 3Sows with an actual feed intake as percentage of predicted > 75% during days 4–8 and days 14–18; for over 21-day lactation, sows have energy balance for both early and peak lactation were used
  4. 4Metabolizable energy (ME) : MEmilk(MJ/d) = MEintake(MJ/d) − MEmaintenance(MJ/d)
  5. 5Milk energy output from diet(MJ/d) = Milk energy output(MJ/d) − Milk energy output from body(MJ/d)
  6. 6\( \mathrm{True}\ \mathrm{energy}\ \mathrm{efficiency}\left(\%\right)=\frac{\mathrm{Milk}\ \mathrm{energy}\ \mathrm{output}\ \mathrm{from}\ \mathrm{diet}\left(\mathrm{MJ}/\mathrm{d}\right)}{{\mathrm{ME}}_{\mathrm{milk}}\left(\mathrm{MJ}/\mathrm{d}\right)}\times 100\% \)
  7. 7\( \mathrm{Milk}\ \mathrm{energy}\ \mathrm{from}\ \mathrm{diet}\left(\%\right)=\frac{\mathrm{Milk}\ \mathrm{energy}\ \mathrm{output}\ \mathrm{from}\ \mathrm{diet}\left(\mathrm{MJ}/\mathrm{d}\right)}{\mathrm{Milk}\ \mathrm{energy}\left(\mathrm{MJ}/\mathrm{d}\right)} \)
  8. 8\( \mathrm{Heat}\kern0.34em \mathrm{production}\kern0.34em \mathrm{associated}\kern0.34em \mathrm{with}\kern0.34em \mathrm{lactation}\left[\mathrm{MJ}/\left(\mathrm{d}\bullet {\mathrm{BW}}^{0.75}\right)\right]=\frac{{\mathrm{ME}}_{\mathrm{milk}}\left(\mathrm{MJ}/\mathrm{d}\right)-\mathrm{milk}\ \mathrm{energy}\ \mathrm{output}\ \mathrm{from}\ \mathrm{diet}\left(\mathrm{MJ}/\mathrm{d}\right)}{{\mathrm{BW}}^{0.75}} \)
  9. *Main effect of period (early and late) was significant (P < 0.05).
  10. Main effect of period (early and late) tended to be significant for true energy efficiency (CON P = 0.086; OPTLEU P = 0.100).