Comparative digestibility of energy and nutrients in diets fed to sows and growing pigs

Results of experiments in Europe have indicated that the apparent total tract digestibility (ATTD) of gross energy and nutrients, as well as the concentration of digestible (DE) and metabolizable (ME) energy, is greater in gestating sows fed close to their maintenance requirement than in growing pigs allowed ad libitum access to feed.

However, no data from North America for the comparative digestibility of energy and nutrients in sows and growing pigs have been reported. Therefore, an experiment was conducted to compare the digestibility of energy and nutrients in sows and growing pigs. A second objective was to develop equations to predict digestibility of energy and nutrients in sows from digestibility values obtained in growing pigs.

Experimental design

A total of 88 gestating sows (parity 2 to 6) as well as 88 growing barrows with an average initial body weight of 40.1 kg were used in the experiment. Eleven diets were formulated. The three cereal grain diets were based on corn, sorghum, and wheat. The remaining eight diets were based on a combination of corn and one of eight ingredients. Four of the ingredients were common sources of plant protein: soybean meal, canola meal, conventional distillers dried grains with solubles (DDGS-CV), and low-fat DDGS (LF-DDGS). Four other ingredients were commonly used high fiber ingredients: corn germ meal, corn bran, wheat middlings, and soybean hulls.

Sows and growing pigs were fed the same diets. Feed was provided in two equal meals per day for a total of 1.5 and 3.4 times the estimated energy requirement for maintenance in gestating sows and growing pigs, respectively. Fecal and urine samples were collected and analyzed to calculate the ATTD of gross energy (GE), crude protein (CP), acid detergent fiber (ADF), and neutral detergent fiber (NDF), and the concentrations of DE and ME in each diet.

Energy and crude protein digestibility were greater in sows than in growing pigs

For all of the grain diets, the ATTD of GE and CP, and the concentrations of DE and ME, were greater (P < 0.05) for gestating sows than for growing pigs (Table 1).There was also a tendency for the ME:DE ratio to be greater in gestating sows than in growing pigs.

For the diets containing protein ingredients, the ATTD of GE and CP and the concentration of DE was greater (P < 0.05) for sows than for pigs (Table 2).There was no difference in ME or in the ME:DE ratio between sows and pigs.

For the high fiber diets, the ATTD of CP and the ME:DE ratio were greater (P < 0.05) for sows than for pigs (Table 3). The ATTD of GE was greater (P < 0.05) for sows fed the wheat middlings diet or the soybean hulls diet than for pigs, but there was no difference between sows and pigs fed the corn germ meal diet or the corn bran diet. The concentrations of DE and ME for the wheat middlings diet and the soybean hulls diet were greater (P < 0.05) for sows than for pigs, but there was no difference in DE and ME values between sows and pigs fed the corn germ meal diet or the corn bran diet.

Results for fiber digestibility were mixed

The ATTD of ADF was greater (P < 0.05) for growing pigs fed the wheat, soybean meal, or corn germ meal diets than for gestating sows. The ATTD of NDF was greater (P < 0.05) for growing pigs fed wheat or canola meal than for gestating sows.

The ATTD of ADF was greater (P < 0.05) for sows fed soybean hulls than for pigs. The ATTD of NDF was greater (P < 0.05) for sows fed corn, DDGS-CV, and soybean hulls than for pigs.

No difference was observed between sows and pigs in the ATTD of ADF in corn, sorghum, canola meal, DDGS-CV, LF-DDGS, corn bran, or wheat middlings. There was no difference in the ATTD of NDF between sows and pigs fed sorghum, soybean meal, LF-DDGS, corn germ meal, corn bran, or wheat middlings.

Results of previous research indicated that sows are able to utilize fiber more efficiently than growing pigs because their greater intestinal volume allows for more fermentation of fiber. This experiment did not confirm that difference. One possible reason is that both sows and pigs were allowed to adapt to their diets for 20 days before fecal collection began. The adaptation period may have allowed the growing pigs to adapt to the fiber by increasing hindgut size and thus fermentation.

Predicting digestibility in sows from values obtained in growing pigs

The ATTD of GE and CP, and the DE values for gestating sows could be predicted from the values obtained in growing pigs by using the following equations:

ATTD of GE, %  22.7553 + 0.7506*ATTDGEpig  R2 = 0.78

ATTD of CP, %  27.2137 + 0.7232*ATTDCPpig  R2 =0.72

DE, kcal/kg DM  911.57 + 0.7727*DEpig  R2 = 0.78

Prediction equations were developed for ATTD of ADF, NDF, and ME values for gestating sows as well; however, the R2 values for these equations were 0.55, 0.36, and 0.54 respectively.

Key points

  • The apparent digestibility of gross energy and crude protein, as well as concentrations of digestible and metabolizable energy observed in gestating sows were greater than values observed in growing pigs.
  • The apparent digestibility of fiber obtained in gestating sows was not different from values obtained in growing pigs for most ingredients.
  • The ATTD of GE and CP, and DE values in gestating sows may be predicted from the values obtained in growing pigs.

Table 1. Comparative digestive utilization of corn, wheat, or sorghum diets between gestating sows and growing pigs

 

Corn

Wheat

Sorghum

P-value

Item

Sows

Pigs

Sows

Pigs

Sows

Pigs

Diet

Stage

Diet*stage

ATTD of GE, %

88.23

85.84

90.85

89.26

88.88

85.94

<0.01

<0.01

0.70

ATTD of CP, %

84.96

66.98

91.97

85.67

73.30

61.85

<0.01

<0.01

0.14

ATTD of ADF, %

56.99a

53.66a

16.79c

30.72b

65.28a

64.58a

<0.01

0.55

<0.05

ATTD of NDF, %

76.24b

66.24c

66.16c

72.55b

89.38a

86.99a

<0.01

0.22

<0.01

DE, kcal/kg, as-fed

3,321

3,231

3,420

3,360

3,342

3,231

<0.01

<0.01

0.71

ME, kcal/kg, as-fed

3,223

3,037

3,296

3,212

3,278

3,093

<0.05

<0.01

0.33

DE, kcal/kg, DM

3,780

3,678

3,858

3,790

3,830

3,703

<0.05

<0.01

0.70

ME, kcal/kg, DM

3,669

3,457

3,718

3,623

3,757

3,545

<0.05

<0.01

0.33

ME/DE, %

85.26

82.45

85.42

84.60

84.58

83.37

0.40

0.07

0.54

a-cLeast square means within a row lacking a common superscript letter are different (P < 0.05).

Table 2. Comparative digestive utilization of diets containing soybean meal (SBM), canola meal (CM), conventional distillers dried grains with solubles (DDGS-CV), or low-fat distillers dried grains with solubles (LF-DDGS) between gestating sows and growing pigs

  SBM CM DDGS-CV LF-DDGS P-value
Item Sows Pigs Sows Pigs Sows Pigs Sows Pigs Diet Stage Diet * stage
ATTD of GE, % 87.40 87.22 81.06 80.48 82.48 78.59 82.37 80.56 <0.01 <0.05 0.17
ATTD of CP, % 88.46 87.41 82.68 77.62 85.43 81.08 85.36 80.64 <0.01 <0.01 0.34
ATTD of ADF, % 50.44bc 59.57a 27.84e 34.60de 47.85bc 42.11cd 48.21bc 54.84ab <0.01 0.08 <0.05
ATTD of NDF, % 76.07a 73.43ab 54.45e 61.34d 70.35b 59.48de 69.05bc 63.41cd <0.01 0.07 <0.01
DE, kcal/kg, as-fed 3,341 3,365 3,151 3,122 3,488 3,317 3,369 3,288 <0.01 0.05 0.08
ME, kcal/kg, as-fed 3,165 3,203 2,950 2,969 3,279 3,143 3,164 3,202 <0.01 0.83 0.35
DE, kcal/kg, DM 3,779 3,807 3,554 3,522 3,924 3,732 3,796 3,705 <0.01 0.05 0.08
ME, kcal/kg, DM 3,581 3,624 3,328 3,349 3,689 3,536 3,565 3,607 <0.01 0.83 0.35
ME/DE, % 83.71 84.05 83.58 83.86 83.55 84.00 83.36 86.15 0.76 0.24 0.61

a-eLeast square means within a row lacking a common superscript letter are different (P < 0.05).

 

Table 3. Comparative digestive utilization of diets containing corn germ meal (CGM), corn bran, wheat middlings (WM), or soybean hulls (SBH) between gestating sows and growing pigs

 

CGM

Corn bran

WM

SBH

P-value

Item

Sows

Pigs

Sows

Pigs

Sows

Pigs

Sows

Pigs

diet

Stage

diet

*stage

ATTD of GE, %

82.73ab

83.94a

79.45bcd

79.23bcd

84.13a

78.91cd

80.75abc

75.76d

<0.01

<0.05

<0.05

ATTD of CP, %

80.60

77.18

71.53

70.21

82.98

71.36

63.09

57.50

<0.01

<0.01

0.16

ATTD of ADF, %

61.72b

75.38a

55.49b

60.47b

34.18c

34.66c

79.48a

53.51b

<0.01

0.43

<0.01

ATTD of NDF, %

82.19a

85.84a

67.77bc

72.41b

65.66c

66.70bc

81.10a

62.11c

<0.01

0.15

<0.01

DE, kcal/kg, as-fed

3,160a

3,206a

3,102ab

3,092ab

3,208a

3,010b

3,010b

2,825c

<0.01

<0.05

<0.05

ME, kcal/kg, as-fed

3,009ab

3,086a

3,000abc

2,947abc

3,094a

2,850cd

2,924bc

2,703d

<0.01

<0.05

<0.05

DE, kcal/kg, DM

3,548abc

3,600ab

3,466bcd

3,455bcd

3,637a

3,411cd

3,369d

3,161e

<0.01

<0.05

<0.05

ME, kcal/kg, DM

3,379ab

3,465a

3,352ab

3,293b

3,507a

3,230b

3,272b

3,026c

<0.01

<0.05

<0.05

ME/DE, %

80.60

77.18

71.53

70.21

82.98

71.36

63.09

57.50

<0.01

<0.01

0.16

a-dLeast square means within a row lacking a common superscript letter are different (P < 0.05).

This report is based on research conducted by Jessica Lowell and Hans Stein, and published in Jessica Lowell's master's thesis.

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