Amino acid digestibility in Lemna Protein Concentrate fed to weanling pigs

Lemna Protein Concentrate is derived from the leaves of duckweed, one of several rapidly-growing aquatic plants of the genus Lemna. Duckweed has a number of advantages as a protein source. It is relatively inexpensive to produce and requires less growing area and fewer inputs than other plant protein sources such as soybean products. It also contains relatively little fiber, making it a highly digestible feed ingredient.

An experiment was conducted to determine the digestibility of amino acids and crude protein in Lemna Protein Concentrate fed to weanling pigs and to compare these values to digestibility values obtained for soybean meal and fish meal.

The experiment

Eight weanling barrows were fed one of four diets. One diet contained 40% soybean meal and no other source of amino acids. Another diet contained 20% soybean meal and 20% Lemna Protein Concentrate, and a third diet contained 20% soybean meal and 15% fish meal. Finally, a nitrogen-free diet was used to determine basal endogenous losses of protein and amino acids.

Amino acids in Lemna Protein Concentrate are well digested by young pigs

For crude protein and most amino acids, standardized ileal digestibility (SID) values were greatest in soybean meal, followed by fish meal, followed by Lemna Protein Concentrate (Table 1). However, digestibility of tryptophan in Lemna Protein Concentrate was the same as in soybean meal, and digestibility of histidine in Lemna Protein Concentrate was the same as in fish meal. Although digestibility values for Lemna Protein Concentrate were generally the least among the three ingredients tested, crude protein and amino acids in Lemna Protein Concentrate were well digested by the weanling pigs, with a mean SID value of 81.70% for all amino acids.

Due to its high protein content, Lemna Protein Concentrate contained greater concentrations of standardized ileal digestible crude protein and all indispensable amino acids than soybean meal (Table 2). Lemna protein Concentrate and fish meal contained similar concentrations of SID crude protein and many amino acids. A notable exception was SID lysine, of which there was a significantly greater concentration in fish meal than in Lemna Protein Concentrate.

Key points

  • Crude protein and amino acids in Lemna Protein Concentrate are as well or nearly as well digested by weanling pigs as crude protein and amino acids in fish meal and soybean meal.
  • Lemna Protein Concentrate contains a greater concentration of standardized ileal digestible protein and amino acids compared with soybean meal, and similar amounts of digestible protein and many amino acids compared as in fish meal.
  • Lemna Protein Concentrate may be a suitable protein source in weanling pig diets, but performance experiments need to be conducted to confirm this hypothesis.

 

Table 1.Standardized ileal digestibility (SID) of crude protein and amino acids in Lemna protein, fish meal, and soybean meal (SBM) by weanling pigs

 

Ingredient

 

Item

Lemna protein

Fish meal

SBM

P-value

  CP, %

79.09c

83.22b

94.89a

< 0.01

Indispensable AA, %

  Arg

89.21c

92.23b

97.92a

< 0.01

  His

82.16b

84.28b

93.99a

< 0.01

  Ile

80.97c

85.73b

92.62a

< 0.01

  Leu

81.09c

86.44b

92.30a

< 0.01

  Lys

82.90c

87.52b

94.84a

< 0.01

  Met

81.28c

88.95b

97.03a

< 0.01

  Phe

81.79c

85.52b

90.92a

< 0.01

  Thr

76.27c

82.12b

91.64a

< 0.01

  Trp

90.53a

83.62b

92.16a

< 0.01

  Val

80.42c

84.07b

91.90a

< 0.01

Mean

82.26c

86.44b

93.66a

< 0.01

Dispensable AA, %

  Ala

79.34c

84.26b

94.61a

< 0.01

  Asp

83.29b

77.42c

89.35a

< 0.01

  Cys

65.51c

75.10b

83.33a

< 0.01

  Glu

87.26

87.78

90.00

0.4

  Gly

79.78b

84.72b

100.97a

< 0.01

  Pro

105.75b

121.51ab

151.12a

0.07

  Ser

75.24c

85.52b

91.34a

< 0.01

  Tyr

83.46c

86.79b

90.84a

< 0.01

Mean

81.09b

86.73b

98.16a

< 0.01

All AA

81.70c

86.70b

95.95a

< 0.01

 

 

Table 2.Concentrations of as-fed and standardized ileal digestible crude protein and amino acids in Lemna protein, fish meal, and soybean meal (SBM) by weanling pigs

 

Concentration

 

Standardized ileal digestible protein

 

Ingredient

 

Ingredient

Item

Lemna protein

Fish meal

SBM

 

Lemna protein

Fish meal

SBM

  CP, %

67.99

63.16

41.33

 

53.77

52.56

39.22

Indispensable AA, %

  Arg

4.11

3.82

2.80

 

3.67

3.52

2.74

  His

1.59

1.41

0.99

 

1.31

1.19

0.93

  Ile

3.09

2.57

1.69

 

2.50

2.20

1.57

  Leu

5.95

4.49

3.05

 

4.82

3.88

2.82

  Lys

3.50

4.81

2.34

 

2.90

4.21

2.22

  Met

1.38

1.77

0.54

 

1.12

1.57

0.52

  Phe

3.92

2.47

1.99

 

3.21

2.11

1.81

  Thr

2.88

2.59

1.52

 

2.20

2.13

1.39

  Trp

1.16

0.65

0.52

 

1.05

0.54

0.48

  Val

3.89

3.12

1.87

 

3.13

2.62

1.72

Dispensable AA, %

  Ala

4.08

3.97

1.73

 

3.24

3.35

1.64

  Asp

5.62

5.65

4.24

 

4.68

4.37

3.79

  Cys

0.73

0.57

0.56

 

0.48

0.43

0.47

  Glu

6.69

8.53

7.06

 

5.84

7.49

6.35

  Gly

3.69

4.68

1.71

 

2.94

3.96

1.73

  Pro

2.83

2.94

1.99

 

2.99

3.57

3.01

  Ser

2.46

2.35

1.80

 

1.85

2.01

1.64

  Tyr

2.98

2.02

1.44

 

2.49

1.75

1.31

 

This research report is based on unpublished research by H. H. Stein.

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