Effects of two direct fed microbials on ileal digestibility of amino acids and total tract digestibility of crude protein and gross energy in diets fed to growing pigs

Direct fed microbials (DFM) are defined as live microorganisms that offer a health benefit for the host when administered in appropriate and regular quantities. Bacillus-based DFM are aerobic, spore-forming bacteria that may enhance the host animal’s immune response and improve growth performance in weanling pigs. Bacillus spp. also produce extracellular enzymes that may enhance digestibility and absorption of nutrients.

An experiment was, therefore, conducted to test the hypothesis that two DFM containing Bacillus strains (provided by Chr. Hansen A/S, Horsholm, Denmark) improve the apparent ileal digestibility (AID) of AA, CP, and GE, the apparent total tract digestibility (ATTD) of CP and GE, and hindgut digestibility of CP and GE when fed to growing pigs.

 

Experimental design

Twenty-four growing barrows (22.69 ± 1.48 kg initial body weight) with a T-cannula in the distal ileum were individually housed and randomly allotted to a 24 × 3 incomplete Latin square design with 24 pigs and three 21-d periods. There were 8 pigs per diet in each period for a total of 24 observations per diet. Three diets that were based on corn, soybean meal, and distillers dried grains with solubles were formulated. The control diet contained no DFM, but 2 additional diets contained 2 different bacillus strains (DFM1 or DFM2). Feed was provided in mash form in 2 daily meals at 0800 and 1600 h. The initial 12 d of each period was the adaptation period to the diet. Fecal and urine samples were collected from d 13 to 18, and ileal digesta were collected for 8 hours on d 20 and 21.

 

Results

There were no differences in ATTD of CP among diets, but the AID of CP was reduced (P < 0.05) in the DFM2 diet compared with control and DFM1 diets (Table 1). Therefore, the hindgut digestibility of CP was greater (P < 0.005) in pigs fed DFM2 diet compared with the other 2 diets. The AID of total indispensable, total dispensable, and total AA was greater (P < 0.05) in the DFM1 diet compared with the control diet. There were no differences among diets in ATTD of GE, but the AID of GE was greater for the DFM1 diet than for the control and the DFM2 diets (P < 0.001). Therefore, the hindgut digestibility of GE was less (P < 0.05) in the DFM1 diet compared with the other diets. The DE on a DM basis for the DFM2 diet was greater (P < 0.05) compared with the control and the DFM1 diets.

 

Key points

  • Inclusion of Bacillus-based DFM in diets fed to pigs may increase the AID of AA and energy.
  • There are differences among sources of Bacillus spp. in their impact on AA and energy digestibility.

 

Table 1. Apparent total tract digestibility (ATTD) of CP and GE, apparent ileal digestibility (AID) of CP, AA, and GE, hindgut digestibility (HGD) of CP and GE, and concentrations of DE, ME in the control diet and in 2 diets containing direct fed microbials (DFM1 and DFM2), as-fed basis

 

Item

Control

DFM1

DFM2

SEM

P-value

ATTD CP, %

86.85

86.98

87.26

0.75

0.846

AID CP, %

74.94a

74.94a

71.86b

0.74

0.003

HGD CP, %

11.78b

11.97b

15.79a

1.41

0.004

Indispensable AA, %

    Arg

86.85b

87.98a

86.87b

0.67

0.026

    His

82.23

83.03

81.94

0.69

0.136

    Ile

77.18

78.95

77.84

0.67

0.055

    Leu

80.29b

82.10a

80.97ab

0.62

0.037

    Lys

75.81

76.46

75.31

1.90

0.250

    Met

81.54b

84.64a

81.76b

0.66

0.001

    Phe

79.57

80.27

79.17

0.73

0.269

    Thr

67.72b

71.15a

69.48ab

1.06

0.015

    Trp

78.36b

81.78a

79.07b

1.04

0.006

    Val

72.00b

74.63a

73.32ab

0.91

0.022

All indispensable AA, %

78.28b

80.04a

78.74ab

0.69

0.045

All dispensable AA, %

74.51b

77.29a

75.52ab

0.92

0.032

All AA, %

76.27b

78.56a

77.01ab

0.77

0.036

DE, diet, kcal/kg DM

3,609b

3,615b

3,696a

32

0.011

ME, diet, kcal/kg DM

3,480

3,498

3,545

29

0.068

ATTD GE, %

83.82

84.20

84.83

0.65

0.313

AID GE, %

64.97b

68.63a

66.38b

0.68

0.001

HGD GE, %

18.83a

14.56b

18.46a

0.91

0.002

a-bValues within a row lacking a common superscript letter are different (P ≤ 0.05).

This report is based on unpublished research by Laia Blavi and Hans H. Stein.

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