Plant extracts may be beneficial to pig health

Plant extracts may be beneficial to pig health

*John H. Goihl is president of Agri-Nutrition Services Inc., Shakopee, Minn. To expedite answers to questions concerning this article, please direct inquiries to Feedstuffs, Bottom Line of Nutrition, 7900 International Dr., Suite 650, Bloomington, Minn. 55425, or email [email protected]

PLANT extracts are being proposed as alternatives for antibiotics because of their significant antimicrobial effects.

Plant extracts are secondary plant metabolites that can be naturally obtained from plant materials or chemically synthesized.

Previous research from feeding plant extracts offers the following potential mechanisms that may be involved in reducing diarrhea in piglets infected with Escherichia coli:

* Plant extracts may directly affect the activity of pathogenic E. coli by killing or inhibiting bacterial proliferation or toxin secretion.

* Plant extracts may improve gut health by strengthening gut barrier function, resulting in some protection against bacteria and/or their toxins.

* Plant extracts may enhance the gastrointestinal immune system and/or the systemic immune system, which indirectly improves pig health and reduces diarrhea in pigs.

Several studies have reported that the supplementation of different plant extracts improved growth performance and gut health or reduced disease incidences of weaned pigs, but other studies have reported no beneficial effects.

Postweaning diarrhea due to E. coli is an important cause of death in weaned piglets. It results in mortality, morbidity, decreased performance and increased medication costs.

Swine researchers Y. Liu, M. Song, T.M. Che, J.A.S. Almeida, J.J. Lee, C.W. Maddox and J.E. Pettigrew at the University of Illinois and D. Bravo of Pancosma S.A. conducted a study to evaluate the effects of three different plant extracts on diarrhea, immune response, intestinal morphology and growth performance of weaned pigs experimentally infected with pathogenic F-18 E. coli.

The sows and pigs used in this experiment did not receive E. coli vaccines, antibiotic injections or antibiotics in creep feed. Spray-dried plasma, antibiotics and zinc oxide were not included in the basal postweaning diet.

Sixty-four weaned pigs (equal numbers of barrows and gilts) at 21 days of age were selected for the study. After weaning, all pigs were moved to disease containment chambers and were randomly assigned to treatments. Pigs were housed in individual pens for 15 days (four days before and 11 days after the first E. coli challenge). Piglets had ad libitum access to feed and water.

The study used four dietary treatments with or without E. coli challenge for a total of eight treatments, with eight replicates per treatment.

In the E. coli challenge treatments, all pigs were inoculated orally with 3 mL of F-18 E. coli per day for three consecutive days. In the unchallenged treatments, pigs were inoculated for three consecutive days with 3 mL of phosphate-buffered saline per day as the control.

The basal postweaning diet was a fortified complex diet containing 15% dried whey, 10% fish meal, 10% lactose, 5% soybean meal concentrate, 10% soybean meal and 41.5% corn.

The four dietary treatments were: (1) control, (2) 10 parts per million of capsicum, (3) 10 ppm of garlic botanical and (4) 10 ppm of turmeric oleoresin.

Before weaning, feces from sows and all the piglets destined for this experiment were collected and verified to be free of detectable beta-hemolytic E. coli.

During the experiment, clinical observations, diarrhea scores and alertness scores were recorded daily. The diarrhea score of each pig was assessed using a scouring system ranging from one (normal) to five (watery diarrhea). The alertness score of each pig was assessed visually with a scoring system from one (normal) to three (severely depressed/recumbent).

After inoculation, fecal samples were collected from each pig on days 0, 3, 5, 8 and 11 post-infection. Blood samples were collected from the jugular vein of each pig before E. coli challenge on day 0 and days 5 and 11 post-infection. The pigs and feeders were weighed on the day of weaning and days 5 and 11 post-infection in order to calculate the growth performance criteria.

Half of the pigs were euthanized on day 5 post-infection and the remainder on day 11 post-infection. Three 3 cm segments from the middle of the jejunum, the ileum and the middle of the colon were collected for histological analysis.

 

Results

The Table summarizes the effect of the four treatments on growth performance, diarrhea score, frequency and white and red blood cell counts.

The researchers provided the following interpretations of their results:

* Before the E. coli infection, the three dietary plant extract treatments did not affect pig performance in the E. coli infected group compared to the control pigs.

* Pigs challenged by E. coli had decreased bodyweight, average daily gain and gain:feed from day 0 to day 5 and from day 0 to day 11 post-injection.

* Pigs fed the three dietary plant extract treatments in the control group grew faster than the control pigs during the early part of the experiment and tended to grow more slowly later, resulting in no dietary effects over the entire period. There were no differences among the three plant extract treatments in the control group.

* The E. coli-challenged pigs had increased diarrhea scores and overall frequency of diarrhea from day 3 to day 11 post-injection.

* The three plant extract treatments in the E. coli-challenged pigs resulted in reduced diarrhea scores and frequency of diarrhea from day 3 to day 11 post-injection.

* The E. coli-challenged pigs tended to have increased total white blood cells on day 5 and increased on day 11 post-injection compared to the control group. However, the three plant extract treatments in the E. coli-challenged group resulted in decreased white blood cell counts.

There were no differences among the three plant extract treatments. The results indicate that feeding plant extracts to weaned pigs challenged with F-18 E. coli reduced diarrhea and inflammation by improving gut health, as evidenced by increased villus height of the small intestine. These findings are in agreement with previous data.

The reduced incidence of diarrhea indicates that many plant extracts have antidiarrheal activity by inhibiting gastrointestinal motility and stimulating water absorption.

In this study, low doses of plant extracts were used to test how feeding plant extracts affected the immune response of pigs challenged by E. coli. The results indicate that even low levels of plant extracts may not have antimicrobial activity but may have beneficial effects on pig health, probably by regulation of the immune system.

Feeding dietary plant extracts may alleviate the overstimulation of the systemic immunity and early immune response of pigs infected with E. coli.

 

The Bottom Line

The results of this experiment indicate that a low level of the three dietary plant extracts tested can be used in pig diets to improve pig health compared to controls by alleviating postweaning diarrhea.

 

Reference

J. Anim. Sci. Vol. 91; No. 11.

 

Experimental results

 

-Control-

-Infected with E. coli-

Criteria

1

2

3

4

1

2

3

4

Bodyweight, kg

Day 0

6.66

6.46

6.63

6.66

6.51

6.59

6.43

6.63

Day 5

6.93

7.11

7.15

7.24

6.54

6.68

6.53

6.77

Day 11

9.58

8.93

8.60

9.08

8.13

8.18

8.35

9.20

Growth performance, days 0-11

Avg. daily gain, g

276

251

212

246

149

157

182

218

Avg. daily feed intake, g

540

512

596

421

615

568

561

545

Gain:feed

0.53

0.50

0.38

0.61

0.25

0.31

0.34

0.40

Diarrhea score*

Days 0-2

1.96

1.17

1.21

1.29

1.93

1.67

1.35

1.36

Days 3-5

2.06

1.35

1.45

1.67

3.43

2.50

2.13

2.00

Days 6-8

1.44

1.18

1.17

1.21

2.86

2.58

2.83

2.90

Days 8-11

1.09

1.04

1.08

1.00

3.51

2.13

1.21

1.15

Diarrhea frequency**

20

4

7

9

40

26

17

16

White blood cells, 103/microliter

Day 5

15.2

14.5

17.0

13.8

21.1

14.5

14.6

18.3

Day 11

16.7

15.8

19.0

14.4

32.2

21.6

23.0

24.3

Red blood cells, 106/microliter

Day 5

6.74

6.74

7.06

6.70

7.23

6.64

6.90

6.89

Day 11

5.90

5.79

6.35

6.35

7.12

6.10

6.11

6.26

*1 = normal, 2 = moist feces, 3 = mild diarrhea, 4 = severe diarrhea, 5 = watery diarrhea.

**Number of pigs with diarrhea scores of 3 or greater.

 

Volume:85 Issue:52

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