16th IFOAM Organic World Congress, Modena, Italy, June 16-20, 2008
Archived at http://orgprints.org/11787
Effects of silage or probiotics on performance and gut microbial
composition of organic growing-finishing pigs
Nagel, P.1, Domig, K. J.2, Hagmüller, W.3, Pfalz, S.2, Kronsteiner, S.2, Ortner, B.2,
Sundrum, A.4 & Zollitsch, W.1
Key words: organic, growing-finishing pigs, nutrition, performance, microbiota
Abstract
This paper will deal with the effects of the oral application of a probiotic preparation
(Bifidobacterium animalis) and of the provision of forage (maize and grass silage) to
growing-finishing pigs on the composition of the intestinal microbial population and
faecal microflora as an important determining factor for pork safety. 76 pigs were
reared in 4 different dietary treatments. Clinical health and immune status plus faeces
samples and samples of the gut content from the duodenum, ileum, caecum and colon
were collected from each animal. Since the second round of the feeding experiment
was only finished in March, the datasets are still incomplete because analyses are
ongoing, but preliminary results are already available. Microbial analysis showed that
CFU (per g DM of faeces) of bifidobacteria ranged from 2.6*10^8 (maize silage
treatment) to 8.7*10^8 (probiotic treatment). CFU counts of E.coli showed a
significantly lower amount for the control treatment (4.4*10^5) compared with the
grass silage- group (3.0*10^6). Blood analysis did not show significant differences
between treatments. Both the high level of animal performance (ADG between 902
and 929 g/d) and the negative clinical findings confirm the good health status of the
animals. Statistical analysis with the complete data set will soon show whether the
trends from these preliminary results will be confirmed for the overall experiment.
Introduction
Organic pork is placed as a premium product on the meat market. Besides the eating
quality, the nutrient content and other product quality traits, organic production also
has to guarantee a high level of food safety. Meat contaminated with pathogens will
potentially threaten public health (Leclerc et al., 2002). Pathogens may be introduced
into the pig production chain at several levels, reaching from the feed mill to the pork
distributors. Therefore, control measures must be applied on different levels if meat
safety is to be guaranteed (Lo Fo Wong et al., 2002). On the herd level, the
occurrence of pathogens in the intestines of growing-finishing pigs can be seen as one
potential starting point for further problems in the food chain. To avoid spreading of
potential pathogens via this path, organic production systems focus on improved
1 BOKU- University of Natural Resources and Applied Life Sciences Vienna, Department of
Sustainable Agricultural Systems Gregor Mendel Strasse 33, A-1180 Wien, Austria
2 BOKU- University of Natural Resources and Applied Life Sciences Vienna, Department of Food
Sciences and Technology, Gregor Mendel Strasse 33, A-1180 Wien, Austria
3 AREC- Agricultural Research and Education Centre Raumberg-Gumpenstein, Institute of
Organic Farming and Farm Animal Biodiversity, Austrasse 10, A-4600 Thalheim/Wels, Austria
4 University of Kassel, Department of Animal Nutrition and Animal Health, Nordbahnhofstrasse 1a,
D-37213 Witzenhausen, Germany
16th IFOAM Organic World Congress, Modena, Italy, June 16-20, 2008
Archived at http://orgprints.org/11787
housing conditions, high quality components in nutrition and animal health and
welfare. The concept of eubiosis seems to be a promising strategy for organic
livestock; this includes the maintenance of a stable microbial population in the
intestines which puts substantial competitive pressure on pathogens. Regulation
2092/91 (Council of the European Union, 1999) oblige organic farmers to provide
forage as a routine management measure for monogastric livestock. This practice
should lead to beneficial effects on animal health and welfare by maintaining
homeostatic conditions in the intestines. The occurrence of enteric pathogens may be
reduced due to the formation of organic acids and the growth of competing eubacteria
which utilize a variety of fibre components (non-starch carbohydrates,
oligosaccharides, cellulose etc. (Zentek, 1997; Brunsgaard, 1998; Stege et al., 2001)).
Basically, a stable eubacterial microflora exerts fundamental stimuli on the formation
of antibodies (Gebbers & Laissue, 1984; Alverdy et al., 1985).
Therefore in this study the effects of providing growing-finishing organic pigs with
either grass silage, maize silage or a probiotic preparation were tested on
performance, carcass quality and gut microbial composition.
Animals, materials and methods
The experiments were conducted at the experimental barn of the Institute of Organic
Farming and Farm Animal Biodiversity (HBLFA Raumberg-Gumpenstein) from August
2006 until March 2007. 76 pigs were assigned to 4 different dietary treatments in two
experimental rounds: control diet (ct), ct+grass silage, ct+maize silage, ct+probiotics.
All groups were feed restricted from 90 kg BW onwards to the end of the experiment
with a maximum daily feed provision of 2.7 kg of compound feed.
Each group (4 - 5 animals) was offered two to three kilograms of silage every morning.
In case the total amount of silage was consumed by one group, the amount offered
was increased. Before giving the fresh silage, the leftovers from the day before was
weighed back in order to record the estimated amount that disappeared. Additionally,
the n-alkane method (Mayes et al., 1986) was used three times per trial to estimate
the forage intake. The probiotic group received a probiotic preparation
(Bifidobacterium animalis subsp. lactis Ra 18, developed at the University of Bologna)
fed daily together with the compound feed. Every pig in the probiotic group was
planned to receive about 200 millions of bifidobacteria per day.
Results and discussion
Since the datasets are still incomplete due to ongoing analyses, preliminary results
are presented herein. In Table 1 the faecal microbial composition is given for the
experimental treatments.
Tab. 1: Microbial composition of faeces (CFU/ g DM)
treatment
n
control
probiotics
maize silage
grass silage
19
19
19
19
Clostridium sp.
p = 0.030
1.19*10^8ab
1.09*10^8ab
8.10*10^7a
1.57*10^8b
Bifidobacteria sp.
p < 0.001
5.95*10^8a
9.04*10^8c
3.49*10^8b
5.03*10^8ab
E. coli
p = 0.059
3.74*10^5ab
1.70*10^5a
7.48*10^5b
6.43*10^5ab
16th IFOAM Organic World Congress, Modena, Italy, June 16-20, 2008
Archived at http://orgprints.org/11787
The only significant differences concerning the microbial composition so far detected
are shown in Since the datasets are still incomplete due to ongoing analyses,
preliminary results are presented herein. In Table 1 the faecal microbial composition is
given for the experimental treatments.
Tab. 1. In general the number of Colony forming Units (CFU) per g faeces was high,
indicating a well established microbial community in the gastro intestinal tract. Some
of the differences between treatments were significant but in microbiological terms too
small to conclude a relevant effect. Realtime-PCR showed only 4 positive results in
different groups and over the two experimental rounds. In the first round three
samples at the slaughterhouse showed the presence of Lawsonia intracellularis (2
pigs from the grass silage treatment and 1 from the probiotic treatment) and in the
second round one of the faeces samples contained Lawsonia intracellularis (grass
silage treatment). Blood analysis did not show significant differences between
treatments.
Tab. 2: Animal performance
treatment
n
control
probiotics
maize silage
grass silage
19
19
19
19
daily weight gain
p = 0.634
902 g/d
929 g/d
916 g/d
903 g/d
carcass
p = 0.215
79.01 %
79.39 %
79.09 %
79.61 %
lean meat
p = 0.093
58.52 %
57.84 %
59.64 %
58.74 %
pH
p = 0.003
6.41ab
6.39ab
6.26b
6.48a
Both the high performance level (see The only significant differences concerning the
microbial composition so far detected are shown in Since the datasets are still
incomplete due to ongoing analyses, preliminary results are presented herein. In
Table 1 the faecal microbial composition is given for the experimental treatments.
Tab. 1. In general the number of Colony forming Units (CFU) per g faeces was high,
indicating a well established microbial community in the gastro intestinal tract. Some
of the differences between treatments were significant but in microbiological terms too
small to conclude a relevant effect. Realtime-PCR showed only 4 positive results in
different groups and over the two experimental rounds. In the first round three
samples at the slaughterhouse showed the presence of Lawsonia intracellularis (2
pigs from the grass silage treatment and 1 from the probiotic treatment) and in the
second round one of the faeces samples contained Lawsonia intracellularis (grass
silage treatment). Blood analysis did not show significant differences between
treatments.
Tab. 2) and the negative clinical findings confirm the good health status of the
animals. Preliminary results for forage intake using the n-Alkane method (Mayes et al.,
1986) from the first sampling period (1st experimental round) showed that all animals
consumed certain amounts of forage. The control and probiotic group consumed only
straw (from the straw bedding) and the grass and maize silage group a mixture of
straw and silage. The relation of straw and silage is unknown but intake of grass and
maize silage was observed for both silage groups.
Tab. 3: Estimated forage intake using the n-Alkane method (Mayes et al., 1986)
and weight difference
treatment
n-Alkane method
weighing trough feeder
16th IFOAM Organic World Congress, Modena, Italy, June 16-20, 2008
Archived at http://orgprints.org/11787
(g as fed /d & pen)
control
(g as fed /d & pen)
299
probiotics
234
maize silage
1503
450
grass silage
588
465
Obtaining reliable results from daily weighing of the trough feeder was sometimes
difficult. All of the animals showed distinct explorative behaviour using silage as
substrate; due to its structure and other factors, maize silage was obviously more
attractive for pigs than grass silage. Obvious losses had to be replenished without
adding too much straw or other organic material from the area around the trough
feeder. After the n-Alkane analysis is completed, the results will help to correctly
interpret the results derived by weighing and to estimate the overall forage intake
(Table 3)..
However, the stimulating effect of fibre components on the gut microbiota should be
granted even if the lactic acid bacteria do not survive the stomach passage. Additional
effects can be expected from the formation of organic acids which help create a
hostile environment for enteric pathogens in the gut (Zentek, 1997; Brunsgaard, 1998;
Stege et al., 2001). From the data available so far it can be concluded that
supplementing organic growing-finishing pigs with maize silage, grasssilage or a
probiotic preparation consisting of a certain strain of Bifidobacteria sp. does not
significantly affect performance and carcass traits. Effects on the microbial
composition of faeces may be too small to be of practical relevance and need to be
confirmed by analysis of digesta samples from different positions of the intestinal tract.
Acknowledgments
The authors gratefully acknowledge funding from the European Community financial
participation under the Sixth Framework Programme for Research, Technological
Development and Demonstration Activities, for the Integrated Project
QUALITYLOWINPUTFOOD, FP6-FOOD-CT-2003- 506358. The views expressed are
those of the authors, not of the commission.
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16th IFOAM Organic World Congress, Modena, Italy, June 16-20, 2008
Archived at http://orgprints.org/11787
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