Housing systems and their influence on porcine intestinal microbiota

Housing systems present themselves in different types within pig production, and they are used to different extents. However, little is known about their effect on the composition of intestinal microbiota.

A correct colonization of the intestinal tract, especially during the initial phases of life is fundamental for any individual. The quality of this colonization to some extent, will determine the onset of digestive disorders during the first weeks of life and can even affect intestinal homeostasis on the long term.

Gut microbiota plays an important role in the host’s health:

Colonization of the intestinal tract of piglets begins at the time of birth by the microbiota present in thematernal genital and intestinal tract. Soon after, this colonization is complemented by the microbiota present in the environment.

Depending on management and production conditions, the importance of maternal and environmental microbiota sources varies considerably. In the case of pig production, cleaning procedures carried out before sows enter the maternity ward substantially reduce the presence of environmental microbiota.

Despite this, it is difficult to predict to what extent are sows responsible for the gut microbiota that piglets develop:

⇒A study showed that the administration of probiotics to sows during gestation affects the composition of piglets’ microbiota, suggesting that a maternal influence exists.

⇒ On the other hand, a greater similarity has been found in the microbiota of piglets housed in the same pen compared to that of piglets housed separately. Which implies that there is an environmental effect.

Currently, pig production systems offer different environmental conditions, varying from conventional systems to ecological systems.

However, when comparing the microbiota composition of pigs raised in both systems, no significant differences were observed.

Similarly, no major differences have been found when comparing the microbiota of pigs housed indoors with that of pigs housed outdoors.

When it comes to gestation rooms, the most commonly used system is slat pens. However, the use of straw-enriched systems on the ground is becoming more popular.

⇒  In enriched systems, a decrease in stress levels and the consumption of straw containing non-digestible fiber could have an impact on gut microbiota.

Along with the previous studies, an evaluation was made to determine if the type of housing used in gestation influences the development of piglets’ intestinal microbiota during the first day of life.

» EXPERIMENTAL DESIGN

In order to determine how the type of housing in gestation influences the composition of sows’ intestinal microbiota, two study groups were formed consisting of Large-White x Landrace sows subjected to the same management system but housed in different types of pens during gestation.

At day 105 of gestation, all sows were transferred to identical calving cages and a slat floor.

The study was replicated three times (April 2014, September, 2014 and January 2015), taking fecal samples from sows at the time of calving and from piglets 1 and 4 days old (A total of 139 fecal samples was collected).

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»  RESULTS

⇒ The composition of fecal microbiota varies with age

When comparing the fecal microbiota of sows, 1-day-old piglets and 4-day-old piglets, it was observed that:

→ 36 different genera were found in at least 90% of the sows.

→Abundance and diversity of the microbiota increases with age (1-day-old piglets < 4-day-old piglets < adult sows) 

50% – Adult sows: Prevotella and Oscillospira were the predominant genera, composing almost 50% of sows’ total fecal microbial population at the time of calving.

50% – 1-day-old piglets: The predominant genus in 1-day-old piglets was E. coli (more than 50% of the total microbiota) which, together with Clostridium, Fusobacterium and Actinobacillus, constituted more than 80% of the microbial population.

60% – 4-day-old piglets: The predominant genera in 4-day-old piglets were Bacteroides, Fusobacterium and Prevotella, which constituted 60% of the total microbiota.

⇒ The composition of microbiota varies depending on the housing system of gestating sows.

When comparing the fecal microbiota of the two groups of sows (conventional pens and enriched pens), differences were observed in relation to the abundance of 13 microbial genera:

→ 6 genera were more abundant in sows housed in conventional pens, all belonging to the phylum Firmicutes.

→7 genera were more abundant in sows housed in enriched pens. Most of them belonging to the phylum Bacteroidetes and Fibrobacter.

The microbiota of sows housed in the enriched systems contained a significantly higher amount of Prevotella, Parabacteroides, CF231, Phascolarctobacterium, Fibrobacter, Anaerovibrio and YRC22. With significantly less presence of Lactobacillus, Bulleidia, Lachnospira, Dorea, Ruminococcus and Oscillospira compared to the microbiota from sows housed in the conventional system.

The analysis of the fecal microbiota of sows and their piglets shed light on the dynamics of intestinal colonization and how environmental conditions can influence their composition.

Although E. coli is typically the first intestinal colonizer, in the case of 1-day-old piglets a predominance of Escherichia, Clostridium, Fusobacterium and Actinobacillus was found.

⇒ However, the presence of Actinobacillus and Fusobacterium in pigs’ palatal tonsils has been demonstrated, with little replication at the intestinal tract level. This could explain their presence in pigs’ feces.

In 4 days old piglets, Bacteroides replaced E. coli as the most abundant member. This is a surprising fact considering that Bacteroides is rare in adult pigs, where Prevotella predominates within the phylum Bacteroidetes.

⇒The transient occurrence of Bacteroides in piglets is unclear, but could be related to lactation, weaning, and changes in gene expression.

⇒ Members of the Phylum Bacteroidetes are known  to inhabit within the mucus covering intestinal epithelial cells and whose structure and composition varies throughout the intestinal tract and possibly with age.

Large differences in microbiota composition of sows and piglets mean that mothers are not the only source of colonization during the first days of life.

In fact, factors such as lactation and the environment(housing systems) seem to have greater importance when it comes to the intestinal colonization of piglets.

→ However, other sources of microbiota (skin surface, vagina, milk) cannot be ignored, and it must be considered that the role of the sow as a microbiota donor increases as weaning approaches and that it can be influenced by the genetic characteristics of each sow and piglet.

→ On the other hand, variations in sows’ intestinal microbiota suggest that housing systems influence intestinal microbiota composition, probably due to the ingestion of straw.

The phylum Bacteroidetes and Fibrobacter, which had greater representation in sows housed in enriched systems, are characterized by their ability to metabolize insoluble polysaccharides (cellulose, hemicellulose or pectins). Thus, pens enriched with straw would exert a positive selection on the members of the phylum Bacteroidetes and Fibrobacter.

It is concluded that the housing of sows in enriched systems with strar favors a slightly positive selection towards the phylum Bacteriodetes and Fibrobacter, although these differences are not reflected in the composition of their piglet’s microbiota.

Differences in the diet composition of piglets are likely to delay intestinal colonization by the microbiota of adult sows. Therefore, it should not be forgotten that mothers continue to influence the development of their offspring’s microbiota until weaning.

Authors:

Tereza Kubasova1 , Lenka Davidova-Gerzova1 , Elodie Merlot2 , Matej Medvecky1 , Ondrej Polansky1 , Delphine Gardan-Salmon3 , Helene Quesnel2 & Ivan Rychlik1

1Veterinary Research Institute, Czech Republic

²INRA, France

³CCPA Group, France

Modified from Kubasova, T., Davidova-Gerzova, L., Merlot, E., Medvecky, M., Polansky, O., & GardanSalmon, D. et al. (2017). Housing Systems Influence Gut Microbiota Composition of Sows but Not of Their Piglets. PLOS ONE, 12(1), e0170051. doi: 10.1371/ journal.pone.0170051 [/register]