A Comparative Analysis of the Fecal Bacterial Communities of Light and Heavy Finishing Barrows Raised in a Commercial Swine Production Environment

Abstract

For commercial swine producers, the natural variation in body weight amongst pigs in a herd presents a challenge in meeting the standards of meat processors who incentivize target carcass weights by offering more favorable purchase prices. Body weight variation in a swine herd is evident as early as birth, and it is typically maintained throughout the entire production cycle. Amongst the various factors that can affect growth performance, the gut microbiome has emerged as an important factor that can affect efficiency, as it contributes to vital functions such as providing assimilable nutrients from feed ingredients that are inedible to the host, as well as resistance to infection by a pathogen. In this context, the objective of the study described in this report was to compare the fecal microbiomes of light and heavy barrows (castrated male finishing pigs) that were part of the same research herd that was raised under commercial conditions. Using high-throughput sequencing of amplicons generated from the V1-V3 regions of the 16S rRNA gene, two abundant candidate bacterial species identified as operational taxonomic units (OTUs), Ssd-1085 and Ssd-1144, were found to be in higher abundance in the light barrows group. Ssd-1085 was predicted to be a potential strain of Clostridium jeddahitimonense, a bacterial species capable of utilizing tagatose, a monosaccharide known to act as a prebiotic that can enhance the proliferation of beneficial microorganisms while inhibiting the growth of bacterial pathogens. OTU Ssd-1144 was identified as a candidate strain of C. beijerinckii, which would be expected to function as a starch utilizing symbiont in the swine gut. While it remains to be determined why putative strains of these beneficial bacterial species would be in higher abundance in lower weight pigs, their overall high levels in finishing pigs could be the result of including ingredients such as corn and soybean-based products in swine diets. Another contribution from this study was the determination that these two OTUs, along with five others that were also abundant in the fecal bacterial communities of the barrows that were analyzed, had been previously identified in weaned pigs, suggesting that these OTUs can become established as early as the nursery phase.

Modulation of Porcine Gut Microbiota and Microbiome: Hologenomic, Dietary, and Endogenous Factors

“…Fowler et al [ 10 ] investigated the fecal microbiome origins of the large variability in final body weight (BW) of the later finishing swine under a typical US commercial swine production and research facility setting. Their pigs had the same genetic background, were fed the same commercial swine diets, and did not differ between the barrows and the gilts in growth rates and the final market BW [ 10 ]. However, while the pen’s mean final BW averaged 133 kg, the heavy final BW group (146 kg) finishers were heavier than the light final BW group (120 kg) by 22% [ 10 ].…”

“…Their pigs had the same genetic background, were fed the same commercial swine diets, and did not differ between the barrows and the gilts in growth rates and the final market BW [ 10 ]. However, while the pen’s mean final BW averaged 133 kg, the heavy final BW group (146 kg) finishers were heavier than the light final BW group (120 kg) by 22% [ 10 ]. This large variation in final market BW within the same finisher herd not only limits the swine production profit margin but also reduces feed and nutrient utilization efficiency with negative impacts on the environment.…”

“…Clearly, viewing and approaching the host–microbiome ecosystem as a holobiont at the hologenomic level would help decipher this complexity [ 12 , 13 , 14 , 15 ]. Fowler et al [ 10 ] approached this applied swine production issue in the large variability in final BW of the finisher swine via metagenomics. They subsequently carried out a combined total of 757,687 high-quality sequence reads from the V1–V3 partial region of the 16S rRNA genes generated from all the fecal samples of the light (final BW range of 113–129 kg, n = 21) and heavy (final BW weight range of 137–156 kg; n = 23) pigs [ 10 ].…”

“…Fowler et al [ 10 ] approached this applied swine production issue in the large variability in final BW of the finisher swine via metagenomics. They subsequently carried out a combined total of 757,687 high-quality sequence reads from the V1–V3 partial region of the 16S rRNA genes generated from all the fecal samples of the light (final BW range of 113–129 kg, n = 21) and heavy (final BW weight range of 137–156 kg; n = 23) pigs [ 10 ]. Alpha-diversity endpoints were assessed by richness (Chao1, ACE) and diversity (Shannon, Simpson) that were calculated via the obtained operational taxonomic units (OTUs) [ 10 ].…”

“…They subsequently carried out a combined total of 757,687 high-quality sequence reads from the V1–V3 partial region of the 16S rRNA genes generated from all the fecal samples of the light (final BW range of 113–129 kg, n = 21) and heavy (final BW weight range of 137–156 kg; n = 23) pigs [ 10 ]. Alpha-diversity endpoints were assessed by richness (Chao1, ACE) and diversity (Shannon, Simpson) that were calculated via the obtained operational taxonomic units (OTUs) [ 10 ]. Comparisons of the fecal bacterial communities between the light and the heavy barrows were also conducted using principal coordinate analysis (PCoA) of these OTU data [ 10 ].…”