Lactation Stage-Dependency of the Sow Milk Microbiota.

Wei Chen,Ruiting Wu,Jingyun Ma,Jinming Gao,Tian Lan,Ning Lv,Jiandui Mi,Jian Cheng,Xindi Liao

doi:10.3389/fmicb.2018.00945

Abstract

Breast milk is essential for the initial development of neonatal animals, as it provides not only essential nutrients and a broad range of bioactive compounds but also commensal bacteria. The milk microbiota contributes to the “initial” intestinal microbiota of infants and also plays a crucial role in modulating and influencing neonatal health. However, the milk microbiota of sows has yet to be systematically investigated. The goal of the present study was to characterize variations in bacterial diversity and composition in sow milk over the duration of lactation using a high-throughput sequencing approach. Milk samples (n = 160) were collected from 20 healthy sows at eight different time points, and microbial profiles were analyzed by 16S ribosomal RNA (rRNA) sequencing using the Illumina MiSeq platform. The composition and diversity of the milk microbiota changed significantly in colostrum but was relatively stable in transitional and mature milk. Firmicutes and Proteobacteria were the most dominant phyla in sow milk. The relative abundances of the two most dominant bacterial genera, Corynebacterium and Streptococcus, were significantly higher in colostrum than in transitional milk and mature milk samples, and the other four most dominant bacterial taxa (Lactobacillus, two unclassified genera in the families Ruminococcaceae and Lachnospiraceae, and an unclassified genus in the order Clostridiales) demonstrated higher relative abundances in transitional and mature milk than in colostrum. Membrane transport, amino acid metabolism and carbohydrate metabolism were the most abundant functional categories in sow milk communities. Microbial network analysis based on the predominant genera revealed that the abundance of Helcococcus was negatively correlated with the abundances of most other genera in sow milk. Our results are the first to systematically indicate that the sow milk microbiota is a dynamic ecosystem in which changes mainly occur in the colostrum and remain generally stable throughout lactation.

Highlights

Breast milk is the most important postpartum element during the initial development of neonates because it provides optimal nutrition, bioactive components, and host defense proteins to suit all needs of the developing neonate in an age-adapted manner (Walker, 2010; Ballard and Morrow, 2013)
The principal coordinate analysis (PCoA) plots show that the bacterial community profiles clustered more closely to each other in transitional and mature milk samples than in colostrum samples (Figures 1D–F)
Alpha and beta diversity analyses indicated that lactation stage plays crucial roles in shaping the composition of the sow milk microbiota

Summary

Introduction

Breast milk is the most important postpartum element during the initial development of neonates because it provides optimal nutrition, bioactive components, and host defense proteins to suit all needs of the developing neonate in an age-adapted manner (Walker, 2010; Ballard and Morrow, 2013). Microbial Diversity in Sow Milk bacteria that are able to act as pioneer bacteria during the critical stage of initial neonatal gut colonization (Fernandez et al, 2013; Li et al, 2017). Many of these commensal bacteria in milk play active roles in reducing the incidence and severity of infections (Martín et al, 2005; Olivares et al, 2006a), modulating early immune system development, reducing the risk of immune inflammatory or metabolic diseases (Olivares et al, 2006b; DiazRopero et al, 2007), and determining metabolism in the infant (Maldonado et al, 2010; Gil-Campos et al, 2012). Using pyrosequencing to investigate the DNA encoding the V1–V3 hypervariable regions of bacterial 16S rRNA, Cabrera-Rubio et al (2012) found that Leuconostoc, Weissella, Lactococcus, and Staphylococcus were predominant in mature milk produced by women living in Finland, while Streptococcus was more relatively abundant in colostrum. Boix-Amoros et al (2016) used similar methods and found that the most common genera in the colostrum of Spanish mothers were Staphylococcus and Acinetobacter, while Pseudomonas and Streptococcus were most common in transitional milk and Acinetobacter was most common in mature milk samples

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