The Maternal Milk Microbiome in Mammals of Different Types and Its Potential Role in the Neonatal Gut Microbiota Composition

Maternal milk, a main source of nutrition for neonates in early life, has attracted attention. An increasing number of studies have found that maternal milk has a high microbial diversity, as well as factors that might influence this diversity. However, there is a lack of knowledge regarding the effects of host diet and phylogeny on maternal milk microbes and the contribution of the maternal milk microbiota to the neonatal gut microbiota. Here, we analyzed the maternal milk and fecal microbiota of nine species (lion, dog, panda, human, mouse, rhesus macaque, cow, goat, and rabbit) of mammals of three type groups (herbivore, omnivore, and carnivore) using 16S rRNA amplicon sequencing. Our study provided evidence of host diet and phylogeny on the maternal milk microbiota. Moreover, functional prediction revealed that the carnivores had a significantly higher percentage of base excision repair, glycerolipid metabolism, taurine and hypotaurine metabolism, inorganic ion transport and metabolism, and nucleotide metabolism; while arginine and proline metabolism showed enrichment in the herbivore group. Source-tracking analysis showed that the contributions of bacteria from maternal milk to the microbiota of neonates of different mammals were different at day 3 after neonatal birth. Overall, our findings provided a theoretical basis for the maternal milk microbiota to affect neonatal fecal microbiota at day 3 after neonatal birth.

Effect of Dams and Suckling Lamb Feeding Systems on the Fatty Acid Composition of Suckling Lamb Meat

The effects of the dams and suckling lamb feeding systems on the fatty acid (FA) profile of lamb meat are reviewed in this article. The suckling lamb can be considered a functional monogastric, and therefore, its meat FA composition is strongly influenced by the FA composition of maternal milk. The major source of variation for ewe milk FA composition is represented by pasture amount and type. In the traditional sheep breeding system of the Mediterranean area, the main lambing period occurs in late autumn–early winter, and ewes are able to exploit the seasonal availability of the natural pastures at their best. Therefore, lambs start suckling when maternal milk concentrations of vaccenic, rumenic, and n-3 long-chain polyunsaturated FA in maternal milk are the highest. When maternal diet is mainly based on hay and concentrates, the use of vegetable oils can be considered a good strategy to improve the meat FA profile of suckling lambs.

Antioxidant Potential of Pediococcus Pentosaceus Strains from the Sow Milk Bacterial Collection in Weaned Piglets

Background: In modern animal husbandry, breeders pay increasing attention to improving sow nutrition during pregnancy and lactation to favor the health of neonates. Sow milk is a main food for piglets during their first three weeks of life, which is not only a rich repository of essential nutrients and a broad range of bioactive compounds, but also an indispensable source of commensal bacteria. Maternal milk microorganisms are important sources of commensal bacteria for neonatal gut. Bacteria from maternal milk may serve as an additive to confer a health benefit on the composition of the indigenous microbiota of piglets. Methods: The sow milk microbiota was collected using the culturomics methods of Continuous Culture and Interval Sampling, following by the identification of 16S rDNA gene sequences. To screen potential probiotics, the functional evaluation was conducted to assess their antagonistic activity against pathogens in vitro and evaluate their resistance against oxidative stress in damaged Drosophila induced by paraquat. In piglet feeding trial, a total of 54 newborn suckling piglets were chosen from nine sows and randomly assigned to three treatments with different concentration of a candidate strain. Multiple approaches were carried out to verify its antioxidant function including western blotting, enzyme activity analysis, metabolomics and 16S rDNA sequencing. Results: The 1240 isolates were screened out from the sow milk microbiota and grouped into 271 bacterial taxa based on a nonredundant set of 16S rDNA gene sequences. Among 80 Pediococcus isolates, a new Pediococcus pentosaceus strain (SMM914) showed best performance in inhibition ability against swine pathogens and in Drosophila model challenged by paraquat. Pretreatment of piglets with SMM914 induces the Nrf2-Keap1 antioxidant signaling pathway and greatly affected the pathways of amino acid metabolism and lipid metabolism in plasma. In colon, Lactobacillus was significantly increased in the high dose of SMM914 group compared with the control group. Conclusion: SMM914 functions as a promising probiotic conferring antioxidant capacity by activating the Nrf2-Keap1 antioxidant signaling pathway in piglets. Our study provided useful resources for deeply understanding the relationships between the maternal microbiota and offspring.

Impact of IgG isotype on the induction of antibody-dependent cellular phagocytosis of HIV by human milk leukocytes

Approximately 100,000 mother-to-child transmission (MTCT) events of HIV via human milk feeding occur each year (1). However, only about 15% of infants milk-fed by untreated HIV+ mothers become infected, suggesting a protective effect of the milk itself (1, 2). Infants ingest 105-108 maternal leukocytes daily via milk, which remain functional beyond ingestion (3-9). Such function may be elicited by maternal milk antibody (Ab). Though IgA is dominant in milk, most HIV-specific milk Abs are of the IgG subclass, highlighting the importance of investigating the function of each IgG isotype in the milk context (10-16). Though Ab effector function mediated by the constant (Fc) domain via interaction with Fc Receptors (FcRs), such as Ab-dependent cellular phagocytosis (ADCP), are critical in protecting against HIV infection, ADCP is largely unexplored as it relates to mitigation of MTCT (17-21). Presently we report the ADCP activity of milk leukocytes against HIV particles and immune complexes (ICs), using 57 unique samples from 34 women, elicited by IgG1/2/3/4 of monoclonal (m)Ab 246-D. Granulocyte ADCP of HIV was most potent compared to other phagocytes when elicited by IgG1/3/4. IgG1/3 activated granulocytes similarly, exhibiting 1.6x-4.4x greater activity compared to IgG2/4, and a preference for virus compared to ICs. Notably, CD16- monocyte ADCP of a given target were unaffected by isotype, and CD16+ monocytes were poorly stimulated by IgG1. IgG2/4 elicited potent IC ADCP, and in terms of total leukocyte IC ADCP, IgG4 and IgG3 exhibited similar function, with IgG4 eliciting 1.6x-2.1x greater activity compared to IgG1/IgG2, and CD16+ monocytes most stimulated by IgG2. These data contribute to a more comprehensive understanding of Fc-mediated functionality of milk leukocytes, which is critical in order to develop therapeutic approaches to eliminating this route of MTCT, including mucosal administration of mAbs and/or a maternal vaccination aimed to elicit a potent milk Ab response.

PSII-19 The Effects of Maternal Programming on Dairy Bull Calf Response to an Intravenous Glucose Tolerance Test

Calves are prone to health issues with high mortality observed during the first 3 weeks of life. We hypothesized that dam milk production levels and/or mastitis infection during gestation will lead to reduced insulin production and increased circulating glucose concentration in response to an Intravenous Glucose Tolerance Test (IVGTT) in young dairy bull calves. Calves (n = 45) were selected from dams classified has high producers (HI; Top 25% for herd M305; n = 7), high producers with high somatic cell count (SCC; HIMAST; SCC test during gestation over 200,000 cells/mL; n = 15), moderate producers (MOD; lower 60% for herd M305; n =17) or moderate producers with high SCC (MODMAST; n = 6). IVGTT were performed on the calves at 7 weeks of age. Blood samples were collected prior to (-30, -15 and 0 min) infusion of glucose. After glucose (0.15 grams /kg bw) administration, samples were collected at 2, 5, 10, 15, 30, 60, and 120-minutes post infusion. Serum insulin and glucose concentrations were determined at Cornell Veterinary Medical Diagnostic Laboratory (Ithica, NY). Data were analysed in SAS using Proc Mixed. Insulin:glucose ratio was analysed using Proc Mixed with repeated measures for treatment x time. No effect of maternal milk production and/or mastitis infection during gestation was observed on calf baseline insulin, insulin AUC, baseline glucose or glucose AUC (P ≥ 0.12). Similarly, no difference in Insulin:Glucose ratio was observed in these calves (P = 0.66). In conclusion, high maternal milk production and/or mastitis infection may not have an effect on circulating insulin production in calves in response to an IVGTT. Correlation analyses will be performed on these data, as well as additional analyses, to determine if insulin sensitivity or response (ie: phase 1 response) was altered further.

COVID-19 and breastfeeding: can SARS-CoV-2 be spread through lactation?

SARS-CoV-2 is a new betacoronavirus that was first reported in the Hubei province, China, in December 2019. The virus is likely transmitted through air droplets. However, there are reported cases where SARS-CoV-2-RNA was found in other samples, such as blood or stool. Nonetheless, there is limited information concerning the presence of viral RNA in pregnancy-related samples, specifically breast milk. However unlikely, there is still uncertainty regarding the possibility of vertical transmission from mother to infant through breastfeeding. This review aims to synthetize the literature written so far on this topic. Despite not being extensively researched, vertical transmission through breast milk seems unlikely. Case series showed that milk samples from mothers with COVID-19 were almost entirely negative. So far, there have been only 9 recorded cases of viral shedding in milk samples, uncertain however of the viability of the particles. Furthermore, WHO and UNICEF strongly encourage commencing breastfeeding after parturition, underlining the benefits of lactation. Moreover, some studies have proven the existence of IgG and IgA anti-SARS-CoV-2-antibodies in the maternal milk that could possibly play an important part in the neonate’s protection against the virus. Vertical transmission through lactation seems unlikely, most studies pointing towards the safety of breastfeeding. However, further larger-scale studies need to be performed in order to clarify a yet uncertain matter.

Maternal milk microbiota and oligosaccharides contribute to the infant gut microbiota assembly

Breastfeeding protects against diseases, with potential mechanisms driving this being human milk oligosaccharides (HMOs) and the seeding of milk-associated bacteria in the infant gut. In a cohort of 34 mother–infant dyads we analyzed the microbiota and HMO profiles in breast milk samples and infant’s feces. The microbiota in foremilk and hindmilk samples of breast milk was compositionally similar, however hindmilk had higher bacterial load and absolute abundance of oral-associated bacteria, but a lower absolute abundance of skin-associated Staphylococcus spp. The microbial communities within both milk and infant’s feces changed significantly over the lactation period. On average 33% and 23% of the bacterial taxa detected in infant’s feces were shared with the corresponding mother’s milk at 5 and 9 months of age, respectively, with Streptococcus, Veillonella and Bifidobacterium spp. among the most frequently shared. The predominant HMOs in feces associated with the infant’s fecal microbiota, and the dominating infant species B. longum ssp. infantis and B. bifidum correlated inversely with HMOs. Our results show that breast milk microbiota changes over time and within a feeding session, likely due to transfer of infant oral bacteria during breastfeeding and suggest that milk-associated bacteria and HMOs direct the assembly of the infant gut microbiota.