The 12th International Milk Genomics and Human Health Symposium concluded Wednesday (28 Oct). This year the symposium returned to Sydney, Australia, where it was last held seven years ago. Comparing this year’s program and the program from 2008, I was struck by how the symposium has evolved, and certainly how the genomics of milk science has developed. Here are some of the main themes and findings:
1) As has become our tradition, the program opened with a stimulating overview of the exciting milk science and genomics research findings both past and present from Bruce German. Danielle Lemay followed with highlights from SPLASH! milk science update, and foreshadowed future topics. SPLASH! continues to expand its reach, with over 80,000 hits in the past year. The tone and pace of the symposium was set to go!
2) The symposium covered many topics, such as the nutritional and metabolic factors that affect mammary gland development and milk production. The influence of such factors on neonatal and lifetime health of the offspring was another subject of the meeting (Brand-Miller, Tellam, Rijnkels, Williamson, Elwood). The quality of nutrition and metabolic control in the mother during pregnancy clearly affects body composition in the newborn. There is a great deal of evidence that links these measures to health. Animal models are proving useful to explore the genomic mechanisms underlying these effects. Epigenetic marks, or chemical modifications that determine levels of gene expression, show complicated patterns of response to, for example, over nutrition during pregnancy. Different “programs” of genomic modification may account for subtle changes that, collectively, make an enormous difference to health or milk production.
3) A number of research presentations explored the theme of post genome-prediction phenotypes (Clark, Thomson, Abelsayed, Gregsen, Wang, Rochfort). Reflecting the consensus of his innovative dairy farmer team, Cameron Clark outlined the virtuous cycle of innovation and implementation of new advances. The rapid advances being developed in farm system management and instrumentation have delivered remarkable tools for measuring continuous and/or incredibly detailed phenotypes. The symposium presentations from these scientists provided striking examples showing the challenges of distilling the amount of data generated by these tools to interpret and apply the information they contain. As scientists, we recognize the inherent value of data collection, but we cannot possibly bury farmers with the weight and volume of data we can now so readily collect. One priority test for what to extract, says Clark and his farmer team, is the “so what” filter. Unless we can explain the value to farmers at the outset, it lacks purpose.
4) Symposium attendees were presented with elegant approaches to distilling large data sets from our statistician and geneticist colleagues (Thomson, Abelsayed, Reverter, Gregerson, Wang). They demonstrated how to turn complex biological data into parameters that constitute novel phenotypes, such as dam-offspring measures, extended lactation curves, health and welfare records, milk processing quality, and cow physiological data. Their approaches fit neatly into current herd improvement systems, showing how new and meaningful complex phenotypes could be integrated into state-of-the-art genomic selection criteria. However, they emphasized the necessity to use the most appropriate reference populations when incorporating phenotypic data for calculating genomic breeding values.
5) Milk oligosaccharides were once again an area of abiding interest (Frese, Sanctuary, Wang-B), but an analysis of milk lipids was also presented in this context (MacGibbon). Consumption of milk and milk-derived constituents affects the nexus between gut, immunity, brain, and health. Oligosaccharides in milk have apparently evolved to pair with healthy commensal microbes to prime healthy gut development. The complex subject of cognition in children and the challenges presented by pre-term birth are also areas of increasing research effort.
6) Gut microbiota is fundamental to a healthy start in life, but the use of milk constituents to modulate gut health can potentially impact a range of other outcomes. Symposium attendees heard evidence of milk oligosaccharides and milk exosomes reducing inflammation in animal models of arthritis (Stahl, van der Loo). Milk constituents have a modulating effect at the cellular level and promote balance in the immune system. Another related area is the intriguing question of whether milk miRNA, which is a feature of milk across diverse species of mammals and even monotremes (platypus and echidna), has a specific role (Gillespie, LeFevre). Probiotics based on the milk-selected commensal bacteria and their possible interactions with miRNA are also emerging in health promoting products (Simpson-M, Demers-Mathieu). A comparative analysis of protein digestion into bioactive peptides, using peptide analysis of human and bovine milk, documented the potential range of antimicrobials and other potential bioactives. The use of highly sensitive mass spectrometry instruments captured and identified these peptides in microliter volumes of pre-mature baby stomachs, helping to understand their importance (Dallas).
7) The meeting concluded with an elegant exposé on the emerging paradigm of nutritional impact based on macronutrient balance (Simpson-S, Raubenheimer). A wealth of data from laboratory and field studies, and across species as diverse as flies and orangutans, was presented to support the Protein Leverage Hypothesis. Protein emerges as the primary driver of dietary choice and calorie intake. The evidence points to a wide-ranging impact of dietary protein on appetite, metabolism, longevity, and reproductive fitness, amongst others. The implications for the consumption of milks of different species, and for formulations based primarily on cow’s milk were a lively and fascinating point of discussion.
Once again, an enjoyable social program complemented the scientific program. The highlight was the traditional harbor cruise—always a wonderful way to view the iconic sites of Sydney. The symposium was diverse, informative, and invigorating. Personally, I find that it challenges the mind and sustains the enthusiasm for more of the wonderful multi-disciplinary world of milk genomics and human health research. In conclusion, I would like to thank the IMGC sustaining members and sponsors, all those who contributed, and a special thanks to Laurie Jacobson and Gonca Pasin for terrific and generous support.
Professor Peter Williamson
Associate Professor, Physiology and Genomics
University of Sydney, Australia