Following a 2-year apprenticeship in a trout farm, Dr Holger Kühlwein studied agricultural sciences with a focus on animal nutrition at the Technical University of Munich (2002 – 2007) graduating with a BSc and a Diploma. Subsequently, Dr Kühlwein worked on product management for Trouw Nutrition Germany, before starting his Doctorate programme at Plymouth University (2009-2013) assessing health-related effects of yeast ß-glucans in cyprinids. Since 2013 he is Global Key Account Manager Aquaculture at Leiber GmbH, a German manufacturer of high-quality brewers’ yeast products. His main responsibilities include sales and technical support for key customers and distributors, and the strategic planning and organisation of R&D programmes.
- What inspired your interest in aquaculture and what led you to build your career in the sector?
It all started with my passion for fishing from kindergarten age, and – resulting from that – I developed a pronounced interest in fish and life under water in general. My initial plan for a professional career therefore was to follow a path towards river ecology, fish biology and related public consulting services. During my studies, I was increasingly surprised and impressed by the great significance of aquaculture on a global scale in serving the growing protein demand to humankind. In addition, I was intrigued by the diversity of aquaculture and its opportunities from a global perspective as compared to rather limited, local activities. So, I tried my best to actively push my studies and my early career towards international aquaculture.
- Your doctoral research focused on the effects of yeast ß-glucans in cyprinids. What were the most valuable lessons from that work and how relevant are brewers’ yeast products in today’s aquafeed industry?
Expect the unexpected and never give up! In hindsight and above all, successfully completing a PhD programme was character building. From a scientific point of view, we were looking at ß-glucans from a different perspective. They have been well-known for their beneficial effects on immune-competence and resilience already. However, at the time hardly anyone had looked at their potential effects on gut microbial communities and gut morphology at the micro- and ultra-structural level and we’ve gained some very useful new insights in that respect!
Today, brewers’ yeast derived products play an important role as functional feed ingredients, whereas the different fractions provide different functionalities. For example, autolysed yeast as an all-rounder provides both highly bioavailable nutrients and prebiotic cell wall components and is mainly used in larval and juvenile feeds. Highly purified ß-glucans in contrast are prophylactically used in a very targeted way to boost resilience prior to periods of expected higher stress and disease pressure.
- What are your observations, as the Key Account Manager Aquaculture at Leiber GmbH, on the key needs and day-to-day challenges fish farmers currently face?
In addition to market prices, disease pressure still seems to be one of the top concerns of farmers – as it has been for many years. Disease outbreaks not only reduce profits through increased direct costs (e.g. mortalities, reduced growth, treatment costs) but also through indirect costs (potential trade bans, reduced market prices, etc.). Concerted efforts in applying biosecurity measures, stress reduction and increased resilience of the animal are needed in order to reduce disease incidence and prevalence. Therefore, functional feed additives are just one piece of the puzzle!
Another important need on the small to medium-scale farm level is in the training and education of the farmers and their personnel with regards to the above mentioned points. Biosecurity and functional feeds, for example, are technically demanding and need detailed explanation and training.
- Looking ahead, which trends do you believe will have the greatest influence on the next decade of aquatic nutrition?
Given the continued growth of aquaculture and the limitedness of fish oils and proteins, the use of already existing and the search for new alternative resources will still be an important topic. In that context, also the integration of circular economy concepts – where reasonable and feasible – will gain further momentum, I believe. Another increasingly influential trend will be precision feeding, i.e. an ever more targeted feeding of fish and shrimp depending on their molecular needs under varying conditions (e.g. life stage, environmental conditions, immune burdens, RAS vs. more natural systems, etc.). And due to the continued disease pressure combined with the aim of a sustainable production with antibiotic reduction, the use of functional feed additives is set to further gain in importance – and not to forget the impact that climate change (water temperatures, ocean acidification, new emerging diseases, etc.) has in this respect.
- Given your close work with aquaculture customers and distributors worldwide, how do you assess the current state of the global aquafeed sector and which opportunities do you see for Leiber GmbH to build upon?
With the further increase of aquaculture and aquafeed production there will obviously be an increased demand in both raw materials and functional components. Our existing, multi-facetted portfolio and technical services are well prepared to provide reliable solutions. In addition, the recent pooling of competencies with Asahi Group Foods Ltd. in 2025 will greatly increase our options in terms of market reach, product portfolio and fundamental R&D.
A challenge however, that the global sector is facing, is to provide feeds which are both sustainably produced and economically feasible to the farmer – especially given the ongoing crises in Ukraine and the Middle East with energy costs and therefore production and logistics costs soaring. Our sustainability approach at Leiber GmbH with systems installed at our facilities to partially generate our energy needs ourselves on the ground (biomass heating plant, biogas plant) makes us a little less dependent on external sources and supports our supply chain reliability.
