Projects

We recognize the following main areas in our work: 1) modification of fish, 2) feeds, and 3) feeding methods that help fish thrive in more sustainable environments. All these areas stand on four research pillars that our lab represents: nutritional and environmental programming, gut healing, and larval nutrition.

Modification of Fish

Nutritional Programming

Replacement of fishmeal (FM) in aquaculture diets with plant protein (PP) has been an ongoing challenge. High-quality PP concentrates are widely used since their digestibility can be comparable to FM. However, their price can exceed the cost of marine raw materials. Progress with utilization of lower-quality PP meals has been made but a number of concerns must be overcome to maintain acceptable growth rates and feed efficiency values at high FM substitution levels. For example, the presence of anti-nutritional factors in PP have been associated with intestinal inflammation in fish, which can decrease the capacity of fish digestive tract to digest, absorb, and utilize nutrients.

One of our main focuses in improving PP utilizaiton has been placed on nutritional programming (NP) - a promising approach that offsets the negative effects of dietary PP in adult fish through brief introduction of PP at an early age. Our lab developed an unconventional NP strategy using live food as PP vehicle. By using enriched live food to program fish at first feeding, we can begin introduction of PP to the fish at the earliest possible point. The combination of live food and PP provides all the nutrients required for proper growth and development while also exposing the fish to alternative raw materials and their associated anti-nutritional factors delivered at low enough concentrations.

Why is this important? This feeding strategy becomes a feasible and practical way of enhancing fish utilization ability of diets based on almost any raw material.

Environmental Programming

Aquaculture continues to significantly increase its production, making it the fastest-growing food production sector worldwide. However, the sustainability of the sector is at risk due to the predicted effects of climate change. Climate change can negatively influence food security through increased water scarcity and increased global temperatures.

The metabolic rate of poikilothermic (cold-blooded) animals, such as fish, is controlled by temperature and, hence, every species has an optimal temperature range. Any changes in that optimal range, whether it is water that is warmer or colder, can lead to reduced growth performance and/or survival. However, animals, are also characterized by a certain degree of environmental plasticity and many of their traits related to behavior, stress response, social skills, can be influenced by early life experiences.

Similar to nutritional programming, we aim to understand how brief exposure to stress (such as high temperature) induced during early development in a hatchery affects the growth, survival, feeding efficiency, and stress response in adult fish. We believe that short exposure to different stressors during early development can induce changes in the fish leading to better adaptation to similar conditions experienced later in life.

Why is this important? We strongly believe that this environmental programming approach can become an effective tool in generating fast growing and more resilient future fish generations that will be able to withstand water changes associated with global warming.

Modification of Feed and Feeding Methods

Larval Nutrition

To intensify fish production, aquaculture has been moving towards sustainable farming intensification, which utilizes indoor recirculation systems. Such technology, however, poses a challenge related to the lack of naturally occurring live food that larval fish prey on. Therefore, the substitution of live food with formulated diets for the early stages of fish has been a major focus in aquaculture during the last decades to reduce costs and increase juvenile production. Different types of formulated feeds have been examined, including dry or frozen live food organisms, feeds supplemented with digestive enzymes, and formulated food particles made using different processing methods. However, weaning most first feeding larval fish completely onto formulated dry feeds has not been fully possible yet.

The larval digestive tract is often not completely developed during the first weeks of life, and therefore protein digestion significantly limits the utilization of formulated feeds in larval fish. Our lab proposed for the first time utilization of adult fish digestive tract to digest protein source for larval fish of the same species. Specifically, digestive tracts obtained from adult fish were used to hydrolyze the muscles of low-value invasive species (i.e. Bighead carp) to generate optimal protein hydrolysate that could be easily assimilated within the primitive digestive tract of larval fish. This novel dietary ingredient approach supported growth and development of fish larvae in different species which likely resulted from matching the specific requirements of the larvae with respect to their digestive organ development, levels of digestive enzymes present in the gut, and nutritional requirements.

Why is this important? This outcome has created three main opportunities: 1) utilization of invasive species and fish byproducts in the production of high-quality protein ingredients for larval feeds, 2) production of more robust and healthy larval fish with better adaptation capacity to formulated diets, and 3) successful approach in the development of high-quality starter feeds that supports sustainable expansion of the hatchery sector.

Gut Healing

Soybean meal (SBM), as well as many other lower-quality PP sources, contain large amounts of non-starch polysaccharides and anti-nutritional factors that negatively affect the growth and intestinal health of both omnivorous and carnivorous species. Therefore, a large portion of our research has focused on the development of mitigation strategies towards reducing gut inflammation in fish. First, we have identified alternative feeding strategies. We found, for example, that alternating feeding using FM and SBM-based diets can help fish achieve growth performance similar to those fed FM diet continuously and reduce the overall cost associated with feeding. Second, we have developed “functional feed” approaches that can help counteract inflammatory triggers induced by SBM. Specifically, we have identified certain compounds such as dipeptides (carnosine and anserine) or essential oil extracts (i.e. oregano) as health-promoting additives which can improve growth performance and intestinal lining of fish fed high SBM-based diets. Finally, we have also investigated non-invasive methods in detection of gut inflammation in fish through analysis of biomarkers such as calprotectin and lipocalin in fecal samples. These non-fatal health indicators have potential to help farmers detect the onset of gut inflammation in their fish before it significantly impairs their overall performance.

The innovative approaches to gut healing we have developed are not focused on modifying the quality of SBM but rather on changing current feeding protocols or adjusting/improving the commercial feed formulations with the addition of health supplements to accommodate higher levels of the existing conventional SBM.

Why is this important? The outcomes of this work provide feed producers with the possibility of using higher levels of SBM in feeds allowing for more flexibility in formulations of diets deprived of FM and high-cost protein concentrates/isolates.