Aquafeed Vol 13 Issue 4 2021

Page 50


The gut health revolution Marta Arredondo Luque, Novation 2002

Ensuring efficient and sustainable aquatic production is not always an easy task. Aquaculture encompasses a high diversity of species with very diverse feeding habits and cycles which hinders the use of a unique solution. Aquaculture production has been growing exponentially for years and the World Bank estimates that by 2030, 62% of fish produced worldwide will come from aquaculture. To meet the future demand, aquaculture must find a solution to challenges, such as fishmeal (FM) and fish oil (FO) substitution, reduction of chemical use and antibiotic resistance and improve immune response against pathogenic challenges.

Fishmeal and fish oil substitution Aquatic production is extremely dependant on FM and FO supply, pressuring wild stocks and making unsustainable aquaculture grow. Numerous plant have been tested as protein and oil sources for feeds. However, these protein sources have antinutritional factors and can have detrimental effects on growth performance and welfare as well as increasing feed and nutritional waste. Soybean meal (SBM) is a high protein source and is currently a commonly used protein source in aquafeed including carnivorous species. However, high inclusions of SBM have detrimental effects on gut health causing enteritis, high vulnerability against pathogenic challenges (bacteria, parasites, or toxins), and changes in the absorptive cells provoking inflammation and villi shortening. Improve resistance against pathogenic challenges Over-replacement of FM can also lead to inferior performance and poor disease resistance, negatively affecting the oxidant-stressed status and induced SBM inflammatory response. Several studies have demonstrated that high inclusions of SBM disturb oxidative homeostasis in fish. The imbalance between

reactive oxygen species (ROS) generation and elimination can cause oxidative stress. Sensitivity to novel protein raw materials in feed has also been observed in several aquatic species, resulting in strong immune responses. Induced SBM enteritis in Atlantic salmon, carp and turbot has been long known. Cytokines play a key role in the regulation of the immune response. Intestinal inflammatory response with the combination of proteins and antimicrobial peptides are crucial for the control of pathogens. Previous studies confirm that inflammation response might be deteriorated via down-regulation of anti-inflammatory cytokines (IL-1β and TNFα) and up-regulating of pro-inflammatory cytokines (TGF-β and IL-10).

Reduction of chemical use and antibiotic resistance The intensification of aquaculture in the past forced the industry to look for solutions to increase survival even when welfare was not ideal. The constant bacterial and parasitic outbreaks were difficult to control, and the use of antibiotics and chemical products was the only solution at the time. In the past, and currently in some countries, there is excessive use of antibiotics to prevent and/or control infectious diseases caused by bacterial pathogens and for growth-promoting purposes. Public awareness of the potential harm to public health due to antibiotic residue bioaccumulation and antibiotic resistance led to their ban on animal feed formulation. All these challenges led to the search for feed additives for a more sustainable aquaculture. The benefits of using butyric acid in aquaculture Aquafeeds use additives to supplement the nutrients to counteract the lack of some essential nutrients. However, additives look into a more functional approach. These so-called “functional nutrients” affect

Aquafeed: Advances in Processing & Formulation Vol 13 Issue 4 2021

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