ISSUE FOCUS 28 FEED & ADDITIVE MAGAZINE January 2023 The combination of growth and increased survival during pathogenic pressure showed that including selenium in the diet can be a viable strategy to reduce antibiotic use in aquaculture. PHYTOGENIC FEED ADDITIVES: GARLIC AND CINNAMON Phytogenic feed additives are based on plant-derived materials. Phytogenic feed additives are widely known as appetite stimulators, growth promoters and immune stimulants. Additionally, they have anti-pathogenic, anti-bacterial and anti-parasitic properties. For example, garlic and cinnamon contain several bioactive molecules that can exert multiple effects on gastrointestinal (GI) health. This includes antimicrobial effect by disrupting the cellular membrane of pathogens. Additionally, it can cause a boost of the host immunity providing support in anti-inflammatory and antioxidant reactions, and resulting in the redirection of energy to maintain or even increase animal performance during pathogenic challenges. In aquaculture, the use of garlic and cinnamon to support fish in their defense against pathogens is widely accepted. For example in cobia fish, it is observed that the inclusion of 1 kg/MT of a garlic and cinnamon product, in the form of Excential Alliin Plus (Orffa Additives BV), has led to a significant decrease in the occurrence of sea lice on the fish by 60% (Table 1). Additionally, it was observed that the size of the wounds, caused by sea lice on the fish fed the garlic and cinnamon product, were smaller and, in those fish, wound regeneration capacity was also increased. In shrimp, similar results have been observed. In a trial performed in Thailand, by Dr Orapint, shrimp were fed either 0, 0.5 or 1 kg/MT from the garlic-cinnamon blend (Excential Alliin Plus, Orffa Additives BV). Addition of the phytogenic feed additive led to increased growth performance and feed efficiency, regardless of the source. But next to that, the inclusion of the garlic-cinnamon blend in the diet led to overall higher disease resistance. The same shrimp were challenged with Vibrio parahaemolyticus, after which immune parameters were measured. In general, hemocyte count, hemolymph protein and phenoloxidase activity were all elevated by the garlic-cinnamon blend (Figure 2). These parameters are indicators of the innate immune response and antioxidant capacity, which aid the shrimp in a swift and effective response against pathogens. Besides these parameters, lysozyme activity was significantly improved when the garlic-cinnamon blend was added at 1 kg/MT. Both trials showed an increased resilience against common disease in aquaculture when adding a garlic-cinnamon blend to the feed, decreasing the need for antibiotics. Table 1. Sea lice count in cobia fish fed diets with (1 kg/MT; cages 1, 2, 4, 5, 7, 8 and 9) and without Excential Alliin Plus (cages 3 and 6) wk 4 wk 5 wk 7 wk 8 wk 9 ave Cage 1 0,5 1,2 5 10,4 4 4,2 Cage 2 0,7 0,4 2 1 0,2 0,9 Cage 4 0 4,6 5 3,8 0,2 2,7 Cage 5 0,4 2 0 4,4 1,2 1,6 Cage 6 0 0 2,4 2,2 0,8 1,1 Cage 7 0 2 6 14,7 6,8 5,9 Cage 8 2,1 1,1 1,8 3,2 0 1,6 Average Alliin Plus 0,15 0,55 1,20 2,10 1,10 1,05 Cage 9 0,7 3,5 - 3,6 1,2 2,3 Average Control 0,63 2,11 3,30 5,87 1,94 2,74 Cage 3 0,3 1,1 0 2 1,4 1
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