Effects of dietary tryptophan levels and fish stocking density on immunological and antioxidant responses and bactericidal activity againstAeromonas hydrophilain rainbow trout (Oncorhynchus mykiss)

Abstract

Rainbow trout (Oncorhynchus mykiss) was reared under low (LD) and high (HD) stocking densities for 70 days, during which they were fed with diets supplemented with 0, 5 and 10 g tryptophan (Trp) per kg. At the end of the experiment, there were significant interaction effects of the stocking density and Trp levels on plasma Trp, globulin, lysozyme, catalase (CAT), malondialdehyde (MDA), and bactericidal activity and blood leucocyte count. However, there was no difference in plasma complement (ACH50), total immunoglobulin (Ig), total antioxidant capacity (TAC), superoxide dismutase (SOD) and blood differential leucocyte count. Trp at 5 g per kg diet significantly increased lysozyme and bactericidal activity, and decreased MDA under both the LD and HD conditions. Moreover, it significantly increased plasma CAT and blood leucocyte under the LD and HD conditions respectively. Trp at 10 g per kg diet significantly increased blood leucocyte and plasma bactericidal activity under the LD condition, but significantly decreased plasma globulin and bactericidal activity under the HD condition. In conclusion, the present results showed that the effects of Trp on immune and antioxidant systems depend on Trp levels and stressful conditions. As 5 g Trp per kg diet is beneficial for rainbow trout well‐being under both the LD and HD conditions, higher level of Trp (10 g/kg) is not beneficial and even causes some negative effects under the HD condition.

Subcellular component of Bacillus subtilis (AN11) induces protective immunity against Aeromonas hydrophila in Labeo rohita (Ham.)

“…This enzyme breaks down the linkages of β‐1‐4 glycosidic bond present in the cell wall of bacteria that is between N‐acetylmuramic acid and N‐acetylglucosamine, thus inducing bacteriolysis to control the infection (Mukherjee et al, 2019). The increase in lysozyme in serum during the administration of immunostimulants indicates the increase in numerous humoral factors which protect the fish during pathogenic invasion (Hoseini et al, 2020; Hoseinifar et al, 2019). Our findings showed that the fish serum lysozyme activities were substantially increased in the subcellular injected group when compared with the control group.…”

The positive effects of taurine on growth performance, immunohaematological parameters and stress response of farmed beluga ( Huso huso ) in both fresh water and brackish water

“…Stress physiology, markers of HSdensity stress and the effects of water quality, feed and water additive to reduce stress were reviewed by Baldwin (2011). Positive effects of feeding fish with some additives such as vitamins (Bacchetta et al, 2020;Naderi et al, 2017), fatty acids (Bahurmiz & Ng, 2007), amino acids such as arginine (Hoseini et al, 2019), tryptophan (Hoseini et al, 2020) and minerals (Adineh et al, 2020;Naderi et al, 2017) to reduce HSdensity stress have been found.…”

Study on growth enhancement and the protective effects of dietary prebiotic inulin on immunity responses of rainbow trout (Oncorhynchus mykiss) fry infected with Aeromonas hydrophila

“…As the innate immune system in fish is vital in the response to primary stressors, as well as infectious diseases, the enhancement of innate immune responses, disease resistance, and subsequent improvement in health are of growing interest to researchers (Song et al, 2014;Yan et al, 2017;FAO, 2018). Immunostimulants present a promising approach to prevent and/or control diseases in aquaculture (Chakraborty and Hancz, 2011;Hoseinifar et al, 2015;FAO, 2018;Hoseini et al, 2019). Prebiotics have recently attracted extensive attention in aquaculture (Ringø et al, 2010), as non-digestible food ingredients that metabolizable through gut microbiota (Ringø et al, 2013).…”