Taurine and/or inorganic potassium as dietary osmolyte counter the stress and enhance the growth of GIFT reared in ion imbalanced low saline water

Rajendran Velselvi; Subrata Dasgupta; Tincy Varghese; Narottam Prasad Sahu; Gayatri Tripathi; Hougaina Panmei; Krishna Pada Singha; Gopal Krishna

doi:10.1016/j.fochms.2021.100058

Taurine and/or inorganic potassium as dietary osmolyte counter the stress and enhance the growth of GIFT reared in ion imbalanced low saline water

Food Chem (Oxf). 2021 Nov 29:4:100058. doi: 10.1016/j.fochms.2021.100058. eCollection 2022 Jul 30.

Authors

Rajendran Velselvi¹, Subrata Dasgupta², Tincy Varghese¹, Narottam Prasad Sahu¹, Gayatri Tripathi¹, Hougaina Panmei¹, Krishna Pada Singha¹, Gopal Krishna¹

Affiliations

¹ ICAR-Central Institute of Fisheries Education, Versova, Mumbai, India.
² ICAR-Central Institute of Fisheries Education, Salt Lake City, Kolkata, India.

Abstract

The effects of dietary osmolytes for alleviating osmotic stress and enhancing growth are not well elucidated in fish reared in inland saline water. The present study evaluated the effects of dietary taurine or potassium (K⁺) individually or in combination on growth, ionic homeostasis, and stress response of GIFT tilapia reared in potassium deficient low saline water (PDLSW, 10 ppt salinity) mimicking inland saline water. Isonitrogenous and isoenergetic diets supplemented with five potassium concentrations (0, 0.3, 0.45, 0.6 and 0.75 %), two taurine (T) concentrations (0.5 and 1.0 %) and two combinations of both (K⁺ 0.1 % + T 0.5 % and K⁺ 0.2 % + T 0.5 %) were fed to GIFT juveniles (4.4 ± 0.02 g body weight) and reared in PDLSW for 45 days. The fish fed on the diet fortifying with K⁺ 0.2 % + T 0.5 % showed the highest growth performance among the controls and other treatment groups. Dietary supplementation had no effects on PDLSW induced increase in osmoregulatory endpoints. The optimum dietary potassium requirement of GIFT reared in PDLSW was 0.57 and 0.599 g/100 g diet. Dietary K⁺ down-regulated the PDLSW induced expression of NKAa1, AQP1, and ClC2, whereas inhibited taurine-induced up-regulation of AQP1 and CLC2, which is the first report in tilapia. In addition, dietary K⁺ and taurine modulated antioxidant and metabolic enzyme activities for easing stress and balancing energy requirements. Thus, blending of potassium (0.2 %) and taurine (0.5 %) in the diet appears best to mitigate stress and enhance GIFT growth reared in inland saline water.

Keywords: AQP, Aquaporin; Aquaporin; CLC2, Chloride channel 2; Chloride channel2; GIFT; GIFT, Genetically improved farmed tilapia; NKA, Sodium potassium ATPase; Sodium potassium ATPase; Stress enzymes.