Impact of Vitamin K1 on Tissue Vitamin K Levels, Immunity, and Survival of Greenlip Abalone, Haliotis laevigata, at Summer Water Temperatures

Summer mortality impacts the productivity of greenlip abalone, Haliotis laevigata, on land-based farms in South Australia. It is associated with high water temperature (greater than 23°C), low dissolved oxygen levels, increased bacterial loads, and immune system suppression during summer months. This study aimed to alleviate mortality rates of greenlip abalone by dietary intervention using vitamin K1 to support the innate immune system and oxidative status. Dietary vitamin K1 at 0.0, 0.5, 1.0, and 5.0 mg kg^-1 was added to a commercially formulated diet mash. An additional diet containing 0.5 mg kg^-1 of K3 was also used for comparison. Diets were fed to 3-y-old abalone (71.51 g; 79.91 mm) at 22 and 25°C water temperatures for 39 days. No mortalities were observed at 22°C; however, high mortalities were observed in all dietary treatments at the water temperature of 25°C. Compared with the negative control diet (0.0 mg additional inclusion ofK1 or K3 kg^-1) at 25°C, the inclusion of vitaminK1 orK3 did not improve survival of greenlip abalone (P > 0.05). VitaminK1 inclusion level resulted in significant increases in vitamin K1 concentration of visceral organ and muscle tissues (P < 0.05). Steady-state levels of vitamin K1 were not reached. Steady-state levels of K2-MK-4 in visceral organ and muscle were reached when analyzed levels of dietary vitamin K1 reached 0.02 mg kg^-1. This was also true for K2-MK-7, but in the visceral organ only. Vitamin K1 inclusion level did not significantly affect total hemocyte count, phagocytic activity, or phagocytic index (P > 0.05). Increasing water temperature to 25°C resulted in significant increases in serum catalase activity (22 < 25°C) and vitaminK1 concentration in muscle tissue (22 < 25°C). Comparison of vitamin K1 or K3 at 0.5 mg kg^-1 resulted in significant changes to serum catalase activity (K1 > K3) and vitamin K1 concentration in visceral organ (K1 >K3). In conclusion, vitaminK1 at the doses tested, resulted in significant increases in vitaminK1 concentration in visceral organ and muscle tissues, but failed to improve immune function, oxidative status, or survival of greenlip abalone at high summer water temperatures.