The effect of thyroxine (T4) on prematurating in female, on survival percent, growth and development of egg and larval in rainbow trout, grass carp, silver carp and barbell of Caspian Sea

Abstract

Studies show that thyroxine can play an important role in regulating growth and other physiology activities. Since the direct role of thyroxine in growth metamorphose larval of bony fishes hasn't been proved yet, during the experiment accomplished in Shahid Ansari and Jajrood station, the hormones function in the survival of development of silver carp, grass carp and rainbow trout were studied. In this study accomplished of thyroxine baths with 0.1, 0.5 and 1 ppm (with 3 repeat). The other phase, thyroxine injected to females grass carp, silver carp, rainbow trout and barbell of Caspian Sea with different doses (1, 10 and 100 g/g B.W.). Tehn survival of development of embryo and larval and precent of fertilization were studied. Also, the percent of mortality were compared in two phases in stages of development. Result show that: 1) Trout: a)Phase of thyroxine bath: The number of hatching eggs and survival of larval in 0.5 ppm were increased to other treatment. b) Phase of hormone injection : The survival of larval in treatment of 10 g/g was 8.58% that was meaningful difference to other treatment (P<0.05). 2) Silver carp: a)Phase of thyroxine bath: The number of hatching eggs and survival of larval in 0.5 ppm were ( 20%) increased to other treatment (P<0.5). b) Phase of hormone injection : The survival of larval in treatment of 10 g/g was meaningful difference to other treatment (P<0.05). 3) Grass carp : a)Phase of thyroxine bath: The number of hatching eggs and survival of larval in 0.5 ppm were 39% increased to other treatment. b) Phase of hormone injection : The survival of larval in treatment of 1 g/g was meaningful difference to other treatment (P<0.05). 4) Barbel of Caspian Sea: Development stages wasn't determined in this fish. Number of eggs degenerated , number of eggs were the first development stages and growth of numbers increased on ovary.