Vol. 10, Special Issue 7 (2021)

Author(s):
Asim Iqbal Bazaz, Tasaduq H Shah, Farooz A Bhat, Adnan Abubakr, Bilal A Bhat, Rizwana Malik, Nafhat-Ul-Arab and Irfan Ahmad

Abstract:
The aim of this study was to compare the effects on early survival rates of rainbow trout eggs exposed to heat shock shortly after fertilization. Four different treatments and a control group were used; each treatment group was replicated thrice. Heat shock at 26 ^oC and 28 ^oC for 10 min. duration were applied 15 min. and 20 min. after fertilization using a water bath. No treatment (heat shock) was given to Control. The highest fertilization rate among the treatment groups was observed in group T1 (26 ^oC, 15 min. after fertilization) at 90.393±0.37%, while the lowest fertilization rate of 88.483 ± 1.68% was observed in group T4, heat shocked at 28 ^oC, 20 min. after fertilization. However, the fertilization rate for the control group observed was 93.16±0.41%. It was found that the fertilization rate was higher in control group as compared to treatment groups. There was a significant difference (P<0.05) between the treatment groups and control group. The highest hatching rate among the treatment groups was observed in group T2 heat shocked at 26 ^oC after 20 min. of fertilization (81.843±0.88%), while the lowest hatching rate o(72.153± 1.17%) was observed in group T3 heat shocked at 28 ^oC after 15 min. of fertilization. The hatching rate was higher (84.28±0.46%) in control group as compared to treatment groups. It was observed that increasing heat shock intensity reduced the survival percentage of eggs from fertilization to hatching, however by increasing time after fertilization hatching rates also increased. Fertilization and hatching rates showed significant differences (P<0.05) between treatment groups and control group.