Effects of Partial and Full Feed Restriction on the Plasma Levels of Thyroid Hormones and Testicular Activity in the Male Air-breathing Catfish, Clarias gariepinus during Different Phases of the Breeding Cycle

Proforma Suchiang,B B P Gupta

doi:10.5539/ijb.v3n2p32

Abstract

The effects of partial and full feed restriction on the plasma levels of thyroxine (T4), triiodothyronine (T3) andtesticular activity were studied in the male air-breathing catfish, Clarias gariepinus. Partial and full feedrestriction for 3 weeks significantly decreased the plasma T4 levels during the progressive and breeding phases,and decreased the plasma T3 levels only during the breeding phase. However, full feed restriction for 3 weeksincreased plasma T3 levels and T3/T4 ratio during the quiescent, progressive and regressive phases. Histologically,3 weeks of partial and full feed restriction markedly reduced the testicular activity during the progressive andbreeding phases. These results indicate that partial and full feed restriction adversely affects the thyroidhormonogenesis and testicular activity in a phase-dependent manner in C. gariepinus.

Highlights

The effects of partial and full feed restriction on the plasma levels of thyroxine (T4), triiodothyronine (T3) and testicular activity were studied in the male air-breathing catfish, Clarias gariepinus
Under natural conditions the fish physiology changes with the phase of the breeding cycle, there is a possibility that the effects of feed restriction on the levels of thyroid hormones and gonadal activity may vary with the phases of the annual breeding cycle of the fish
Partial feed restriction for 3 weeks significantly decreased the plasma T4 levels during the progressive and breeding phases as compared to the ad libitum fed control group, while it had no effect on T4 levels during the quiescent and regressive phases (Figure 1)

Summary

Introduction

The effects of partial and full feed restriction on the plasma levels of thyroxine (T4), triiodothyronine (T3) and testicular activity were studied in the male air-breathing catfish, Clarias gariepinus. 3 weeks of partial and full feed restriction markedly reduced the testicular activity during the progressive and breeding phases. Starvation has been reported to affect reproductive function in different fish species (Silverstein and Shimma, 1994; Karlsen et al, 1995; Collins and Anderson, 1999; Duston and Saunders, 1999; Frantzen et al, 2004) These reports on the effects of feed restriction on the thyroid hormones and gonadal activity are limited to only a few temperate zone fish species and without any reference to the phases of the annual breeding cycle when the studies were conducted. In this study in a tropical/subtropical region we have determined whether feed restriction affects the plasma levels of thyroid hormones and testicular activity in a phase-dependent manner in the male African catfish, Clarias gariepinus

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Conclusion