Effects of Bovine Growth Hormone on Growth of Carp (Cyprinus carpio) and the Influences of Temperature and Photoperiod

Abstract

Experiments were conducted on young-of-the-year or yearling carp (Cyprinus carpio) to determine the influence of temperature and photoperiod on the growth promoting ability of bovine growth hormone, and the dose–response relationship of bovine growth hormone on carp growth. There was relatively greater enhancement of growth due to bovine growth hormone at an above optimum temperature for growth, 35 °C, than at the optimum temperature, 30 °C. This was possibly due to decreased production or activity of endogenous growth hormone at the higher temperature, resulting in a greater relative response to the exogenous bovine hormone. Inhibition of endogenous growth hormone may be a major limiting factor to growth at above optimum temperatures. Daylengths of 9 and 16 h had no effect on the response of the fish to hormone injections. At a temperature of 35 °C fish receiving bovine hormone dosages of 12.5, 25, 50, and 100 μg/g per wk responded with increasingly greater growth rates over fish receiving sham injections. Condition factors of fish increased throughout most of the experiment with greater increases among hormone injected fish.