Application of fish gelatin as diet binder in diets for the common carp Cyprinus carpio L. fingerlings

Abstract

Fish gelatin applied as an animal source binder and stabilizer in diets for the common carp Cyprinus carpio L. fingerlings in comparison with binder void diet. Experimental diets prepared from standard raw materials adding laboratory made fish gelatin at 1% as binder. Three types of gelatin applied (extracted from tilapia Tilapia zilli skins, common carp Cyprinus carpio L. gas bladder and barred needlefish Ablennes hians heads). Three diets containing each type of extracted gelatin were prepared to compare with gelatin void diet. Fish initial average weight 5.56 gm were fed at 5% body weight daily. Chemical and physical analyses performed on pellets thrown into water to feed fish as affected by added gelatin. The influences of gelatin monitored on pellet density, floating period, sinking velocity, water absorption rate and disintegrating rate as indicators for pellet quality and resistance into water. Feed intake by fish during research period studied also. Results showed that bladder gelatin diet gave the highest weight increase in comparison with other diets which reached 15.6gm. Physical measurements demonstrated that the highest density recorded in bladder gelatin diet (1.4 gm/cm 3 ) followed by head and skin gelatin diets (1.3 gm/cm 3 ) while the lowest density recorded in gelatin void diet (1.1 gm/cm 3 ). Floating time of 8.55 sec. and sinking velocity of 1.06 sec./cm recorded for bladder gelatin diet in comparison with 7.53, 7.31 and 5.30 sec. for floating time and 1.37, 1.43 and 2.47 sec./cm for sinking velocity of diets containing head , skin gelatin and control, respectively. Various treatment indicated impacts on growth where weight increase rated 10.26-15.6 g, specific growth rate 1.10-1.61 and relative growth rate 39.46-62.40 %. Bladder gelatin diet surpassed others in weight increase, specific and relative growth rates. Feed conversion ratios reached 3.156, 2.862, 3.597 and 4.306 for skin, bladder, head gelatin and control diets, respectively. As for feed intake, bladder gelatin treatment gave the highest values. Chemical composition did not affected by using binders.