Browsing by Author "Sumagaysay, N. S."
ArticleNS Sumagaysay -
Aquaculture Research, 1999 - Wiley-BlackwellIntensified production of fish involves stocking at high densities and the use of artificial feeds. These practices result in eutrophication and environmental degradation mainly because of feed wastage and fish excreta. To minimize waste, the maximum amount of feed consumed by fish must be known. Food consumption and utilization, however, may vary with the size and physical condition of the fish. Milkfish Chanos chanos Forsskal and some hatchery-produced fish, such as seabass Dicentrarchus labrax L. have been observed to have morphological defects that could affect normal food intake and utilization. Jaw abnormalities in hatchery-bred milkfish interfere with feeding and result in very slow growth. In the Philippines, milkfish fry for production in ponds and cages are caught from the wild or produced through artificial spawning. Studies have been conducted to estimate the feed ration for milkfish reared in brackish water ponds where natural food contributes significantly to the nutrition of the fish. In ponds and marine cages, where fish are largely dependent on artificial feeds, daily feed ration has to be estimated. This study determined the maximum feed ration for different sizes of wild and hatchery-bred milkfish based on assimilation of energy.
Conference paperFP Pascual, NS Sumagaysay & IG Borlongan - In SS De Silva (Ed.), Fish Nutrition Research in Asia. Proceedings of the Fourth Asian Fish Nutrition Workshop, 3-8 September 1990, Vijayawada, Andhra Pradesh, India, 1991 - Asian Fisheries Society. AFS Spec. Publ. 5The study was conducted to determine the effectiveness of a practical diet, the profitability of feeding during 2 seasons, and the effect of a diet with coconut oil on the fatty acid profile of milkfish (Chanos chanos ) fingerlings. Milkfish fingerlings of average weight 6.2 g and 10.2 g were reared in earthen ponds of 3 compartments (550, 1,100 and 2,200 m super(2)) using the modular culture system. One month prior to harvest, fish in Treatment 1 were fed a practical diet containing 42% crude protein, 13.1% crude fat and 33.2% nitrogen-free extract while fish in Treatment 2 depended solely on the natural food in the pond. The fish fed during the last month of culture were heavier (141 g) than the unfed fish (100 g) in Experiment 1 (dry season) but had similar weights (44 and 41 g) in Experiment 2 (rainy season). Weight gain of fish in Experiment 1 was significantly higher than in Experiment 2. Varying temperature and salinity during different seasons influenced fish growth and production. Feeding milkfish was not profitable during the cooler months. Fatty acid profile in depot fat of fed fish reflected that of the diet. Palatability tests showed that fed fish were preferred to the unfed fish.