Induced maturation and spawning of milkfish, Chanos chanos Forsskal, by hormone implantation
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The milkfish, Chanos chanos Forsskal, does not reach gonadal maturity easily in captivity. In an attempt to induce maturation, exogenous hormones, LHRH-A and 17α-methyl-testosterone, were implanted into adult milkfish either alone or in combination. The hormones were delivered using cholesterol pellets (LHRH-A) or silastic tubing sealed with elastomer (17α-methyl-testosterone). The fish were implanted three times at monthly intervals between March and May of 1985. The combination of LHRH-A and 17α-methyl-testosterone induced significantly more maturing fish (P < 0.05) than LHRH-A alone or sham controls; 88%, 38%, and 13%, respectively. Fish with average egg diameters between 768 μm and 905 μm, spawned 48 h after hormone implantation. These results indicate that the maturation and spawning of milkfish in tanks can be induced and accelerated 1–2 months earlier than the beginning of the normal spawning season through hormone implantation.
This research work was supported by a grant from USAID (DAN-4161-A-00-4055-00).
CitationLee, C., Tamaru, C. S., Banno, J. E., Kelly, C. D., Bocek, A., & Wyban, J. A. (1986). Induced maturation and spawning of milkfish, Chanos chanos Forsskal, by hormone implantation.
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Conference paperLV Benitez - In RD Fortes, LC Darvin & DL de Guzman (Eds.), Fish and crustacean feeds and nutrition : Proceedings of the seminar-workshop on fish and crustacean feeds and nutrition held on 25-26 February 1985 at UPV, Iloilo City, 1989 - Philippine Council for Aquatic and Marine Research and DevelopmentThis paper reviews recent work on milkfish nutrition. Substantial progress had been made towards understanding the digestive physiology of milkfish. Major enzaymes envolved in the digestions of carbohydrates, protein and lipids had been detected in the pyloric caece, intestines and pancreas of milkfish. The most active carbohydrates were involved in the hydrolysis of α - glocosidic bonds. Intestinal amylase activity consistently reached the peak at about noon when milkfish gut was full. This confirms that milkfish is s daytime feeder. No cellulase activity was detected in any region orf the digertive treat although the fish relies heavily algae and other plant source for food. Trypsin, chymotrypsin and general proteases were also detected in milkfish digestive tract. A powerful milkfish trypsin inhabitor was detected in the filementous algae, Chaetomorpha brachygona which is predominant species in lumot. Lipass in the pancreas and intestines had two pH optima, suggesting a physiologic versatility for lipid digestion in milkfish. There is a limit information on the nutrient requirement of milkfish. Most studies showed that milkfish fry has a dietary requirement of 40% protein, and 7-10 lipid. Studies on the protein-energy requirement of fingerlings suggested that 30-40% protein, 10% fat and 25% carbohydrates are required. Subsequent studies showed an optimum protein energy to total metabolizable energy ratio of 44.4%. Amino acid test diets for milkfish had been formulated to contain white fish meal, gelatin and approprate amino acid mix.
Lactate dehydrogenase isozyme patterns during the development of milkfish, (Chanos chanos (Forskal)) PD Requintina, LM Engle & LV Benitez -
Kalikasan, The Philippine Journal of Biology, 1981 - University of the Philippines at Los BañosPolyacrylamide disc gel electrophoresis was done to determine the lactate dehydrogenase (LDH) isozyme patterns for fry (5-3 mg), fingerling (6-12 g), pond-size (150-250 g) and adult (6-9 kg) milkfish. The patterns were tissue specific; the different tissues examined, viz., eye, liver, heart, and skeletal muscle had different expressions of LDH isozymes. The resolved patterns appeared to be products of LDH gene loci A, B, and C. Subunits A and B were present in all tissues. A4 and B4 were predominant in skeletal and heart muscle, respectively; the two associated non-randomly in vivo and formed only the heteropolymers A3B and AB3. A liver band, L4, was most conspicuous in the fingerling, pond-size, and adult; it was assumed to be coded by locus C. A negatively charged band, X4, was detected in fully developed ovary and in fry homogenized as whole individuals, but it could not be resolved in tissues of fingerling. Six-mo old stunts and 3-mo old fingerlings had similar LDH patterns for all tissues examined. The patterns for 11-mo old stunts and fingerlings also were similar but the one for the eye of the former was the same pattern resolved for the eye of adults. There was no change in the LDH isozyme patterns of milk fish stunted for 6 mo under different salinity levels (0-5, 15-20, 32-35 ppt).
Production of hatchery-bred early juvenile milkfish (Chanos chanos) in nursery ponds through supplemental feeding CJ Jaspe, MSM Golez, RM Coloso & CMA Caipang -
Animal Biology and Animal Husbandry, 2012 - Bioflux SocietyHatchery-bred early juvenile Milkfish (Chanos chanos Forsskål, 1755) (average weight of 0.45 g) were stocked in a 500 m2 nursery pond at a density of 16 juveniles/m2 during the dry months (March-May). The early juveniles were reared for two months with natural food followed by supplemental feeding. Upon the harvest the fish reached an average weight of 9.30 g and a survival rate of 86.9%. A feed conversion ratio (FCR) of 1.08 was attained, with specific growth rate (SGR) of 4.96%/day. The high survival rate and good production could be attributed to the time of the year when the nursery production trial was conducted. The nursery of milkfish in ponds during the summer months ensures sufficient supply of natural food and stable water quality during the crucial phase in the nursery production. This strategy of rearing early juveniles (<1 g) of milkfish in nursery ponds at high stocking densities using a combination of natural food and supplemental feeding could be one of the alternative approaches in the nursery production of this fish.