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    • Article

      Effect of prepared diet and vitamins A, E and C supplementation on the reproductive performance of cage-reared bighead carp Aristichthys nobilis (Richardson) 

      CB Santiago & AC Gonzal - Journal of Applied Ichthyology, 2000 - Blackwell Publishing
      Twenty-month-old bighead carp, Aristichthys nobilis (Richardson), were fed prepared dry diets for 20 months in cages in Laguna de Bay, Philippines, to determine the effect on reproductive performance. The experimental diets were similar in composition except for the combinations of vitamins being tested. Diet 1 was supplemented with vitamins A, E and C; diets 2, 3 and 4 each lacked one of the supplementary vitamins; and diet 5 did not include any vitamin supplementation. Bighead carp that relied solely on natural food without a prepared diet served as a control. The total of six treatments each had two replicates. Results showed that the onset of gonad maturation was 2–3 months earlier in the fish that were fed the prepared diets regardless of vitamin supplementation, when compared with the fish that were fed natural food (control). Moreover, the prepared diets enhanced egg hatchability which was significantly higher in fish that were fed diet 1 (+ vitamins A, E and C, 80.5 ± 18.1%) and diet 3 (– vitamin E, 78.5 ± 1.1%) than in those fish that were fed natural food (control) (36.5 ± 31.3%). Mean number of 3-day-old larvae was highest in fish fed on diet 1 (34 525 ± 1732), followed closely by fish that were fed diet 3 (32 420 ± 3909). A low number of 3-day-old larvae was obtained from fish fed the natural diet (14 490 ± 4331) as well as in fish that were fed diet 2 (– vitamin A, 14 347 ± 4863), diet 4 (– vitamin C, 21 407 ± 5840) and diet 5 (– vitamin A, E and C, 12 191 ± 1439). Other criteria for reproduction such as relative fecundity, fertilization rate, and hatching rate did not differ significantly (P > 0.05) among treatments. The addition of vitamins also had no significant effects on weight gain of adult fish.
    • Conference paper

      Response of Nile tilapia (Oreochromis niloticus) fry to diets containing Azolla meal 

      CB Santiago, MB Aldaba, OS Reyes & MA Laron - In RSV Pullin, T Bhukaswan, K Tonguthai & JL Maclean (Eds.), The Second International Symposium on Tilapia in Aquaculture, 16-20 March 1987, Bangkok, Thailand, 1988 - Department of Fisheries, Bangkok, Thailand; International Center for Living Aquatic Resources Management
      Sun-dried Azolla pinnata was ground and incorporated into experimental diets at various levels (8.50, 17.00, 25.46, 34.00 and 42.45% of the diets) to replace fish meal in a control diet isonitrogenously. All feeds contained 35% crude protein and 250 kcal digestible energy/100 g. They were fed to Nile tilapia (Oreochromis niloticus ) fry (mean body weights, 14.9 mg in Experiment I and 11.2 mg in Experiment II) at 45% of fish biomass daily for 7 weeks. Results of the 2 experiments showed that Azolla meal is a suitable component of diets for Nile tilapia fry. Growth increased and feed conversion ratios improved as the level of the dietary Azolla meal increased. Survival rates were not affected by the levels of Azolla in the diets.
    • Article

      Survival and growth of bighead carp fry exposed to low salinities 

      LMB Garcia, CMH Garcia, AFS Pineda, EA Gammad, J Canta, SPD Simon, GV Hilomen-Garcia, AC Gonzal & CB Santiago - Aquaculture International, 1999 - Kluwer
      Bighead carp (Aristichthys nobilis Oshima) fry of various ages (11, 18, and 35 days post-hatch) were exposed to the low salinities encountered during the annual intrusion of seawater in Laguna Lake, Philippines. Practical indices of salinity tolerance assessed the effect of a 96 h direct exposure to low salinities (0–16‰). Mean (MST) and median survival times (MST50) of fry decreased as salinity of rearing medium increased. Younger fry were less able to tolerate exposure to these salinities than their older cohorts. Median lethal salinity after 96 h (MLS) revealed higher tolerance among 35–day old fry (7.6‰) than 11 (2.3‰) and 18–day old fry (6.0‰), demonstrating that survival in saline water depends on their age at initial exposure to low salinities. Mean body weight of 18–day old fry reared in 0 and 2‰ for 3 and 4 weeks was higher than for those reared in 4 and 6‰ for the same period. Growth over these periods was inversely related with the range of salinities tested. These results demonstrate that, despite their known stenohalinity, bighead carp fry possess some degree of osmoregulatory capability, allowing them to survive and grow in lakes subjected periodically to saltwater inflow.
    • Conference paper

      Voluntary feed intake and energy partitioning in tilapia, (Oreochromis niloticus) fed diets with different protein/energy levels 

      CB Santiago, U Focken & K Becker - In A Chwalibog & K Jakobsen (Eds.), Energy Metabolism in Animals. Proceedings of the 15th Symposium on Energy Metabolism in Animals, 11-16 September 2000, Snekkersten, Denmark, 2001 - Wageningen Pers
      In order to investigate the effect of different protein/energy levels of diets (two commercial and one laboratory) on voluntary feed intake and energy partitioning in tilapia (O. niloticus), 15 fishes with an initial body mass of 33 g were reared individually in respirometric chambers for 42 days and offered 3 diets ad libitum. The protein contents of the diets were 36.1, 33.8 and 36.8% (dry matter base); the energy content 18.9, 18.4 and 19.2 kJ GE/g and 11.7, 10.5 and 15.4 kJ ME/g. The initial body composition and energy content was estimated from a control group. Feed consumption was recorded for each individual fish. Body mass development was monitored weekly. At the end of the experiment, the fishes were sacrificed and their chemical composition (protein as N.6.25, lipid, ash) and gross energy content were determined. To establish energy budgets, ingestion (I) was calculated from feed intake, retention (P) from accretion in the carcass, heat production (R) from oxygen consumption (indirect calorimetry) and apparently non-utilized energy (faecal and non-faecal losses, U) by difference from energy ingestion.

      In the beginning, food consumption amounted to ~5% body mass equivalent (BME) per day for all groups and gradually decreased to 2.5, 2.8 and 1.6% BME by the end of the experiment. While the food consumption was significantly different between the treatments, there were no significant differences in the body mass development. Average final body mass was 98.6, 93.8 and 103.7 g. Energy retention was 29.7, 29.2 and 44.4% of GE ingested; heat dissipation 32.1, 27.9 and 36.0%; faecal and non-faecal losses 38.2, 43.2 and 19.6%. For all energy budget parameters, values for the laboratory diet were significantly different from those of commercial feeds 1 and 2. Calculation of metabolizable energy from ingested feed revealed no significant differences in the energy uptake, suggesting that the voluntary feed uptake was controlled by the demand for metabolizable energy. The fishes were able to completely compensate for the lower ME content of the commercial feeds by increasing voluntary feed intake.