Armando C. Fermin

Diet development and evaluation for juvenile abalone, Haliotis asinina: animal and plant protein sources

Growth studies were conducted to determine the suitability of animal and plant protein sources in the diet of abalone, Haliotis asinina. Juvenile abalone with mean initial weight and shell length of 0.69±0.04 g and 11.4±0.35 mm, respectively, were fed practical diets for 84 days at a temperature range of 28–31 °C. The practical diets contained 27% crude protein from various sources such as fish meal (FM), shrimp meal (SM), defatted soybean meal (DSM), and Spirulina sp. (SP). A formulated diet (diet 1) served as the control. The diets were fed to abalone at 2–5% body weight once daily at 1600 h. Weight gain (WG), increase in shell length (SL), specific growth rate (SGR), protein efficiency ratio (PER) and feed conversion ratio (FCR) were evaluated. Highest weight gain (WG: 454%) was attained with abalone fed diet 2 with protein sources coming from a combination of FM, SM, and DSM. This value was, however, not significantly different (P<0.05) from those fed diets 4 and 1 (Control diet) with protein sources coming from FM, SM, SP and FM, DSM, SM, respectively. Abalone fed diet 3, which used both plant protein sources, DSM and SP, showed significantly lower WG (327%). Survival was generally high ranging from 85% to 100% for all treatments. The SGR showed the same trend as the percent weight gain. The FCR and PER obtained, however, were not significantly different for all treatments. The amino acid profile of diets 1, 2, and 4 simulated that of the abalone protein, which could have been a contributing factor to the higher growth rate of abalone fed these diets. Diet 3, which contained only plant protein sources, showed relatively lower methionine values compared with the abalone muscle tissue. Although abalone are considered herbivorous animals, results of this study indicate that a combination of dietary plant and animal protein sources was necessary to attain the best growth rate.

Antibacterial activity of tilapia Tilapia hornorum against Vibrio harveyi

Abstract Disease due to luminous Vibrio has been a major problem of the shrimp industry. Different technologies have been introduced to control the disease. One of the techniques reported to work against luminous bacteria in the Philippines is the green water culture system (or finfish–shrimp integrated culture system). A green water culture system is an innovative technique wherein shrimp are cultured in water collected from a pond where tilapia or other fish species are grown. In some cases, the fish are cultured in an isolated net pen inside the shrimp culture pond. This study clarifies the effect of one component of the green water culture system, the presence of all male tilapia ( Tilapia hornorum ) on luminous bacteria Vibrio harveyi . Results showed that stocking tilapia at a biomass not lower than 300 g/m 3 efficiently inhibited the growth of luminous bacteria in shrimp (biomass=80 g/m 3 ) rearing water without the growth of microalgae.

LHRH-a and domperidone-induced oocyte maturation and ovulation in bighead carp, Aristichthys nobilis (Richardson)

Effects of intraperitoneal injections of LHRH-a and domperidone (DOM), given singly or in combination at two injections, on oocyte maturation, ovulation and spawning in bighead carp, Aristichthys nobilis, were investigated. Results were compared with the existing protocol using HCG + LHRH-a at 1800 IU and 20 μg/kg BW, respectively, to induce spawning in bighead carp. Oocyte diameter of fish at 6 h after the second injection of LHRH-a + DOM and HCG + LHRH-a had significantly increased to 7.0% and 7.5% respectively, as compared to the 0 h group (P<0.05); fish injected with LHRH-a, DOM or saline had significantly lower increases (1.0%, 2.0%, and 3.0%, respectively). Ovulation was induced in 75% and 60% of fish injected with LHRH-a + DOM and HCG + LHRH-a, respectively. In contrast, fish treated with LHRH-a, DOM or saline did not ovulate. Total eggs spawned, and fertilization and hatching rates did not differ significantly (P<0.05) between the two groups with ovulated fish. Although injection protocols using LHRH-a + DOM and HCG + LHRH-a were equally effective in inducing spawning of bighead carp, the former had a lower combined cost than the latter.

Effects of different illumination levels on zooplankton abundance, feeding periodicity, growth and survival of the Asian sea bass, Lates calcarifer (Bloch), fry in illuminated floating nursery cages.

Abstract The effects of different illumination levels on Zooplankton abundance and feeding periodicity, growth and survival of hatchery-produced Asian sea bass, Lates calcarifer, fry in illuminated floating net cages were determined in a 35-day experiment. Zooplankton abundance (consisting mainly of copepods at 64–78% of total abundance in all cages) was highest in cages illuminated at 180 lx (mean: 124 individuals l−1) and at 300 lx (mean: 405 individuals l−1) and peaked at 0400. High prey densities subsequently resulted in increased fish feeding as evidenced by the greatest number of prey (mean: 416–462 individuals fish−1) found in their guts between 0400 and 0800. Feeding incidence (range: 84–89%) was generally higher among fish held in illuminated cages than those reared in dark cages (67%). Low feeding of fish held in dark cages eventually led to starvation and mass mortality. The present results indicate that a light intensity of at least 300 lx attracts the highest number of Zooplankton and promotes the best weight specific growth rate (10% day−1) and survival (40%) in sea bass juveniles reared in illuminated nursery cages.

Grow-out culture of tropical abalone, Haliotis asinina (Linnaeus) in suspended mesh cages with different shelter surface areas

Thisstudy investigated the effects of shelter surface area (SSA) on the feeding,growth and survival of the donkey-ear abalone, Haliotisasinina reared in mesh cages (0.38×0.38×0.28m) suspended in flow-through tanks (water volume = 6m3). Cages had sections of polyvinylchloride (PVC) thatprovided shelters with surface area of 0.22 m2, 0.44m2 and 0.66 m2.Hatchery-produced abalone with initial shell length of 32 ± 1mm and wet weight of 7.5 g were stocked at 50individuals cage−1 that corresponded to stocking densities ofca. 227, 113 and 75 abalone m−2 of SSA. The ratios of sheltersurface area to cage volume (SSA:CV) were 5.5, 11 and 16.5. Abalones wereprovided an excess red seaweed Gracilariopsis bailinae(= Gracilaria heteroclada) at weekly intervals overa 270-day culture period. Feeding rates (18–20% of wet weight), foodconversion ratio (26–27) and percent survival (88–92%) did notdiffer significantly among treatments (p > 0.05). Body size at harvest rangedfrom 56 to 59 mm SL and 52 to 57 g wet body weightwith significant differences between abalone reared at SSA 0.22m2 and 0.66 m2 (p < 0.05).Abalone reared in cages with 0.66 m2 SSA grewsignificantly faster at average daily growth rates of 132 μm and188 mg day−1. Stocking densities of 75–113m−2 SSA in mesh cages suspended in flow-throughtanks resulted in better growth of abalone fed red seaweed.