Category Archives: Aquatic Species Nutrition

“Temperature effects on growth, feeding rate and feed conversion of the Pacific white shrimp (Penaeus vannamei)” (Wyban et al 1995)

Citation: Wyban, J., Walsh, W., and Godin, D. (1995). “Temperature effects on growth, feeding rate and feed conversion of the Pacific white shrimp (Penaeus vannamei).” Aquaculture, 138(1-4), pp. 267-297. DOI: 10.1016/0044-8486(95)00032-1

Summary By: Alexandra Pounds

Image Credit: Flickr

  • Big Picture: As shrimp grow, the optimum temperature for growth decreases. Different sized shrimp require different temperatures for optimum growth. FCR was more related to shrimp size than to temperature, where smaller shrimp had better FCRs.
  • This experiment tests the effects of temperature on juvenile growth rate, feeding rate, and feed conversion.
  • Methods:
    • 4 experiments: 4 different temperatures, 3 different stocking sizes
    • Indoor laboratory setting (recirculating system), big enough to allow room for normal swimming behaviour
    • System, water quality, flow rates, photoperiod, and feed were standardized across all tanks
    • Shrimp were stocked at 50 shrimp / m3
    • Feed consumption was calculated by feed supplied minus residual feed (visually estimated feed at bottom of tank)
    • Used pond water (and sea water at the end to test if there was a difference)
    • Temperature was measured twice daily
    • Statistics used: one-way ANOVA, orthogonal contrast, and multivariate F-tests
  • Results:
    • Shrimp grew bigger and ate more with warmer temperatures.
    • FCR depended on stocking size, but not temperature. FCR was inversely related to size: Larger shrimp had less efficient FCRs.
    • Smaller shrimp ate more food at all temperatures.
    • Optimum temperature was size-specific. Large shrimp had optimum temperature of 27 deg C, while small shrimp (<5g) had an optimum temperature of over 30 deg C.
      • Reduced feeding & growth below 23 deg C for all sizes
      • Reduced feeding & growth above 30 deg C for large shrimp
      • Optimum temperatures for growth:
        • Small shrimp: >30 deg C
        • Medium shrimp: 30 deg C
        • Large shrimp: 27 deg C
      • Optimum temperatures for lowest FCR:
        • Small shrimp: FCR unaffected by temperature
        • Medium shrimp: 27-30 deg C
        • Large shrimp: 27 deg C
      • As shrimps get bigger, they become less efficient at growth and more sensitive to temperature
  • Limitations
    • Dissolved oxygen (DO) was not constant across tanks, as dissolved oxygen is lower when temperatures are higher. However, DO was always above 90% saturation.

“Effect of probiotics on growth performance and digestive enzyme activity of the shrimp Penaeus vannamei” (Wang 2007)

Citation: Wang, Y. (2007). “Effect of probiotics on growth performance and digestive enzyme activity of the shrimp Penaeus vannamei.” Aquaculture, 269(1-4), pp. 259-264. DOI: 10.1016/j.aquaculture.2007.05.035

Summary By: Alexandra Pounds

Image Credit: Flickr

  • Big Picture: Shrimp receiving probiotics grew bigger and had better digestion than those without probiotics; however, higher concentrations of probiotics did not result in bigger shrimp.
  • This study investigated whether adding probiotics to shrimp’s diet would affect their growth and ability to digest food.
  • Other studies have found that β-glucans, lipopolysaccharides, peptidoglycans and probiotic bacteria can help boost the immunity of shrimp, but did not look at growth.
  • Probiotics were added to the food at different concentrations.
    • Probiotics used: Photosynthetic bacteria and Bacillus sp. (grown in the lab)
    • Concentrations used: T-1, 2 g kg 1 (1 g kg 1 lyophilized photosynthetic bacteria cells (PSB) and 1 g kg 1 lyophilized Bacillus sp. (BS)); T-2, 10 g kg 1 (5 g kg 1 PSB and 5 g kg 1 BS); and T-3, 20 g kg 1 (10 g kg 1 PSB and 10 g kg 1 BS).
  • Methods:
    • 28 days
    • 3 replicate groups for a total of 12 tanks were used.
    • Shrimp were fed 3 times per day with the same pellets, with different additions of probiotics.
    • water quality was kept the same for all the tanks.
    • Shrimp started out at the same size.
  • Results:
    • Shrimp receiving probiotics grew better than the control (no probiotics).
    • Shrimp receiving different concentrations of probiotics did not show any differences in growth.
    • T-2 and T3 had the best digestion (based on enzyme activity levels)
    • Probiotics did not seem to affect water quality.

“Growth, digestive activity, welfare, and partial cost-effectiveness of genetically improved farmed tilapia (Oreochromis niloticus) cultured in a recirculating aquaculture system and an indoor biofloc system” (Luo et al 2014)

Citation: Luo, G., Gao, Q., Wang, C., Liu, W., Sun, D., Li, L., and Tan, H. (2014). “Growth, digestive activity, welfare, and partial cost-effectiveness of genetically improved farmed tilapia (Oreochromis niloticus) cultured in a recirculating aquaculture system and an indoor biofloc system.” Aquaculture, 422-423, pp. 1-7. DOI: 10.1016/j.aquaculture.2013.11.023

Summary by: Alexandra Pounds

Image Credit: Flickr

  • Big Picture: Tilapia in the biofloc system grew bigger and had a lower FCR than tilapia in traditional RAS. Further, biofloc systems was more cost-effective than the RAS.
  • This experiment compared a biofloc system (BFT) with a traditional recirculating aquaculture system (RAS) to find out which was more profitable.
  • Both BFT and RAS recycle water so that farming can take place on land. RAS typically discharges waste, whereas BFT tries to reuse the waste to feed biofloc in the system. This reduces waste, but requires more aeration to keep the biofloc suspended and oxygen levels high. It also works better with hardy filter feeders like shrimp and tilapia, because biofloc can be hard on gills due to the higher suspended solids in the water. This bacteria can help remove nitrogen from the system.
  • Methods:
    • Disolved oxygen, pH, temperature, and water levels were kept constant and equal within both systems.
    • GIFT tilapia was used in both tanks at 8.06 kg/m3 stocking density. They were all fed the same commercial pellets at 2% of biomass daily. Fish were fed 3x per day.
    • Sodium acetate was added to the BFT system at 75% of feed to maintain required Carbon to nitrogen ratio for bacterial health. Biofloc was also removed regularly, as fish did not eat enough of it to maintain the system.
    • The systems were run for 87 days.
  • Physical Results:
    • Both systems removed nitrogen waste sufficently.
    • The BFT system allowed for more efficient uptake of nitrogen and phosphorous, because the N & P in the biofloc is fed back into the fish when they eat the biofloc, instead of being removed from the system as waste.
    • No fish died in either system, and welfare parameters were no different between the systems.
    • There was no difference in lipid or protein content of the fish upon harvest; however, the biofloc system did not meet lipid requirements of tilapia.
    • Individual BFT fish were 22% heavier on average than individual RAS fish.
    • The FCR of BFT fish (1.2) was 18% better than the FCR of the RAS fish (1.47).
    • BFT fish had greater levels of metalloenzymes SODs, which shows that the BFT fish had stronger immue systems.
  • Cost comparison:
    • Energy & depreciation cost was greater for RAS because the RAS needed additional equipment to remove waste.
    • Carbon sources and aeration added to the BFT were the biggest cost in that system.
    • BFT was more cost effective than RAS.

“Fatty acids of wild and cultured Penaeus vannamei larvae from Ecuador” (Motano & Navarro 1996)

Citation: Montano, M., and Navarro, J. (1996). “Fatty acids of wild and cultured Penaeus vannamei larvae from Ecuador.” Aquaculture, 142, pp. 259-268.

Summary by: Alexandra Pounds

Image Credit: Wikimedia Commons

  • Big Picture: Wild larvae are more resilient than cultured larvae fed on artemia, probably because wild larvae have diets that have higher levels of long-chain PUFA.
  • Wild postlarvae are more resilient than cultured. Wild caught larvae have higher survival rates. In fish, resilience is associated with higher levels of omega-3 PUFA (poly-unsaturated fatty acids), mainly, EPA and DHA. This study asked if it was the same with shrimp.
  • Methods:
    • Larvae were collected from 5 sites along the coast of Ecuador throughout the summer. Larvae from the hatchery were also collected. This resulted in three separate groups:
      • Cultured larvae
      • Early summer (cold) wild larvae
      • Late summer (hot) wild larvae
    • The researchers extracted lipids from these larvae for analysis.
  • Results:
    • Wild larvae from the colder months had significantly higher DHA, EPA, and 16:1 levels.  Wild larvae from the warmer months had significantly higher saturates and 18:2 omega-6 PUFA.
    • There were no differences in arachidonic acid, monoenes, 18:3 omega-3, and the ratio of DHA to EPA (DHA:EPA) over the different months.
    • Wild larvae had significantly higher levels of EPA, DHA, 16:0, 16:1, 18:0, DHA:EPA, and saturated fatty acids than cultured larvae.
    • Cultured larvae had higher levels of 18:3 omega-3, 20:4 omega-6, 18:2 omega-6, 18:1, and monoenes.
    • Origin of wild larvae had no effect on lipids.
  • Implications:
    • Higher temperatures cause higher levels of saturated fatty acids, whereas colder temperatures cause higher levels of unsaturated fatty acids.
    • Wild larvae had higher levels of PUFAs than cultured, probably due to diet. Cultured larvae are fed enriched artemia, which has more linolenic acid. Linolenic acid was 15 times higher in cultured larvae than wild larvae.
    • The results suggest that, as in fish, shrimp larvae that are cultured with artemia and have lower levels of long-chain PUFAs are less resilient.