Lipid metabolism in Yellowtail Kingfish

Investigate lipid metabolism in Yellowtail Kingfish fed different energy diets, with and without an emulsifier at winter water temperatures.

Yellowtail Kingfish - Brian Gratwicke (CC BY 2.0)

Yellowtail Kingfish  - Brian Gratwicke [CC BY 2.0 

The aim of this project is to understand the effects of different energy levels and emulsifiers on the liver and pyloric caeca health and lipid metabolism of Yellowtail Kingfish.

In fish, dietary energy is the second growth limiting factor, after dietary protein, which should ideally be satisfied by dietary lipids.

Yellowtail Kingfish grow out diets previously contained 20% crude lipid (Stone and Bellgrove, 2013). Based on recent research however, Stone et al. (2016) suggested that Yellowtail Kingfish may be fed a higher lipid (~30-35%) diet during summer water temperatures to improve growth.

Temperate water marine fish species, including Yellowtail Kingfish, may be less tolerant to high lipid diets when exposed to low water temperatures.

To improve lipid digestion and absorption in the gastrointestinal region of Yellowtail Kingfish, an emulsifier may be included in the diet. However, the effect of different energy levels (lipid levels) and emulsifiers on lipid metabolism and digestion of Yellowtail Kingfish is unknown.

Key methodology:

Investigating two factors (2 × 2):

  • Factor one, emulsifier (no emulsifier and emulsifier)
  • Factor two, lipid level (high [30%] and low [20%]).

Twenty fish will be measured, weighed and stocked into one of the three replicate 5000 L tanks treatment combination-1 (n = 4 treatments; n = 12 tanks). Tanks will be supplied with partial flow-through/recirculating (100% system water exchange d-1), sand filtered, UV treated sea water at ambient temperature.

Fish will be fed to apparent satiation at 9:00 h daily for a total of 84 days. At the conclusion of the study, fish will be histologically sampled for pyloric caeca and liver histology.

Both aspects will improve our knowledge of lipid metabolism in Yellowtail Kingfish fed dietary energy (lipid) levels and inclusions of emulsifiers.


Tagged in Honours projects - Animal science, Honours in Animal Science subtheme - Animal and veterinary bioscience, Honours projects - David Stone, Honours projects - Gordon Howarth, Honours projects - Todd McWhorter