Effect of replacing dietary fish meal with poultry by-product meal on muscle fatty acid composition and liver histology of Nile tilapia fry, Oreochromis niloticus.


AYDIN B., GÜMÜŞ E., BALCI B. A., Aktop Y., Aksoy A.

FABA 2014 International Symposium on Fisheries and Aquatic Seciences, Trabzon, Turkey, 25 - 27 September 2014, pp.279

  • Publication Type: Conference Paper / Summary Text
  • City: Trabzon
  • Country: Turkey
  • Page Numbers: pp.279
  • Akdeniz University Affiliated: Yes

Abstract

Objective: The objective of this study was to investigate the effect on fatty acid composition and liver histology of Nile tilapia fry when fishmeal is replaced by poultry by-product meal (PBM) as an alternative protein source in tilapia diets.

Methods: Five isoproteic (34% crude protein), isolipidic (9% crude lipid) and isoenergetic (3750 kcal DE g-1) diets formulated in which PBM replaced 0, 25, 50, 75, and 100% of the protein supplied by fish meal. 20 fish were distributed into each of the aquarium (65 L) as triplicate treatments and fed manually to apparent satiation twice daily for 13 weeks. Fatty acids in fish muscle were analyzed by gas chromatography. For this purpose, total lipids were extracted from samples using a method modified from Bligh and Dyer (1959), and then saponified and methylated for fatty acid quantification (Morrison and Smith, 1964). For histological investigations tissue samples from livers were fixed in 10% buffered neutral formalin, dehydrated in ethanol, cleared in xylene and embedded in paraffin. Samples were sectioned (5 μm thick), stained with haematoxylen and eosin and evaluated by light microscopy.

Results and Discussion: There were significant differences in total fatty acid levels of fish carcass from each treatment at the end of the trial. Fatty acid analysis showed that n-3 PUFA and n-3/n-6 ratio in fish muscle significantly decreased, but SFA were not changed with the increased dietary PBM. MUFA and n-6 PUFA in fish muscle significantly increased with the increased dietary PBM. Histological analysis demonstrated that there were no differences among the treatments. The livers of fish fed the experimental diets exhibited normal-shaped hepatocytes but, a slight low hepatic lipid deposition at all treatments.

Key Words: Oreochromis niloticus, fish meal, poultry by-product meal,  fatty acids, liver histology