Evaluation of canola meal as an aquafeed ingredient for barramundi (Asian seabass; Lates calcarifer)

Ngo, Diu Thi (2014) Evaluation of canola meal as an aquafeed ingredient for barramundi (Asian seabass; Lates calcarifer). Masters (Research) thesis, James Cook University.

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Canola meal (CM) is one of many potential plant ingredients for fishmeal replacement in fish diets. Many fish species have performed good growth when fed with dietary CM. However, there is limited information for using this ingredient in barramundi. In order to use this ingredient for aquaculture feeds, the information such as nutritional value, nutrient digestibility and ingredient utilisation have to be provided. Therefore, the present study described in this thesis was carried out to: (1) characterise nutritional composition and determine nutrient and energy digestibility of four Australian CMs with respect to different origin and processing method; (2) assess effects of diets with serial inclusion levels of two different CMs regarding different processing methods (expeller and solvent extraction) on growth performance and feed utilisation; (3) examine effects of CMs on changes in plasma chemistry, histology of digestive, metabolic organs and hepatic gene expression.

To achieve the above objectives, two experiments were undertaken. The first experiment (digestibility experiment) was designed with six diets (four CMs: three solvent extracted (SE) CMs from Newcastle, Footscray, Numurkah and one expeller extracted (EX) CM from Pinjarra), a diet with fishmeal (FM) as the sole protein and a diet based on lupin kernel meal (LM) were included as reference diets. Each CM test diet and LM diet were made by incorporation of 30 % of test ingredient and 70 % of basal mash (FM reference). Dry matter, protein, energy, amino acid and yttrium content of the diets, ingredients and faeces were analysed to enable the determination of the apparent digestibility of corresponding parameters. The second experiment (growth experiment) included eight dietary treatments each with three replicates, one FM reference diet (sole protein as fishmeal) (FM), one lupin (LM) diet (300 g/kg LM) and the CM diets (100, 200, 300 g/kg as either SE CM or EX CM). Performance indices such as feed intake, weight gain, DGC, FCR, protein and energy retention were determined. Following, an examination of the health effects and molecular responses of fish fed the CM containing diets compared to the FM and LM diets were also carried out. Plasma samples were analysed for biochemical parameters. The liver, kidney, caeca, distal intestine and stomach were used for histological analysis. For molecular expression, genes involved in fatty acid metabolism (FAS, SCD and FXR) and energy production pathways (CS and PDK) and others involved in detoxification (CYP1A1, CYP3A, CYP2N, GST, GHGPx and GPx) were examined using RT-qPCR. The relative expression level of each gene in each sample was determined by normalising the cycle threshold values for each gene to Ef1-α.

Compositional analysis of the ingredients showed that the protein content of the SE CMs (370 to 423 g/kg DM) was higher than that of the EX CM (348 g/kg DM), but the lipid content was lower than that of the EX CM. Among the SE CMs, the protein digestibility of the CMs from Numurkah and Newcastle was similar (84.1 % and 86.6 % respectively), corresponding to that of the LM but significantly higher than that of the CM Footscray (74.5 %). The protein digestibility was the lowest (63.1 %) for the EX CM. The energy digestibility of the CMs (43.1 % to 52.5 %) was similar to that of the LM (54.8 %) except for the lower of the SE CM Footscray (32.4 %). The SE CMs provide 276 to 366 g/kg DM of digestible protein while that of the EX CM is only 220 g/kg DM. The digestible energy content of the SE CM Footscray (6.5 MJ/kg) was significantly lower than that of other CMs (8.7 to 10.6 MJ/kg DM).

After an eight week culture period the feed intake, growth performance, and protein retention efficiency of fish fed with dietary CM levels were similar or even higher to those of fish fed the FM and the LM diets. The FCR is also similar or better than the control diets. The exception to this was for fish fed with the 300 g/kg EX CM diet. The diet containing 300 g/kg EX CM depressed growth performance, feed intake, and increased FCR. In general, the SE CM can be used up to 300 g/kg diet without negative growth effects while 200 g/kg is the maximum acceptable level of the EX CM for barramundi.

Plasma biochemistry parameters were fairly similar among each of the dietary treatments. There were no modifications in the morphology of the liver, kidney, caeca, distal intestine or stomach of fish caused by any of the experimental diets. The expression of genes involved in fatty acid metabolism and TCA cycle was not influenced by fish fed with CM containing diets relative to the FM control and LM diets. However, fish fed with the diet containing 300 g/kg EX CM were shown to downregulate the expression of some genes acting in detoxification pathways (Lc CYP1A1, Lc CYP3A, Lc CYP2N and Lc GST), but not Lc GPx, Lc PHGPx and Lc GR.

Overall, this study demonstrates that CM is a promising plant ingredient for FM replacement in barramundi based on determined digestible values and feed utilisation. However, implications regarding different origin and processing method importantly affect CM utilisation for barramundi.

Item ID: 41354
Item Type: Thesis (Masters (Research))
Keywords: aquaculture; aquafeed; Asian seabass; barramundi; canola feed; canola meal; digestibility; feed utilization efficiency; feeding and feeds; fish diet; giant perch; growth performance; Lates calcarifer; nutrition; plant protein; rapeseed meal
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Publications arising from this thesis are available from the Related URLs field. The publications are:

Ngo, Diu Thi, Pirozzi, Igor, and Glencross, Brett (2015) Digestibility of canola meals in barramundi (Asian seabass; Lates calcarifer). Aquaculture, 435. pp. 442-449.

Date Deposited: 01 Dec 2015 05:12
FoR Codes: 07 AGRICULTURAL AND VETERINARY SCIENCES > 0704 Fisheries Sciences > 070401 Aquaculture @ 100%
SEO Codes: 83 ANIMAL PRODUCTION AND ANIMAL PRIMARY PRODUCTS > 8301 Fisheries - Aquaculture > 830102 Aquaculture Fin Fish (excl. Tuna) @ 100%
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