Abstract
A 22 factorial design (two factors with two levels, in triplicate) was performed to investigate the influence of factors A (soybean oil content in supplemented diet, at 2.1 and 4.2%) and B (time of treatment, 15 and 30 days) in three responses [(a) total n-3 fatty acids; (b) n-6/n-3 ratio; and (c) polyunsaturated fatty acids (PUFA)/saturated fatty acids (SFA) ratio] from lipids of Nile tilapia submitted to experimental treatment. Normality of residuals was assessed through statistical tests. Factors A and B were significant in all obtained regression models, while AB interaction was not a significant contributor for PUFA/SFA response. ANOVA and response surfaces obtained from factorial design indicated best results in tilapia that received the diet containing 4.2% of soybean oil during 30 days.
Highlights
Factorial design is a widely used statistical tool in the scientific community for different samples and purposes due to its simplicity, while allowing interpretation of results considering all involved experimental parameters and providing the effects of possible interactions between selected variables.[1]According to official data, Brazilian fish production was 500000 t in 2011 and tilapia ranked first in this statistic with more than 253000 t.2 Nile tilapia (Oreochromis niloticus) accounts for 40% of the total production from national fish aquaculture
Studies have been done in order to increase omega-3 (n-3) fatty acid contents in muscular tissues of farm-raised tilapia through dietary enhancements with seeds/oils which are rich in polyunsaturated fatty acids (PUFA).[4,5]
The factorial designs which were carried out in order to investigate the amount of n-3 fatty acids, PUFA/saturated fatty acids (SFA) and n-6/n-3 ratios in lipids of Nile tilapia showed significant mathematical models in terms of the studied factors: soybean oil content in feed diet and time of treatment for Nile tilapia
Summary
Factorial design is a widely used statistical tool in the scientific community for different samples and purposes due to its simplicity, while allowing interpretation of results considering all involved experimental parameters and providing the effects of possible interactions between selected variables.[1]According to official data, Brazilian fish production was 500000 t in 2011 and tilapia ranked first in this statistic with more than 253000 t.2 Nile tilapia (Oreochromis niloticus) accounts for 40% of the total production from national fish aquaculture. Brazilian fish production was 500000 t in 2011 and tilapia ranked first in this statistic with more than 253000 t.2. Studies have been done in order to increase omega-3 (n-3) fatty acid contents in muscular tissues of farm-raised tilapia through dietary enhancements with seeds/oils which are rich in polyunsaturated fatty acids (PUFA).[4,5] Significant differences in lipid composition between wild and farm-. According to ANVISA, soybean oil has 19-30% of oleic acid (18:1n-9), 44-62% of linoleic acid (18:2n-6; the most important fatty acid from omega-6 (n-6) series), and 4-11% of linolenic acid (18:3n-3; the most important fatty acid from n-3 series).[7] From a nutritional point of view, the PUFA intake is important to humans, while ingestion of saturated fatty acids (SFA) is associated with increased serum cholesterol level in humans.
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