32 MARCH 2025 • WORLD AQUACULTURE • WWW.WAS.ORG enriched rotifers from 2 to 14 dph, with the RS treatment receiving 50% less than the Control. AF Artemia was introduced from 10 to 14 dph, followed by enriched Artemia from 15 to 21 dph. Different dry diets were used: The Control group received competitor feed from 14 dph onwards. The RS group received the Natura® line from 2 dph onwards (see Figure 3). The trial concluded at 21 dph with the first grading. Biometric measurements In the first trial using a backyard production system, biometric measurements were conducted every 5 days starting from 5 dph, comparing growth rates. Between 10 and 20 larvae per tank were sampled to assess body development and total length (Figure 4). In the second trial using an advanced production system, measurements were taken every 5–7 days, starting from 2 dph, with 10 to 30 larvae observed and measured throughout the trial (Figure 4). A salinity stress test was performed in both trials to assess stress resistance before grading. Growth, survival rate, fish size distribution, and feed consumption were evaluated at 25 dph for Trial 1 using the backyard production system and at 21 dph for Trial 2 using the advanced production system. Results Larvae readily ingested Natura pRo® <100 from its first application. Figure 5 illustrates their high acceptance of the feed from the beginning. Significant differences in the total length of larvae fed the Natura diet were observed starting at 15 dph (p < 0.01) and 21 FIGURE 3. Experimental conditions and feeding protocols used for the backyard (BRIN) system in Trial 1 and for the advanced (SFA) fish production system used in Trial 2. dph (p < 0.01) in Trial 1 using the backyard production system. In Trial 2, the effect of the Natura protocol did not show significant differences compared with Control (Figure 4). Survival rates in the Natura treatment were 22% higher in Trial 1 using the backyard production system and 10% higher in Trial 2 using the advanced production system. Rotifer substitution was successful, with a 69% reduction in Trial 1 and 45% in Trial 2 (Figure 6). FIGURE 4. Total length of the juvenile barramundi reared in the backyard production system at 5-25dph in Trial 1 (left) and in the advanced production system used in Trial 2 at 2-25dph (right). FIGURE 5. Two-day-old (above) and three-day-old (below) barramundi larvae feeding on Natura pRo® <100.
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