## 4 Discussion  
Different factors can influence shrimp feed consumption and growth, including the molting phase, feeding frequency, and temperature [40; 41]. Previous studies indicate that low temperatures reduce shrimp growth compared to optimal conditions [42; 43]. This trend was also observed in the present study, where shrimp exposed to 22 \({}^{\circ}\)C showed slower growth compared to studies conducted with _P. vanname_ at optimal temperatures [44; 45]. Moreover, [PERSON] et al. (2023) [46], exposing _P. vanname_ to 20 \({}^{\circ}\)C in a high-density BFT system for 36 days, reported an average growth of 0.37 \(\pm\) 0.05 g per week, which is lower than that observed in our study under lower density and clear water conditions. In the present study, dietary supplementation with the FPE additive appeared to attenuate growth reduction under a suboptimal temperature. The main finding was that shrimp in the STD+1 treatment group showed higher final weight, weekly weight gain, and daily growth coefficient compared to the STD group. FPE at 1 g kg\({}^{-1}\) was sufficient to accelerate shrimp growth, with weekly weight gain increasing by 14.00% and final weight increasing by 11.24% after 12 weeks. Therefore, FPE supplementation at this dose had a positive effect on the growth performance of shrimp reared at 22 \({}^{\circ}\)C. However, increasing the dose from 1 to 2 g kg\({}^{-1}\) did not provide additional benefits under the conditions of this experiment. Low temperatures are known to inhibit carbohydrate and nucleotide metabolism in _P. vanname_, which may lead to increased amino acid utilization and lipid metabolism to meet energy demands [47]. Supplementation with 1 g kg\({}^{-1}\) of FPE, containing amino acids and nucleotides, may have helped address these metabolic needs, although this effect was not enhanced at the higher dose. Crustaceans have complex chemoreceptive structures that are used to identify a range of attractive molecules and are mainly sensitive to water-soluble molecules such as amino acids and nucleotides [17; 48]. The presence of these chemoattractive substances in shrimp  
Figure 3: The cumulative survival after low-salinity shock (2.8 g L\({}^{-1}\) for 24 h) of _Peneus vanname_ reared in clear water at a suboptimal temperature (22 \({}^{\circ}\)C) and fed a diet containing 0 (STD), 1 (STD+1), and 2 g kg\({}^{-1}\) (STD+2) of a functional palatability enhancer (FPE) for 12 weeks. Kaplan–Meier _p_-value = 0.85998.  
feeds can result in higher and/or faster feed consumption, improving growth in two potential ways. A higher feed consumption, energy, and nutrient intake logically leads to higher growth. On the other hand, even if total feed intake is not increased, a faster rate, or speed, of feed consumption leads to the lower leaching of feed nutrients into the water, with consequent improvements in shrimp performance (growth and improved FCR) as well as the farming environment. In our study, the diet supplementation with FPE, rich in amino acids, nucleotides, and flavoring substances with known chemoattractant effects, was able to increase growth, although improvements in feed intake and FCR were marginal and non-statistically significant. This might be explained by the feeding protocol that was followed, where shrimp intake was restricted to the ration established by the feeding table rather than feeding the shrimp ad libitum. The general composition of shrimp feed has changed in recent years, with an increasing inclusion of plant-based ingredients to reduce costs [19; 49]. In the present study, a diet simulating current standard practices was formulated with 12.53% fish meal and 15% poultry viscera meal as animal protein sources, and 31% soybean meal and 16.65% wheat bran as the main plant ingredients. Shrimp can digest a variety of ingredients as sources of nutrients and energy [50], aided by enzymes in the gastrointestinal tract and hepatopancreas, such as \(\alpha\)-amylase, trypsin, and chymotrypsin [51; 52; 53; 54].