## 1 Introduction  
The accelerated growth of the aquaculture sector is in line with industry forecasts for global food production. This sector aims to increase its production by 10% over the next 10 years by intensifying systems and expanding production areas [1]. As far as marine shrimp production is concerned, climatic changes and temperatures are key success factors [2, 3]. Shrimp farming is practiced worldwide in tropical and subtropical regions. In the native region of _Penaeus vannamei_, on the Pacific coast, temperatures are normally between 24 and 30 \({}^{\circ}\)C [4]. However, owing to its adaptability to different temperatures and salinities, Pacific white shrimp culture is not limited to its region of origin, and it is the most widely farmed shrimp species in the world [5; 6; 7]. Farming has been expanding to subtropical regions where shrimp often face suboptimal temperatures during part of the production cycle and are exposed to temperature fluctuations throughout the year, which reduces productivity, increases susceptibility to pathogens, and leads to slower growth [8; 9]. In addition, many tropical regions suffer from fluctuations in the average rearing temperature due to extreme climatic events such as El Nino, cyclones, and rainy periods [2; 10]. Finding solutions to mitigate the impacts of suboptimal temperatures could bring important benefits to the shrimp farming industry [11; 12; 13; 14; 15]. Marine crustaceans are highly sensitive to chemical signals in the water [16; 17]. These chemical signals control feeding behavior and feed consumption and are used in shrimp farming to increase feeding efficiency and reduce waste, thus decreasing feeding costs and environmental impacts [18]. Conventionally, these compounds are derived from marine animal ingredients such as fish, krill, squid, or mussel meal, which are finite and expensive [19; 20]. In another study [21], the authors found that a mixture of squid visceral powder, fish soluble, squid paste, and shrimp paste, and another mixture of yeast extract, squid visceral powder, squid paste, and shrimp paste, are able to promote higher nutritional intake and a greater antioxidant capacity of _P. vannamei_. However, the use of additives, including alternative sources to marine ingredients, is a convincing and sustainable alternative to improve feed palatability. Other non-marine ingredients that have been tested include microalgae and seaweed, by-products of terrestrial animals, flavorings, and enzymatically treated or hydrolyzed by-products of the food industry [1; 22]. In addition, certain additives can be associated with increased immunity and protection against potential pathogens [23; 24], improved growth and feeding efficiency [25], and increased feed attractiveness and palatability [26; 27], therefore maintaining productivity during colder seasons [28]. Previous studies reported that the use of a concentrated functional palatability enhancer (FPE, Lucta S.A, Madrid, Spain) containing non-animal ingredients had positive effects on the performance of _P. vannamei_ when reared at optimal temperatures (27 to 35 \({}^{\circ}\)C). For instance, [PERSON] et al. (2019) [29] demonstrated that this FPE could be used as an alternative to squid paste in shrimp diets. This product improved the growth performance of _P. vannamei_ by stimulating feed intake and had positive effects on hepatopancreas protease activity and gut morphology at dosages of 1 g kg\({}^{-1}\) and 1.5 g kg\({}^{-1}\)[29]. The same product at dosages of 1 and 2 g kg\({}^{-1}\) improved feed attractiveness and palatability, as well as salinity stress tolerance [30]. The supplementation of shrimp diets with FPE may improve growth performance and immunological status under chronic exposure to a suboptimal temperature (22 \({}^{\circ}\)C). To our knowledge, no previous studies have evaluated this functional palatability enhancer in shrimp under chronic cold conditions.