Palatability of Protein Hydrolysates from Industrial Byproducts for Nile Tilapia Juveniles

The Promising Role of Synthetic Flavors in Advancing Fish Feeding Strategies: A Focus on Adult Female Zebrafish (Danio rerio) Growth, Welfare, Appetite, and Reproductive Performances

The present study aimed to test over a six-month period different synthetic flavors in zebrafish (Danio rerio) as an experimental model. Specifically, two attractive and one repulsive synthetic flavors were added (1% w/w) to a specific zebrafish diet, which was administered to the fish during the whole life cycle (from larvae to adults), to evaluate their physiological responses, emphasizing fish welfare, feed intake, growth, reward mechanisms, and reproductive performances. Fish welfare was not affected by all tested flavors, while both attractive flavors promoted fish feed ingestion and growth. The results were supported by both molecular and immunohistochemical analyses on appetite-regulating neurohormonal signals, along with the influence of the feed hedonic properties induced by the brain reward sensation, as demonstrated by the dopamine receptor gene expression. Finally, the present study demonstrated that a higher feed intake also had positive implications on fish reproductive performances, suggesting a promising role of synthetic flavors for the aquaculture industry. In conclusion, the results highlighted the potential of synthetic flavors to improve fish feeding strategies by providing a consistent and effective alternative to traditional stimulants, thereby reducing dependence on natural sources.

The Application of Synthetic Flavors in Zebrafish (Danio rerio) Rearing with Emphasis on Attractive Ones: Effects on Fish Development, Welfare, and Appetite

The aim of the present study was to test synthetic flavors as potential feed attractants in zebrafish (Danio rerio) during early development. Six experimental groups were set up in triplicate: (i) a CTRL group fed a zebrafish commercial diet; (ii) a PG group fed a control diet added with Propylene Glycol (PG); (iii) A1+ and A2+ groups fed a control diet added with 1% of the two attractive flavors (A1+ cheese odor made by mixing Propylene Glycol (PG) with the aromatic chemicals trimethyamine, 2-acetylpyrazine, 2-acetylpyridine, and dimethyl sulfide; and A2+ caramel odor, made of PG mixed with the aromatic chemicals vanillin, maltol, cyclotene, acetoin, butyric acid, and capric acid with traces of both gamma-octalactone and gamma-esalactone) or the repulsive flavor (A- coconut odor, made by mixing PG with the aromatic chemicals gamma-eptalactone, gamma-nonalactone, delta-esalactone, and vanillin with trace of both delta-octalactone and maltol), respectively; (iv) an ROT group fed the two attractive diets, each administered singularly in a weekly rotation scheme. All the tested synthetic flavors did not affect the overall health of larval and juvenile fish and promoted growth. Due to the longer exposure time, results obtained from the juvenile stage provided a clearer picture of the fish responses: zebrafish fed both attractive diets showed higher appetite stimulus, feed ingestion, and growth, while the brain dopaminergic activity suggested the A2+ diet as the most valuable solution for its long-lasting effect over the whole experiment (60-day feeding trial, from larvae to adults). The present study provided important results about the possible use of attractive synthetic flavors for aquafeed production, opening new sustainable and more economically valuable opportunities for the aquaculture sector.

Recent Advances, Challenges, Opportunities, Product Development and Sustainability of Main Agricultural Wastes for the Aquaculture Feed Industry – A Review

Million tonnes of agricultural waste are generated annually worldwide. Agricultural wastes possess similar profiles to the main products but are lower in quality. Managing these agricultural wastes is costly and requires strict regulation to minimise environmental stress. Thus, these by-products could be repurposed for industrial use, such as alternative resources for aquafeed to reduce reliance on fish meal and soybean meal, fertilisers to enrich medium for growing live feed, antimicrobial agents, and immunostimulatory enhancers. Furthermore, utilising agricultural wastes and other products can help mitigate the existing environmental and economic dilemmas. Therefore, transforming these agricultural wastes into valuable products helps sustain the agricultural industry, minimises environmental impacts, and benefits industry players. Aquaculture is an important sector to supply affordable protein sources for billions worldwide. Thus, it is essential to explore inexpensive and sustainable resources to enhance aquaculture production and minimise environmental and public health impacts. Additionally, researchers and farmers need to understand the elements involved in new product development, particularly the production of novel innovations, to provide the highest quality products for consumers. In summary, agriculture waste is a valuable resource for the aquafeed industry that depends on several factors: formulation, costing, supply, feed treatment and nutritional value.

Effects of Replacing Fishmeal and Soybean Protein Concentrate with Degossypolized Cottonseed Protein in Diets on Growth Performance, Nutrient Digestibility, Intestinal Morphology, Cecum Microbiome and Fermentation of Weaned Piglets

Simple Summary

Highly digestible and high-quality proteins are especially needed in weaned pigs to alleviate weaning stress in piglets. Fishmeal (FM) and soybean protein (SPC) are two commonly used protein supplements in the diets of weaned pigs, but the high prices of those two kinds of ingredients have prompted a search for an alternative cost-effective protein source. After the removal of anti-nutritional factors, degossypolized cottonseed protein (DCP) shows potential as an alternative to FM and SPC. In this study, the effects on weaned piglets of replacing FM and SPC with DCP in diets were evaluated. The results showed that replacing FM with DCP weakens the small intestinal morphology and decreases nutrient digestibility, but improves the community structures of cecum microbiota that relieve these negative effects without impairing the growth performance of weaned piglets.

Abstract

The inclusion of high-quality proteins is commonly used in swine production, especially in weaned pigs. Our research investigated the effects of replacing fishmeal (FM) and soybean protein concentrate (SPC) with degossypolized cottonseed protein (DCP) on the growth performance, nutrient digestibility, intestinal morphology, cecum microbiota and fermentation in weaned pigs. A total of 90 pigs were used in a 4-week trial. Pigs were randomly assigned to three dietary treatments (initial BW 8.06 ± 0.26 kg; six pigs per pen; five pens per treatment), including a basal diet group (CON) with a 6% SPC and 6% FM; two experimental diets group (SPCr and FMr) were formulated by replacing SPC or FM with 6% DCP, respectively. There were no differences in growth performance and diarrhea rate among three treatments except for the ADFI during day 14 to day 28. Using the DCP to replace FM would weaken the jejunum morphology and decrease the nutrient digestibility of pigs during day 0 to day 14. However, replacing FM with DCP can improve the community structure of cecum microbiota, and may relieve these negative effects. In conclusion, DCP can be used as a cost-effective alternative protein supplement.

Obtención y evaluación de concentrado proteico hidrolizado de residuos animales como alternativa de alimentación en Piaractus brachypomus (Cuvier 1818)

En la industria acuícola, se vienen desarrollando acciones encaminadas a buscar fuentes proteicas alternativas palatables y de alto valor biológico para reemplazar las fuentes convencionales. Debido al potencial nutricional de los subproductos animales, se han adoptado tecnologías para su uso, como las técnicas de bioconversión por hidrólisis enzimática. En consecuencia, el objetivo de este estudio fue obtener y evaluar un concentrado de proteína hidrolizada de residuos animales (CPHRA) como alternativa en dietas para Piaractus brachypomus. Las vísceras de los subproductos avícolas se evaluaron utilizando ácido fórmico y vísceras de trucha al 20% para promover la hidrólisis enzimática a un pH más bajo (pH 3,66). El producto resultante se utilizó en la formulación de dietas para determinar coeficiente de digestibilidad aparente (CDA) de energía y nutrientes, utilizando una dieta control () y tres dietas con inclusión de 10%, 20% y 30% de CPHRA (T1, T2 y T3). Se alimentaron por triplicado ciento veinte juveniles de híbridos de cachama blanca con un peso promedio de 145 ± 3,0 g. La CPHRA presentó alto contenido proteico y se evidenciaron diferencias significativas (p < 0,05) para los CDA de materia seca, proteína bruta, grasa bruta, energía bruta y absorción de cenizas, calcio y fósforo. Los CDA de nutrientes y energía estaban por encima del 80%. En consecuencia, el concentrado de proteína hidrolizada de los desechos de aves de corral tiene un gran potencial como alternativa proteica y energética de alto valor nutricional en la alimentación de los peces.