FEEDING RESPONSES OF WHITE-LEGGED SHRIMP Penaeus vannamei TO VARYING RATIOS OF BREWERY SPENT GRAIN (BSG) AND YEAST (BSY) WITH OR WITHOUT BSG SPONTANEOUS FERMENTATION

Introduction

The cost and availability of protein ingredients is a challenge for the development of the aquaculture feed sector, especially in developing areas .  As a result,  ingredient such as brewery spent grains (BSG) and yeast (BSY) constitute an interesting option. BSG  has been the focus of several  nutritional studies since the 90’ with various results (1) . T he high-water content (75-85%) of BSG  when  exiting the brewery limits its use  due to  the heterogenous mastering of drying process in factories (2 ).  Then, spontaneous fermentation as a low-cost conservation method seems to be an interesting opportunity. BSY have been  widely studied for their role in boosting immunity. However, their interest as a palatability and attractiv ity enhancer remains little studied. Therefore, th is  trial aims to determine whether the fermentation state of BSG influence feeding behaviour of shrimp depending on the BSY/BSG ratio.

 Material & methods

The behavioural trial aims to  study whether  feed attractivity and palatability  are influenced by the state of  fermentation of BSG and by the ratio BSG/BSY following a factorial design described in Table 1. 35 shrimp will be distributed in 7 , 50 L  reserve  tanks with 5 shrimp per tank. 7 isoproteic (17,4%) experimental feeds containing a neutral base and 30% of BSG and BSY mixture will be crafted.  During 5 days,  shrimp  will be presented  by group of five to the feeds in a tank dedicated to behavioural studies equipped with cameras. Each group is only presented to a feed once a day and is never presented to the same feed twice.

Recorded videos will then be analysed with an AI based tracking software to generate data on palatability and attractiveness based on parameters such as prehension speed, time spent in the feeding zone, shrimp activity. Feed consumption will also be monitored. Data will then be analysed via statistical analysis.

Objectives

 Experiments assessing ingredient attractivity and palatability took place in April 2025. The growth trial  started  the end of April  2024 and will end in  June 2025. These experiments will help to fill the data gap while providing information on the interest of BSG and BSY for aquafeed.

1.  Steinberg, et al. « Fermentation Residues and Miscellanies: ‘What Else to Offer?’ ». In Aquatic Animal Nutrition: Plant Preparations , edited by Christian E.W. Steinberg, 359 88. Cham: Springer Nature Switzerland, 2024. (https://doi.org/10.1007/978-3-031-70938-8_6.

2.  Robertson, et al. « Profiling brewers’ spent grain for composition and microbial ecology at the site of production ». LWT - Food Science and Technology 43, no 6 (1 juillet 2010): 890 96. (https://doi.org/10.1016/j.lwt.2010.01.019.