Penaeus vannamei is one of the most bred crustacean species in the world. In farms, feed is, by far, the main expenditure. Feed and premix manufacturers aim to find affordable but attractive formula. However, the methods for measuring the attractivity of a feed remain poorly reproducible. One solution is to design a test arena and a standardised procedure allowing to automatically track shrimp during a feeding event and assess pellet attractivity. In this test arena, lowering the level of stress is paramount not to bias their feeding behaviour. In a previous study, we showed that the use of orange light induced less stress behaviours in shrimps than other colours (Pichon et al., in prep).
The objective of this study is to test the effect of prior familiarisation with the test arena on stress and feeding behaviour during the testing phase.
Thirty PL20 P. vannamei shrimp were divided into two groups of fifteen shrimp: the test group and the control group. The test group was familiarised with the test arena 1h per day over three consecutive days and was tested the following week. The control group was tested without prior familiarisation to the test arena. Each group consisted of five batches of three shrimp. The batches were randomly tested (once per day) with: no food, blank diet, blank diet + 0.5% KS50 or blank diet +1% KS50. KS50 is a functional amino acids mix obtained from poultry feather by the company BCF Life Sciences.
At the beginning of a test, the batch of shrimp was first acclimatised 15 min in the starting zone, they were then given access to the whole test arena and filmed for 20 min. The food was gently placed in a petri dish at the opposite of the starting zone, called the feeding zone (FZ), 1min before the end of the acclimation period. We measured shrimp’s stress (loops and tail flips) and feeding (latency to reach the FZ, time spent in the FZ and number of transitions to the FZ) behaviours.
Careful evaluation of the effects of the different features of the test arena (e.g., light) and procedure (e.g., familiarization, acclimation, …) on stress behaviours will provide important insights to design a standardised procedure. This will allow an accurate assessment of feed attractivity in shrimp.