Have you ever wondered what makes shrimp feed palatable to shrimps?
Shrimp’s Chemosensory System
Like humans using tongues and noses to provide us with senses of taste and smell, shrimp possess chemoreceptors to help them detect chemical signals that help them find their food.
In particular, shrimps possess three special chemoreceptors at different parts of their body: antennular chemoreceptors, leg chemoreceptors, as well as mouth chemoreceptors.
Antennular chemoreceptors are in charge of searching out and orientating the shrimp towards any incoming chemical stimuli, while leg chemoreceoptors stimulates local grasping reflexes in response to the stimuli. Finally, mouth chemoreceptors take control of the decision of the shrimp to ingest the food in response to the chemical stimuli.
What Makes Shrimp Feed Palatable?
What makes a shrimp feed palatable to the shrimps? Particular molecules and compounds in feed components elicit a strong feeding behaviour upon interaction with the shrimps’ chemoreceptors – which immensely aids in the palatability of the feed. Studies have identified these compounds as free amino acids within the shrimp feed, and the availability of these amino acids depend largely on the type of protein used.
Molecules that elicit a positive response upon interaction with these chemoreceptors will aid in palatability of the feed. In other words, nutritious feed components are what makes the feed appealing to the shrimps.
Which leads us back to the topic of protein in shrimp feed yet again. How does shrimp feed made with black soldier fly (BSF) protein perform in terms of palatability?
Shrimp Feed with Black Soldier Fly protein
The key amino acids identified as attractant compounds have been shown to be significantly higher in concentration within shrimp feeds with BSF larvae meal replacement, as compared to traditional shrimp feed using only fishmeal as a protein source (Lee & Myer, 1997; Oteri et. al., 2021).
Examples of such amino acids include hydroxyproline, glycine, arginine, glutamic acid and alanine, which also play key roles in the maintenance of the shrimps’ bodily systems. In a way, you can also say that nutrition is directly related to how appetising the feed is to the shrimp!
Other Factors Determining Palatability
When you or I are faced with stress or undesirable situations, we tend to lose our appetite. It’s the same for shrimp!
Aside from feed properties, the aquatic environment is also key in determining the attractiveness of the feed. Parameters such as pH (water acidity) and salinity (dissolved salt content) can greatly affect the shrimps’ appetites, hence it is also important to keep those in check. A study done by Fernandez (1995) showed that L. vannamei shrimps feed best between the pH of 7.0 to 9.0, and within the salinity range of 15% to 25%. On the other hand, the shrimps’ feed intake decreases by as much as 50% at the pH of 6.0 and 10.0, which may be an indicator of environmental stress.
Shrimp can sense protein meal from black soldier fly larvae when it is in their feed. They are strongly attracted to it because they can tell that the proteins are exactly what they need to grow.