A team of researchers in Brazil examined the use of mealworm meal (MM) in the diet of farmed shrimp as a potential replacement protein for fishmeal.
The group published its work in the journal Aquaculture.
- Mealworm was evaluated for its potential as a future alternative protein source to fishmeal.
- This study compares the digestibility of mealworm at different inclusion levels for Pacific white shrimp.
- Methionine was the first limiting amino acid in mealworm for the Pacific white shrimp.
- Performance was not affected when fishmeal was totally replaced by mealworm.
“The objective of this present study was to determine apparent digestibility coefficients of mealworm meal when used as a feed for shrimp juveniles L. vannamei and its effect on growth and on chemical composition of the shrimp body,” said the researchers.
The group found that farmed shrimp preformed similarly when receiving diets using fishmeal or mealworm meal. There were differences in shrimp lipid content but not in relation to protein levels.
“The performance of L. vannamei was not affected by replacing fishmeal with mealworm meal in the diets utilized in the present study,” said the researchers. “However, the use of MM should be supplemented by methionine to meet the L. vannamei amino acids requirements.”
Pacific white shrimp accounted for about 80% of the farmed shrimp in the world in 2014. The amount in production is expected to increase in coming years.
However, growth in shrimp farming has put pressure on the supply of fishmeal, rendering it a costly ingredient, said the authors. As such, there is interest in establishing alternative dietary proteins that could be used in shrimp feed, they said.
Insects, according to the UN's Food and Agricultural Organization (FAO), have potential as high-protein feed ingredients.
Depending on life stage and species, they can provide good sources of proteins, lipids, minerals, vitamins and energy, while requiring little land or water and the potential to recycle forms of organic waste.
“Tenebrio molitor, a beetle species of the Tenebrionidae family, better known as the mealworm (in its larval stage), is a promising source of alternative proteins and is already being produced on an industrial scale,” said the researchers. It offers high amounts of crude protein and low ash content along with levels of vitamins and minerals, they added.
The insect has been used in poultry diets to replace soybean meal or fishmeal. It also has been tested for use as a fishmeal alternative in diets for farmed rainbow trout, European sea bass, common catfish and tilapia.
However, while in general the nutritional quality of insect proteins is described as “good,” the potential as an alternative feed source is dependent upon digestibility and amino acid profile, said the researchers.
Methods and materials
In the study, 450 shrimp were given one of five trial diets for a period of 42 days, said the researchers. Diets were made with commercially available mealworms.
The test diets replaced fishmeal at 0%, 25%, 50%, 75% or 100% with mealworm meal, they said. At the end of the feeding period, shrimp were collected, weighed and analyzed.
Researchers calculated weight gain, specific growth rate, daily feed intake, feed conversion rate, protein retention efficiency, and survival rate, said researchers. Shrimp were checked for crude protein, crude lipid, crude fiber, moisture, gross energy and essential amino acids.
Additionally, researchers completed a digestibility study using a reference diet and an experimental diet. The control diet included 330 g kg-1 digestible protein and 3,000 kcal kg-1 of digestible energy, and the test diets included 845g kg-1 of the control diet with 150g kg-1 mealworm meal and 5g kg-1 chromic oxide as a marker.
Fecal samples were collected twice daily, and were assessed for the apparent digestibility coefficients (ADC) for dry matter, crude protein, energy and amino acids, they said.
The apparent digestibility coefficients of dry matter and energy had low values, but the protein ADC had a value of 76.1 and the essential amino acid values ranged from 72.86% to 86.41%, said the researchers. The first limiting amino acid was found to be methionine.
Similar growth results were found for shrimp getting all of the diets, they said. “Weight gain, specific growth rate, feed intake, feed conversion, survival and protein retention were not affected by replacing fishmeal with MM for all the percentages used."
Protein content of the shrimp was the same for all diets, but moisture content decreased linearly as fishmeal was removed from the diet, they said. However, lipid content increase from 1.13% to 1.88% with additional amounts of MM in the diet.
“Mealworm meal has not been previously evaluated as a dietary protein source for shrimps, but the growth parameters evaluated in this experiment exhibited satisfactory results with respect to the replacement diets,” they said. “A regression test showed that when fishmeal was totally replaced by MM, there was no negative effect on any of the growth parameters evaluated.”
Title: Potential use of mealworms as an alternative protein source for Pacific white shrimp: Digestibility and performance
Authors: R Panini, L. Freitas, A. Guimarães, C. Rios, M. da Silva, F. Vieira, D. Fracalossi, R. Samuels, E. Prudêncio, C. Silva, R. Amboni,