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Ontogenic Development of Digestive Enzymes in Mealworm Larvae (Tenebrio molitor) and Their Suitable Harvesting Time for Use as Fish Feed

1
Department of Agriculture, Faculty of Science and Technology, Nakhon Si Thammarat Rajabhat University, Nakhon Si Thammarat 80280, Thailand
2
Department of Applied Science, Faculty of Science, Prince of Songkla University, Songkhla 90112, Thailand
3
Hatyaiwittayalai School, Songkhla 90110, Thailand
*
Author to whom correspondence should be addressed.
Insects 2020, 11(6), 393; https://doi.org/10.3390/insects11060393
Received: 18 May 2020 / Revised: 13 June 2020 / Accepted: 15 June 2020 / Published: 26 June 2020
Mealworm larvae (Tenebrio molitor) are edible insects consumed in feed and food. In the current study, the optimal harvesting time of mealworm larvae for use as aquafeed was investigated during the ages of 30–90 days after hatching (DAH). Development of digestive enzymes, proximate composition, and in vitro protein digestibility using digestive enzymes from African catfish (Clarias gariepinus) and Nile tilapia (Oreochromis niloticus), were used as criteria. The specific activities of pepsin and trypsin significantly decreased with age (p < 0.05) from the first harvesting time until 50 and 45 DAH, respectively, while steadiness in these enzyme activities was observed onwards. Chymotrypsin specific activity appeared constant across all harvesting times. The specific activity of amylase significantly decreased in the later stages of development, while cellulase exhibited a different pattern suggesting it has a major role in dietary fiber utilization relative to starch. Regarding proximate compositions of the mealworm larvae, the moisture and ash contents decreased significantly with age, while the protein content exhibited the opposite trend with the highest contents from 60 to 90 DAH. Crude lipid was generally fairly constant, but its lowest value was observed in the earliest stage. In vitro protein digestibility was not significantly different across all harvesting times for both fish species, except for the significantly decreased digestibility value at 65 DAH relative to 30 and 35 DAH for Nile tilapia. However, based on the economic benefits of time for growth increment and proximate chemical composition, approximately 60 DAH is proposed as suitable for harvesting mealworm larvae to be used in fish feed. View Full-Text
Keywords: economic fish; harvesting time; in vitro digestibility; live feed; proximate composition economic fish; harvesting time; in vitro digestibility; live feed; proximate composition
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MDPI and ACS Style

Rodjaroen, S.; Thongprajukaew, K.; Khongmuang, P.; Malawa, S.; Tuntikawinwong, K.; Saekhow, S. Ontogenic Development of Digestive Enzymes in Mealworm Larvae (Tenebrio molitor) and Their Suitable Harvesting Time for Use as Fish Feed. Insects 2020, 11, 393. https://doi.org/10.3390/insects11060393

AMA Style

Rodjaroen S, Thongprajukaew K, Khongmuang P, Malawa S, Tuntikawinwong K, Saekhow S. Ontogenic Development of Digestive Enzymes in Mealworm Larvae (Tenebrio molitor) and Their Suitable Harvesting Time for Use as Fish Feed. Insects. 2020; 11(6):393. https://doi.org/10.3390/insects11060393

Chicago/Turabian Style

Rodjaroen, Somrak, Karun Thongprajukaew, Puridet Khongmuang, Saowalak Malawa, Kimhun Tuntikawinwong, and Suktianchai Saekhow. 2020. "Ontogenic Development of Digestive Enzymes in Mealworm Larvae (Tenebrio molitor) and Their Suitable Harvesting Time for Use as Fish Feed" Insects 11, no. 6: 393. https://doi.org/10.3390/insects11060393

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