Digestive enzyme is responsible for digestive function and nutrition absorption for all animals. A study on enzyme activities is thus providing an in-depth understanding of an animal’s diet and feeding management.
Asst. Prof. Dr. Karun Thongprajukaew’s research on digestive enzyme technology to enhance digestion and nutrition among aqua animals has multiple directions. First is modifying low-nutrition, agricultural/industrial byproducts to have appropriate property for hydrolyzation of the enzyme. An enzyme is extracted from a live organism is texted via an in vitro digestibility to evaluate digestive efficiency. This method is efficient because it mimics the environment inside a tested animal, easy to analyze, low-cost, unaffected by the animal’s preference of food, and can provide comparison between animals of same type of organisms or different ones. The results help select raw materials and cooking method specific to a type of animal and its digestive ability, and offers high efficiency as food is turned into amorphous, no dangerous chemical sediments, and can digest food in large amount.
Byproduct modification methodology is physical such as water submersion, microwave, high-frequency sound wave, gamma ray, electron beam, for example, to break down lignocellulose and crystalized structures in raw material which slow down digestion. The method boasts its high efficiency in transforming raw materials into amorphous structure without any dangerous chemical residues and in large amount.
The second direction focuses on feeding system, food management, and food production that increase growth and allow most optimization of feeding. The research has been experimented with food group such as Oreochromis niloticus, Lates calcarifer, Channa striata, Plectropomus leopardus, Epinephelus coioides x E. lanceolatus, Macrobrachium rosenbergii, in process of studying Sepioteuthis lessoniana; also pet group like Betta splendens, Poecilia reticulate, and in process of studying Carassius auratus.
Knowledge on digestive enzyme increases feeding efficiency for example using ratio of feeding frequency to digestive enzyme activity to identify appropriate feeding frequency that is cost-effective; using starvation technique to clear up digestive tract; and using technique of re-feeding to increase appetite; or compensatory growth following starvation and re-feeding.
In a large-size ecological system, the type of digestive enzyme indicates diversity of food or prey; variety of isoform enzymes indicate rich diversity of food in nature.
In addition to economical aquatic animals, Dr. Karun also studies digestive enzyme in animal waste to improve food management and nursery of the near-extinct green turtle (Chelonia mydas) from the process of hatching to head-started. A joint research conducted with Research and Development of Marine Resources and the Andaman Coast has developed feeding system and food management to allow more than 95% of survival and outstanding growth. Research is being expanded to conserve and restore other types of sea turtles.
Dr. Karun Thongprajukaew informed that enzyme in animal waste can test the change of physiology, biochemistry, and ecology of the animals. These enzymes reside in digestive tract and the waste, some of which has film protection to ease the bowel movement and prevent dispersion of enzyme in water. The clear benefit of this approach is no disturbance or harm to the animals hence appropriate for animals that are near-extinction.
Dr. Karun also expanded the research to other economical animals like silkworm, goat and poultry through collaboration with researchers from other institutions. Future direction includes integration of research knowledge to improve food management of all animal groups “from feedstuff to fork”.