Watchariya Purivirojkul

Growth, nonspecific immune characteristics, and survival upon challenge with Vibrio harveyi in Pacific white shrimp (Litopenaeus vannamei) raised on diets containing algal meal

A 70-day growth trial was conducted with postlarvae 12 (PL12) Pacific white shrimp (Litopenaeus vannamei) to study the suitability of soybean meal and oil originating from a single-celled microorganism (thraustochytrid) as fishmeal and fish oil substitutes in practical diets for L. vannamei. The growth, survival rate and immune characteristics were evaluated. Seven experimental diets were designed with soybean meal used as the primary protein source; each formulation contained 33% crude protein and 8% lipid. Fish oil was completely substituted with 3% soybean oil and meals originating from single-celled heterotrophs rich in docosahexaenoic acid (DHA) and arachidonic acid (ARA) were added at different concentrations. A commercial shrimp feed was used as the control diet. The final weights and survival rates of the shrimp were not significantly different among all treatments. However, shrimp raised on diets supplemented with marine algal meals rich in DHA and ARA showed significant improvement in immune parameters, such as total hemocyte count, phenoloxidase activity, superoxide dismutase activity, and bactericidal activity. Additionally, the survival rate after challenge with Vibrio harveyi was increased. These findings demonstrated that substitution of thraustochytrid-derived meals as an alternative to fish-based ingredients in shrimp diets provided similar growth rates while increasing the immune parameters and providing vibriosis resistance.

A New Species of Tetraphyllidean (Onchobothriidae) Cestode from the Brown-Banded Bambooshark Chiloscyllium punctatum (Elasmobranchii: Hemiscylliidae)

Abstract: Yorkeria chonburiensis n. sp. (Tetraphyllidea: Onchobothriidae) is described from the spiral intestine of a specimen of the brownbanded bamboo shark, Chiloscyllium punctatum, collected from the Gulf of Thailand, Chon Buri Province, Thailand. Yorkeria chonburiensis n. sp. is distinguished from all other species of Yorkeria by the pattern of proglottids (craspedote as opposed to acraspedote) and the proglottid number (more than 168). The new species is larger than all other members of Yorkeria, and the medial hooks are slightly larger than the lateral hooks with a ratio of 1:1.87–1:1.96. The position of the genital pore is 29–34% from the anterior margin of proglottid, greater than all other members of Yorkeria.