ẢNH HƯỞNG CỦA CÁC MỨC BỔ SUNG KHOÁNG VÀO THỨC ĂN ĐẾN KẾT QUẢ NUÔI VỖ ỐC BƯƠU ĐỒNG (Pila polita Deshayes, 1830)

This study aimed to evaluate the effects of mineral supplementation in feed on the reproductive efficiency of black apple snail (Pila polita) during maturity cultivation. Snail broodstocks (height: 37.5 - 42.6 mm/ind; equivalent to 75 days of age) were reared in the tarpaulin tanks (1 × 1 × 1m) at a density of 60 ind./tank (the ratio of male: female was 1: 1). The food was supplemented with Pro Mix minerals at five different levels: (1) Control without Pro Mix supplementation (No.Mi-F); (2) 3% minerals (Mi3-F); (3) 5% minerals (Mi5-F); (4) 7% minerals (Mi7-F) and (5) 9% minerals (Mi9-F). After 120 days of culture, the Gonadosomatic Index (GSI) of snails was highest in Mi5-F (6.50% in female; 14.1% in male) and significantly different (P <0.05) compared to No.Mi-F (3.66%; 6.10%). In Mi7-F treatment, the broodstocks showed spawning frequency of 1.00 clutch/week/m2 and a fecundity of 0.53 clutch/female, followed by Mi5-F (0.92 clutch/week/m2; 0.49 clutch/female) and were different (P <0.05) from the No.Mi-F treatment (0.65 clutch/week/m2; 0.35 clutch/female). The study results indicated that the addition of Pro Mix to feed at a level of 5% minerals significantly enhanced GSI and the reproductive efficiency of the black apple snails.