ผลของอาหารเสริมสาหร่ายไส้ไก่ (Ulva intestinalis Linnaeus) ต่อการเจริญเติบโตและสีเปลือกของกุ้งขาว (Litopenaeus vannamei Boone, 1931)

Abstract

Marine algae are interested in supplementation in diet for marine shrimp culture for the purpose that it may be benefit to the shrimp growth and may enhance the cooked shrimp color. The effects of gut weed, Ulva intestinalis, supplemented in the diet for rearing the Pacific white shrimp, Litopenaeus vannamei was conducted to study in this research. The diets of 40% protein and 10% lipid were prepared with six different concentrations (0, 6, 12, 18, 24, and 30%) of gut weed, Ulva intestinalis powder. The experimental diets were given to post larvae-30 shrimp (mean initial body weight of 0.12±0.01 g). The experimental shrimp were fed six times a day to apparent satiation with water exchanging every week and weighting at every 2 weeks. After a 12-week cultivation period, the highest final body weight (12.27±0.84 g) and the highest final length (10.97±0.27 cm) was shown in the shrimp fed with 0% gut weed diet (control). During 0-8 weeks, the gained weight of the control group was higher than the shrimp fed with other diets supplemented with gut weed. During 0-2 weeks, the highest specific growth rate (11.75±0.12 % day-1) was presented in the shrimp fed with 0% gut weed supplemented diet and decreased following shrimp culture increased period. Daily feed intake of the shrimp fed with 30% gut weed supplemented diet was the highest throughout the experiment, as well as the feed conversion rate was also the highest. The protein efficiency ratio of the shrimp fed with 0% gut weed supplemented diet was higher than those fed with other supplemented diets during 0-12 weeks. There was no statistical difference in the survival rate of all experimental groups, except at weeks 2-4 and 8-10. At week 2-4, the highest survival rate (80.79±10.33 %) was expressed in the shrimp fed with 6% gut weed supplemented diet, as well as it (92.31±7.69%) was presented in this group at week 8-10. This was higher than those shrimp fed with others. After 12 weeks of shrimp rearing, the shrimp carcass quality was analyzed and the result was 65.68-69.70 % protein, 2.81-3.20 % fat, 6.53-6.80 % fiber, 10.36-7.29 % moisture, and 12.87-10.89 % ash. After rearing, some minerals such as calcium and iron were different in the experimental groups. The calcium content in the shrimp fed with 12-24% gut weed supplemented diet was higher than those fed with other gut weed supplemented diets, while the iron content was lower in the shrimp fed with over 18% gut weed supplemented diets. In the color intensity of cooked shrimp after rearing, the result was that the redness (a*) (p<0.05) in the shrimp fed with gut weed supplemented diets decreased after boiling, while there was no significantly differences in the brightness (L*) and the yellowness (b*), except the shrimp fed with 30% gut weed supplemented diet. However, there was significantly decreased in the yellowness (b*). This study concluded that the supplementation of gut weed, Ulva intestinalis, in the diet of post larva-30 Pacific white shrimp (Litopenaeus vannamei) resulted in decreased growth and the redness of the cultured shrimp after cooked.