Effect of dietary cornstarch levels on growth performance, digestibility and microscopic structure in the white shrimp, Litopenaeus vannamei reared in brackish water

Abstract

The ability of Litopenaeus vannamei (initial mean weight: 0.96 ± 0.02 g) to utilize different levels of cornstarch was examined in terms of growth indices, body composition, digestibility and microscopic structure of the hepatopancreas. Six isonitrogenous semipurified diets were fed to satiation to shrimp for 8 weeks in triplicate tanks (30 shrimps per tank) connected to a natural brackish water (6–8 g L−1) recirculating system. Diets contained different levels of cornstarch (100, 150, 200, 250, 300 and 350 g kg−1) as the source of carbohydrate and were balanced using cellulose. Weight gain (WG), survival rate and feed conversion rate (FCR) were considerably affected by cornstarch levels of diets. The highest WG (453.6 g kg−1) and best FCR was observed in shrimp fed the 150 g kg−1 (cornstarch level) diet and was significantly (P < 0.05) higher than those fed diets containing 250–350 g kg−1 cornstarch. However, the survival rate reached maximum in shrimp fed the 100 g kg−1 diet (96.7), some 30% higher than the lowest rate, which was found in shrimp fed the 250 g kg−1 diet. Body lipid tended to be higher in shrimp fed diets with higher cornstarch levels. The apparent digestibility of dry matter and crude fat increased with increasing levels of cornstarch and, hence, decreasing levels of cellulose. In addition, histological study on shrimp fed 10–350 g kg−1 diets exhibited histological changes. The overall conclusion was that the optimum cornstarch level may be set at 100–200 g kg−1 when the diets contain 380 g kg−1 protein.

Effect of dietary cornstarch levels on growth performance, enzyme activity and hepatopancreas histology of juvenile red swamp crayfish, Procambarus clarkii (Girard)

“…There would be an increasing lipid accumulation in the whole body and hepatopancreas associated with enhanced levels of dietary cornstarch. Similar results were obtained by Guo et al (2006).…”

“…Shiau and Peng (1992) found that P. monodon fed with a diet containing 100 g kg −1 of starch grew more efficiently. Guo et al (2006) indicated that the maximum growth rate of Litopenaeus vannamei was achieved in shrimps fed with diets containing 100-200 g kg −1 of cornstarch. In the present study, it was found that P. clarkii fed with diets containing 200 g kg −1 of cornstarch showed the best growth performance and feed utilization.…”

“…In the present study, it was found that P. clarkii fed with diets containing 200 g kg −1 of cornstarch showed the best growth performance and feed utilization. The ability of different shrimp species to utilize carbohydrate may depend on the ability to oxidize the glucose from the digestion of carbohydrate, and to store the excess glucose as glycogen or fat (Guo et al, 2006).…”

“…Thus, diet containing lower level of cornstarch may result in low feed intake for animals, which can be an important factor leading to poor growth. It has been reported that up to a certain level, growth of crustaceans increases proportionally when dietary carbohydrate content rises (Guo et al, 2006;Zhang et al, 2009). However, when dietary carbohydrate levels exceeded an optimum, animals cannot exhibit a further increment in growth because excessive dietary carbohydrate may decrease the ability to digest, absorb and assimilate dietary carbohydrate, even going so far as to reduce the feed intake.…”

“…Few studies have been conducted to determine the effect of types and levels of carbohydrates on crustaceans (Andrews et al, 1972;Guo et al, 2006;Rosas et al, 2000Rosas et al, , 2001Zhang et al, 2009). In Penaeus monodon Fabricius juveniles, survival was affected by carbohydrate levels, and trehalose promoted better growth than sucrose and glucose (Alava and Pascual, 1987).…”