Using cornstarch in microparticulate diets for larvicultured tropical gar (Atractosteus tropicus)

Abstract

Aquaculture in Mexico has been developed by the cultivation of commercial species. In Tabasco, the cultivation of native species is mainly limited by the lack of nutrition studies to support its crop profitability. Among these species is the tropical gar (Atractosteus tropicus), which has great potential for cultivation. However, the nutritional value of carbohydrates in diets for this species which contribute to improved growth and survival, have not been evalulated,. Thus, in the present investigation, isoprotein and isolipid diets have been designed based on the substitution of cellulose by corn starch (D1: 0% starch-15% cellulose, D2: 7.5% starch-7.5% cellulose and D3: 15% starch-0% cellulose) and compared with a commercial trout diet (45% protein and 16% lipids). A total of 1800 larvae (0.008 ± 0.002 g and 10.5 ± LT 0.126 mm) were used, distributed in a recirculation system in order to evaluate growth and survival for 30 days. The results show higher growth and survival of 97% of larvae fed the D3 diet, while cannibalism in the species was mitigated. Major digestive enzyme activities occurred (acid protease, alkaline protease, trypsin, chymotrypsin, leucine aminopeptidase, carboxypeptidase A, lipase, α-glucosidase and amylase) for larvae fed D3. It is concluded that the contribution of corn starch (15%) replacing cellulose in the diet improves growth and survival of this species.

Use of Potato Starch in Diets of Tropical Gar (Atractosteus tropicus, Gill 1863) Larvae

“…Differences between these results can be attributed to many factors, including differential utilization of the dietary source of carbohydrates (digestion and metabolism), level included in the diet, differences in the balance of macronutrients, complexity of the carbohydrate source [11,12] and even possible differences between egg quality between spawning batches due to the limited information on nutritional requirements of broodstock in the species. Nevertheless, the same findings of acceptance and utilization of corn starch as energy source [4] and potato starch (present study) make it clear that A. tropicus larvae show a common pattern of higher growth with increasing starch levels. Hence, differences in survival can be attributed to differences in carbohydrate solubility and limitations of the carbohydrase enzyme battery to digest different starch sources [13], in conjunction with cannibalism behavior.…”

“…However, a combined feeding strategy (Artemia naupli, live Artemia and the experimental diets mix) was used until day 14 [3], whereas experimental feeds in the present study were used as sole feed from the time of first opening of the mouth and anus. Another study on the same species that tested corn starch as a carbohydrates source with two inclusion levels (7.4% and 15.4%), following the same feeding strategy (experimental diets offered from opening of mouth and anus) as the present study, showed comparable growth rates with those reported here, although reduced cannibalism and higher survival were reported [4]. Differences between these results can be attributed to many factors, including differential utilization of the dietary source of carbohydrates (digestion and metabolism), level included in the diet, differences in the balance of macronutrients, complexity of the carbohydrate source [11,12] and even possible differences between egg quality between spawning batches due to the limited information on nutritional requirements of broodstock in the species.…”

“…Previous studies indicate that the use of carbohydrates in formulations depends on the type and concentration included, the fish species and growing conditions, which can promote greater digestibility, improving the level of food intake and consequently growth and larval survival [4,10]. Prior studies of A. tropicus larvae using diets based on rendered proteins (poultry byproduct and pork), showed higher growth and survival than results of the present study.…”

“…Previous studies evaluated diets with different levels of corn starch [4], and found higher digestive enzyme activities (proteases, lipases and carbohydrases) with increasing starch levels in the diet (up to 15%) in A. tropicus larvae. The present study used higher starch levels (up to 28%), and inclusion of 16% and 22% of potato starch yielded the highest activity values for proteases (alkaline proteases, trypsin, chymotrypsin and leucine aminopeptidases).…”

Effect of β-Glucans in Diets on Growth, Survival, Digestive Enzyme Activity, and Immune System and Intestinal Barrier Gene Expression for Tropical Gar (Atractosteus tropicus) Juveniles

“…However, the production of this species has been limited by the lack of studies regarding the development of specific foods that allow maximizing their growth and survival and increasing production on a commercial scale [1]. For this reason, several studies on A. tropicus have focused on maximizing the production performance of the species [2], developing balanced foods based on digestive physiology [3], and improving the growth and utilization of nutrients [4,5]. On the other hand, health impacts due to outbreaks of diseases under culture conditions generate large economic losses [6]; therefore, to reduce this impact, the use of immunostimulants could enhance the immune response and increase resistance of the organism against infectious diseases [7].…”