Effect of Agricultural By-Products as a Carbon Source in a Biofloc-Based System on Growth Performance, Digestive Enzyme Activities, Hepatopancreas Histology, and Gut Bacterial Load of <i>Litopenaeus vannamei</i> Post Larvae

The present study evaluated the influence of different commercial agricultural by-products as a carbon source in a bifloc-based (BFT) culture system on growth performance, whole-body proximate composition, digestive enzyme activities, gut microbial abundance, and hepatopancreas histology of Pacific whiteleg shrimp, Litopenaeus vannamei post larvae (Pls). Three groups were designed, the first group was the control group, where the shrimp was reared in clear water (without carbon source addition and water exchange rate of 100% two times a week) and fed with a commercial diet, in the second and third groups shrimp were reared in BFT systems using two different carbon sources, sugarcane bagasse (SB) and rice bran (RB) without additional feeding or water exchange. The initial stocking density was 16 Pls/liter with an average individual shrimp weight of 0.01 ± 0.002 g and age (PL20). The experiment lasted 90 days. The water quality parameters were maintained at optimum levels during the experiment. The final body weight and specific growth rate of shrimp were significantly (p ≤ 0.01) higher in the control group than those reared in both SB and RB-based BFT. Meanwhile, the survival rate was significantly (p p p < 0.05) higher in BFT groups. Furthermore, the hepatopancreas histological status of shrimp reared in the SB-based BFT group showed an increase in the hepatopancreas tubules in the distal and B-cell zones (blister-like cells) by 16.83 and 34.89%, respectively, compared to the control. This study revealed that BFT could be used as a natural feed without artificial diets, which influenced the gut microbiota of shrimp, increased digestive enzyme activities, as well as improved the histological structure of the hepatopancreas of shrimp. However, the success of this conditions under high stocking density still needs more investigation

Xenogenesis-Production of Channel Catfish × Blue Catfish Hybrid Progeny by Fertilization of Channel Catfish Eggs with Sperm from Triploid Channel Catfish Males with Transplanted Blue Catfish Germ Cells

<p>Putative spermatogonia A from a fresh-cell isolate or a density-gradient-centrifuged isolate from the testes of Blue Catfish <i>Ictalurus furcatus</i> were transplanted into the gonads of triploid Channel Catfish <i>I. punctatus</i>. The cells were introduced into gonads of the host via catheterization (2 × 10⁴–1.43 × 10⁶ cells) or by surgically inserting the cells directly into the gonad (7 × 10⁴–1.25 × 10⁵ cells). Ten months after implantation, DNA was analyzed from biopsies of the gonads and seven of eight males were found to be xenogenic, having Blue Catfish cells in their gonads. The xenogenic males successfully courted normal Channel Catfish that had been induced with hormones to ovulate, but none of the eggs hatched, indicating inadequate sperm production, an inability to ejaculate, and/or low sperm quality. Male xenogenic catfish treated with luteinizing hormone releasing hormone analog had well-developed testes, and sperm production was detected in three of seven xenogenic males examined 2 years after transplantation. Sperm were removed from a male that had been surgically transplanted with Blue Catfish cells and used to fertilize eggs from a hand-stripped Channel Catfish female. One percent of these eggs hatched. All seven surviving 6-month-old progeny of this male had the external morphology, swim bladder shape, nuclear DNA profile, and mitochondrial DNA profile of female Channel Catfish × male Blue Catfish F₁ hybrids, indicating that this triploid Channel Catfish male produced Blue Catfish sperm. This is the first report of successful production of xenogenic catfish and the first report of producing 100% hybrid progeny using xenogenesis in fish.</p> <p>Received March 23, 2016; accepted July 23, 2016 Published online November 18, 2016</p