We investigated the effects of fadrozol, an aromatase inhibitor (AI), and 17a-methyltestosterone (MT) on the induction of sex change in juvenile longtooth grouper Epinephelus bruneus, via histological observation of gonads. Changes in the mRNA expression of GtH subunits (FSH-b and LH-b) in the pituitary, and estradiol-17b (E2) and 11-ketotestosterone (11-KT) levels in the blood were also surveyed after AI and MT treatment. Juvenile longtooth groupers (113917 g body weight; 16.291.2 cm body length) received intramuscular injections of AI at 3 (3-AI) and 5 (5-AI) mg/kg BW doses and MT at a 5 mg/kg BW (5-MT) dose. At week 7 post-injection, 3-AI and 5-MT oocytes were degenerated, and gonads of the 5-AI group initiated spermatogenesis. At week 21 post-injection, 3-AI-and 5-MT-treated gonads contained spermatogonia and spermatocytes, while 5-AI treatment induced advanced stages of spermatogenesis. The serum E2 level showed no significant differences throughout the experimental period, whereas that of 11-KT was significantly elevated in the 5-AI group at weeks 7 and 21 post-injection. A significant increase in the expression of FSH-b mRNA was evident in the 5-AI group at week 21 post-injection. In contrast, LH-b mRNA expression did not significantly differ among groups during the experimental period. These results imply that sex change has two stages in the longtooth grouper. In the first stage, oocytes are degenerated by the stimulation by 11-KT, and in the second stage spermatogenesis occurs, owing to the co-effects of 11-KT and FSH-b.

Sixty [(Duroc×Yorkshire)×Landrace] pigs (7.63±0.41kg average body weight and 25-d average age) were used in a 20-d growth assay to determine the effect of dietary recombinant human lactoferricin culture (RHLC) supplementation on growth performance, digestibility and plasma IgG concentration in weaning pigs. Dietary treatments included 1) Negative control (NC : without antibiotic), 2) Positive control (PC : NC diet + 0.1% chlortetracycline), 3) RHLC0.3 (NC diet + 0.3% RHLC), 4) RHLC0.5 (NC diet + 0.5% RHLC). No differences were found among treatments in average daily gain (P 0.05). ADFI of pigs fed RHLC0.3 diet was higher than that of pigs fed PC diet (P 0.05). However, pigs fed RHLC0.5 diet had improved gain/feed compared to pigs fed PC diet. Pigs fed PC and RHLC diets showed significantly increased dry matter digestibility compared to pigs fed NC diet (P 0.05). There was no significant difference in plasma IgG concentrations (P 0.05). The supplementation of RHLC in starter pig diets appears to be an alternative to antibiotics.

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This study was conducted to analyze the difference of body types within and between wild and farmed populations of olive flounder Paralichthys olivaceus using measured records of morphological traits. The results showed that surveyed traits and standard deviation were 1,355±742 g of body weight, 48.01±7.79 cm of total length, and 40.96±6.80 cm of body length. Also body height, body shape index and condition factor were 17.19±3.43 cm, 9.99±0.74 and 11.16±1.54, respectively. As result of least squares mean and standard error for each trait assumed in this study, those of farmed population showed significantly higher than those of wild population in all traits, exclusively in total length and body length (p<0.01). Particularly, the values of the body height and the body weight of the farmed population were higher than those of the wild population in the same total length. And the phenotypic correlation coefficients of the body weight, the total length, the body length and the body height showed strong positive correlation in all populations. These result suggested that morphological differences exist in farmed and wild flounder. Therefore, introduction of wild flounder is essential for the future production to improve the body type of farmed flounder, and parental fish should be chosen by considering selection of commercially important traits in the production process.

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