Prebiotic,probiotic, and synbiotic in the diet of Nile tilapia post-larvae during the sex reversal phase

This study evaluated the use of the prebiotic Active-MOS® (mannanoligosaccharides—Biorigin®) and two probiotics: PAS-TR® (Bacillus subtilis and Bacillus cereus var. toyoi—Imeve®) and Bioplus 2BC® (1.6 × 10¹⁰ UFC g^?1 de Bacillus subtilis and 1.6 × 10¹⁰ UFC g^?1 Bacillus licheniformis—Christian Hansen®) tested separately and together, in the diet of Nile tilapia post-larvae during the sex reversal phase. The experiment was conducted in two stages: (i) a total of 2160 3-day-old post-larvae (PL) (10.39 ± 0.85 mm and 12.28 ± 3.15 mg) were used and distributed in 24 tanks of 40 L each (3.0 PL L^?1). Growth performance, chemical analysis of carcass, bacterial recovery, and histomorphometry of intestinal villi were evaluated; (ii) 240 tilapia (4.28 ± 0.19 cm and 1.19 ± 0.09 g) from the previous experiment were used and stocked at 10 PL per aquarium. The parameters evaluated were survival and relative protection level after bacterial challenge against Aeromonas hydrophila. Six treatments with four replications in a completely randomized design were used for both experimental stages. Additives in the diet of tilapia post-larvae did not determine significant differences in growth, survival, microbiological, or histomorphometric parameters in this study. Nevertheless, after the experimental infection, advantages on the use of the additives were observed in terms of higher relative protection levels (38.10%) and relative percent survival in fish receiving Active-MOS® + Bioplus 2BC®. Therefore, we recommend the use of synbiotic (Active-MOS® + Bioplus 2BC®) in the farming of Nile tilapia PL with recurrent outbreaks of bacterial diseases during the sex reversal phase.     

<Emphasis Type="Italic">Aloysia triphylla</Emphasis> in the zebrafish food: effects on physiology,behavior, and growth performance

Dietary supplements are commonly used by animals and humans and play key roles in diverse systems, such as the immune and reproductive systems, and in metabolism. Essential oils (EOs), which are natural substances, have potential for use in food supplementation; however, their effects on organisms remain to be elucidated. Here, we examine the effects of dietary Aloysia triphylla EO supplementation on zebrafish behavior, metabolism, stress response, and growth performance. We show that fish fed diets containing A. triphylla EO presented an anxiolytic response, with reduced exploratory activity and oxygen consumption; no changes were observed in neuroendocrine stress axis functioning and growth was not impaired. Taken together, these results suggest that the A. triphylla EO supplementation is a strong candidate for use in feed, since it ensures fish welfare (anxiolytic behavior) with decreased oxygen consumption. This makes it suitable for use in high-density production systems without causing damage to the neuroendocrine stress axis and without growth performance being impaired.     

Morpho‐demographic traits of two maërl‐forming algae in beds with different depths and fishing histories

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Effect of diet on growth and body biochemical composition of juvenile four‐sided sea cucumber Isostichopus badionotus (Selenka, 1867)

The farming of sea cucumber is a growing industry that demands feeds that are tailored to the organism's nutritional needs. Therefore, in this study, the effect of diet composition, with and without additives, on the growth, survival, specific growth rate (SGR) and body biochemical composition of the four‐sided sea cucumber Isostichopus badionotus was evaluated over a period of 3 months. Four diets were used: D1 (Macrocystis sp. and Sargassum sp.), D2 (Macrocystis sp. and Spirulina sp.), D3 (Sargassum sp. and Spirulina sp.) and D4 (Macrocystis sp., Sargassum sp. and Spirulina sp.), and the same diets enriched with 0.22% of Algamac 2000^® (D1H, D2H, D3H and D4H) were also tested. The organisms fed the diets containing Spirulina sp. demonstrated the highest growth rates and significantly greater SGR (% per day) (p < .05), an effect that was enhanced by the food additive (D2 0.67%; D2H 0.78%; D3H 0.76%). Survival and body composition were not affected by diet type. Based on these results, the use of Spirulina sp. combined with supplements rich in PUFA content is recommended in the formulation of diets to promote the growth of I. badionotus juvenile.     

Oxytetracycline depletion and withdrawal time estimation following intraperitoneal administration in three species from Chilean salmon farming

This study was conducted to evaluate the half‐time (T½) and withdrawal time (WT) of oxytetracycline (OTC) following intraperitoneal (i.p.) administration of OTC (24.8–34.7 mg/kg) in three farmed salmonid species, Coho salmon (Oncorhynchus kisutch), Rainbow trout (Oncorhynchus mikiss) and Atlantic salmon (Salmo salar). A detection technique in fish skin muscle through a high‐performance liquid chromatography (HPLC) with a diode array detector (DAD) was developed and validated. The depletion studies were carried out in controlled conditions (nine studies) and under field conditions (one study). The T½ and WT estimations from the skin muscle after the i.p. administration of OTC in salmonids appear to be longer than studies where the OTC was orally administrated. Furthermore, the OTC maximum concentration in muscle seems to be also higher in the i.p. treatment. Due to the prolonged WT following the i.p. OTC administration, cautions related to the salmon harvest time should be consider in order to prevent OTC traces in the final product.     

Sedative and antinociceptive effects of different combinations of detomidine and methadone in standing horses

Objective

To evaluate intravenous (IV) detomidine with methadone in horses to identify a combination which provides sedation and antinociception without adverse effects.

Initial recovery of compacted soil—planting and technical treatments decrease CO<Subscript>2</Subscript> concentrations in soil and promote root growth

Key message

The combination of technical treatments and planting of alder trees in a compacted forest soil improves the circulation of air and water through the pore system. This leads to decreases in CO ₂ concentrations and increases in root growth in the soil. Both are indicative of an initial recovery of soil structure.

Context

The compaction of forest soils, caused by forest machinery, has as a principal consequence: the destruction of soil structure and thus the reduction of the soil aeration status. Thus, the gas exchange between soil and atmosphere is reduced and the depth propagation of roots is limited, resulting in the shortage of water and nutrient supplies for trees.

Aims

This research aimed at detecting the first stages of recovery of soil structure in a compacted forest soil, which was treated with a combination of techniques (i.e., planting tree species, mulching, addition of lime), which could presumably accelerate the regeneration of soil structure.

Methods

The variation of CO₂ concentrations and the dynamics of root growth were repeatedly measured. Linear mixed models were developed in order to test the effects of the treatments and the planting of trees on soil aeration, as well as to identify the influence of the different environmental effects on CO₂ concentration in soil.

Results

The planting of root-active trees showed significant effects on decreases in CO₂ concentrations. However, during the short-term observation, some negative effects occurred especially for the mulched sites. Nevertheless, all applied technical treatments promoted an improved soil aeration and a higher root growth compared to untreated sites which points to an initial enhanced recovery of soil structure. Pronounced seasonal and interannual variations of soil respiration were highly influenced by soil temperature and soil water content variations.

Conclusion

An initial regeneration of soil structure is indicated by distinct changes of the soil aeration status. This regeneration is partially enhanced by the applied treatments. The quantitative potential of the regeneration techniques needs a longer observation period for mid- and long-term soil recoveries.