Germán Olivares-Cantillano

Hops (Humulus lupulus L.) are a phytochemical resource rich in bitter acids, prenylated flavonoids, and essential oils with antimicrobial, antifungal, antioxidant, and anti-inflammatory activities relevant to animal production. This review critically synthesizes the phytochemical profile of H. lupulus and the available in vivo evidence on its use as a functional feed additive in poultry, freshwater aquaculture, swine, and ruminants, identifying research gaps and regulatory barriers. In poultry, microencapsulated β-acids at 30 mg/kg feed achieved a feed conversion ratio comparable to zinc bacitracin, while lupulone reduced intestinal Clostridium perfringens counts by >4 log units, from log₁₀ 6.20 to 2.00 CFU/g; doses ≥240 mg/kg induced adverse effects. In freshwater aquaculture, hop extract at 750 mg/kg feed improved hepatic markers and fillet fatty acid composition in common carp, whereas isolated hop acids at 308 mg/kg increased final body weight in Nile tilapia (157.3 vs. 150.3 g) without sensory rejection even at 1230 mg/kg. In swine, granulated cones improved feed conversion (3.5 vs. 4.3 kg/kg), while purified β-acids up to 360 mg/kg improved performance comparably to colistin. In ruminants, hop residues, pellets, and cones were tolerated without consistent production benefits. Overall, hop-derived additives show dose-, compound-, and matrix-dependent effects, requiring standardized formulations, species-specific pharmacokinetics, pathogen-challenge validation, long-term safety assessment, and regulatory dossiers.

Water quality and the culture performance of juvenile rainbow trout (Oncorhynchus mykiss) were evaluated between 2014 and 2017 in a recirculating aquaculture system (RAS) in the Chilean Altiplano. Key parameters such as temperature, total ammonia nitrogen (TAN), nitrates, and dissolved oxygen were monitored, with values ranging from 7 to 21 °C, <0.1 to 0.63 mg/L, 2.0 to 135 mg/L, and 1.8 to 7.5 mg/L, respectively. Additional parameters—including alkalinity, arsenic, chlorine, true color, conductivity, hardness, phosphorus, pH, potassium, suspended solids, and salinity—were also assessed, comparing different points within the system (head tank, culture tanks, and settling tanks). The results showed that water quality remained within acceptable ranges for aquaculture, although fluctuations in pH and low alkalinity levels caused stress in the fish. Despite these challenges, the specific growth rate (SGR) was 1.49, the feed conversion ratio (FCR) was 1.52, and weight gain reached 298.7%, with a survival rate of 96.2%. This study demonstrates that aquaculture in the Altiplano is feasible and can contribute to the sustainable development of aquaculture in the region. Furthermore, it highlights the importance of comprehensive water quality monitoring to optimize RAS performance in challenging environments.

This study monitored the conditioning of rainbow trout (Oncorhynchus mykiss) broodstock in a closed culture system at 3000 m above sea level (m.a.s.l.) to evaluate the feasibility of this culture method and assess the first spawning of the species under these conditions as an alternative production route for the communities present in the foothills of Cordillera de los Andes, northern Chile. A total of 120 specimens with an initial weight of 170 g were used. They were maintained in a recirculation aquaculture system (RAS) composed of protected circular tanks, decanters, a biofilter, and oxygenation equipment. Fish growth was monitored through parameters such as specific growth rate (SGR), feed conversion ratio (FCR) and percent weight growth (PWG), parameters that were maintained within those reported by other authors for this species. The first successful spawning occurred after 12 months of broodstock conditioning, yielding 8570 eggs, of which 6569 hatched successfully. The success of this conditioning and spawning not only broadens the understanding of adaptability to high-altitude environments, but also provides evidence for the potential diversification of productive activities in foothill areas through aquaculture.

Given the overexploitation of fisheries and the growing consumption of sea products, aquaculture is emerging as an alternative to meet the demand for protein at regional, national, and global levels. In northern Chile, the foothills of the Andes offer an opportunity for sustainable economic diversification. In this study, results of a rainbow trout (Oncorhynchus mykiss) culture in a recirculation system are presented, analyzing its growth and performance under altitude conditions. The research was carried out in Copaquilla, a small area in the foothills of northern Chile, 3000 m above sea level. Five thousand 15 g juvenile trout were acquired and transported by land from the Rio Blanco fish farm, successfully traveling more than 2100 km. During the 20-month-long culture, several growth parameters were evaluated, including specific growth rate, percentage of weight growth, feed conversion factor, survival, and Fulton’s condition factor. All these parameters were within the normal growth range for trout, evidencing good-quality growth of the organisms. The results offer evidence that rainbow trout farming at 3000 m above sea level is viable and presents a viable performance, opening new opportunities for aquaculture in northern Chile.