Palatability of animal oils included in the diet of the Mexican axolotl and its effect on growth and survival

Objective: The growth, survival and condition factor of Ambystoma mexicanum juveniles fed with three commercial feed-based diets coated with different animal oils as potential palatability enhancers were evaluated. Methodology: Three diets were prepared using commercial feed coated with fish, chicken and krill oil. The experiment lasted 81 days, the food was provided to the axolotls (6 per experimental unit, in triplicate) every 48 h, at 4% of the total biomass. The total weight of each experimental unit was recorded every 15 days, at the end of the experiment individual weight and height and survival were recorded. The following variables were calculated: Fulton's K, specific growth rate, coefficient of variation of final weight and size heterogeneity. Results: All three treatments showed an increase in total biomass, with a trend towards better performance in chicken and fish oil treatments compared to krill oil. When performing the statistical analysis, it was found that there were no significant differences among the treatments for any of the variables recorded. Implications: The three oils used in the present study were good palatable agents in the food intake of A. mexicanum. Conclusions: It is recommended to use chicken oil as an attractant additive in the formulation of a specific diet due to its low cost.Objective: The growth, survival, and condition factor of Ambystoma mexicanum juveniles fed with three commercial feed-based diets coated with different animal oils as potential palatability enhancers were evaluated. Methodology: Three diets were prepared using commercial feed coated with fish, chicken, and krill oil. The experiment lasted 81 days, the food was provided to the axolotls (6 per experimental unit, in triplicate) every 48 h, at 4% of the total biomass. The total weight of each experimental unit was recorded every 15 days, at the end of the experiment individual weight and height and survival were recorded. The following variables were calculated: Fulton's K, specific growth rate, coefficient of variation of final weight and size heterogeneity. Results: All three treatments showed an increase in total biomass, with a trend towards better performance in chicken and fish oil treatments compared to krill oil. When performing the statistical analysis, it was found that there were no significant differences among the treatments for any of the variables recorded. Implications: The three oils used in the present study were good palatable agents in the food intake of A. mexicanum. Conclusions: It is recommended to use chicken oil as an attractant additive in the formulation of a specific diet due to its low cost

Biology and use of the Pacific fat sleeper Dormitator latifrons (Richardson, 1844): state of the art review

The present work is a review of the literature on the native Mexican fish Dormitator latifrons. The aim is to contribute to the integration and systematization of current knowledge to make it easier to identify existing knowledge gaps and breakthroghs Moreover, promote the successful cultivation and protection of this species whose consumption is increasing in Latin America. A review of the articles related to D. latifrons published in international and regional databases was carried out. The articles reviewed focus on taxonomy and systematics, phylogenetic, geographic distribution, ecology, physiology, reproduction, development, pathology, health, and the technologies used to cultivate this fish species. The conclusion is that, even though the cultivation of D. latifrons is of commercial interest in some countries, there are still significant gaps in our knowledge of biology and, consequently, the domestication potential of the species. Filling these gaps will require systematic research efforts on protecting natural populations and improving mass cultivation techniques.Fil: Vega Villasante, Fernando. Universidad de Guadalajara; MéxicoFil: Ruiz González, Luis E.. Universidad de Guadalajara; MéxicoFil: Chong Carrillo, Olimpia. Universidad de Guadalajara; MéxicoFil: Basto Rosales, Mao E. R.. Tecnológico Nacional de Bahía de Banderas; MéxicoFil: Palma Cancino, David J.. Universidad de Guadalajara; MéxicoFil: Tintos Gómez, Adrián. Universidad Tecnológica de Manzanillo; MéxicoFil: Montoya Martínez, Cynthia E.. Universidad de Guadalajara; MéxicoFil: Kelly Gutiérrez, Liza D.. Universidad de Guadalajara; MéxicoFil: Guerrero Galván, Saúl R.. Universidad de Guadalajara; MéxicoFil: Ponce Palafox, Jesús T.. Universidad Autónoma de Nayarit; MéxicoFil: Zapata, Ana. Universidad de Guadalajara; MéxicoFil: Musin, Gabriela Eliana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; ArgentinaFil: Badillo Zapata, Daniel. Universidad de Guadalajara; Méxic

Somatic indices and nutritional composition of the roe of the native fish Dormitator latifrons: no aplica

Objective: To evaluate some reproductive aspects of D. latifrons and the nutritional quality of its eggs. Design/methods/approach: Eighty-two fish were randomly collected (August 2021), and their sex, length, weight, somatic indices, Fulton condition index (K), proximate composition, and amino acid and lipid composition (fatty acids) of the gonads were determined. Results: Of the total specimens collected, 62% were females; length and weight values were higher in males, but their gonadosomatic index (GSI) was lower than in females. Somatic indices did not show differences between different weight ranges. In the roe of D. latifrons, the average proximate composition was 24.3% protein and 8.5% lipids. The most abundant essential amino acids were leucine and lysine. Linoleic acid (C18:2n6) was the fatty acid with the highest concentration. Limitations/implications: It is necessary to complement the analysis of the amino acid and fatty acid profile of the roe in wild organisms to relate the changes caused by balanced feed. Findings/conclusions: This study shows that the D. latifrons roe is a good source of amino acids and PUFA. Keywords: proximate composition, fatty acids, essential amino acidsObjective: To evaluate some reproductive aspects of D. latifrons and the nutritional quality of its eggs. Design/methods/approach: Eighty-two fish were randomly collected (August 2021), and their sex, length, weight, somatic indices, Fulton condition index (K), proximate composition, and amino acid and lipid composition (fatty acids) of the gonads were determined. Results: Of the total specimens collected, 62% were females; length and weight values were higher in males, but their gonadosomatic index (GSI) was lower than in females. Somatic indices did not show differences between different weight ranges. In the roe of D. latifrons, the average proximate composition was 24.3% protein and 8.5% lipids. The most abundant essential amino acids were leucine and lysine. Linoleic acid (C18:2n6) was the fatty acid with the highest concentration. Limitations/implications: It is necessary to complement the analysis of the amino acid and fatty acid profile of the roe in wild organisms to relate the changes caused by balanced feed. Findings/conclusions: This study shows that the D. latifrons roe is a good source of amino acids and PUFA

New findings in the searching of an optimal diet for the axolotl Ambystoma mexicanum: protein levels

Objective: To determine the protein nutritional requirements in juvenile axolotls, for this purpose, four isocaloric diets (8 % lipids) with 30, 35, 30 and 45 % protein were prepared. Design / methodology / approach: Six axolotls were used per test, during a period of 81 days. The diets were prepared using fishmeal as a protein source and fish oil as a lipid source. The feed was supplied every 48 hours with 4% of the weight of the biomass of organisms per experimental reservoir. Four biometries were performed throughout the experiment and growth parameters were determined: height, weight gained per day, specific growth rate, survival, Fulton's K, and protein efficiency rate. The digestibility of each of the diets was also determined. Results: There were significant differences (p> 0.05) in the growth and survival of the axolotls, the diet with 45% protein showed the best growth results. Limitations / Implications: No more protein levels could be tested, due to the number of organisms available for bioassays. Findings / conclusions: Diets for A. mexicanum containing 45% protein level promote good development and survival. This allows for improved cultivation and management plans for the species.Objective: To determine the protein nutritional requirements in juvenile axolotls, for this purpose, four isocaloric diets (8 % lipids) with 30, 35, 30 and 45 % protein were prepared. Design / methodology / approach: Six axolotls were used per test, during a period of 81 days. The diets were prepared using fishmeal as a protein source and fish oil as a lipid source. The feed was supplied every 48 hours with 4% of the weight of the biomass of organisms per experimental reservoir. Four biometries were performed throughout the experiment and growth parameters were determined: height, weight gained per day, specific growth rate, survival, Fulton's K, and protein efficiency rate. The digestibility of each of the diets was also determined. Results: There were significant differences (p> 0.05) in the growth and survival of the axolotls, the diet with 45% protein showed the best growth results. Limitations / Implications: No more protein levels could be tested, due to the number of organisms available for bioassays. Findings / conclusions: Diets for A. mexicanum containing 45% protein level promote good development and survival. This allows for improved cultivation and management plans for the species

First attempt to fill gaps in the feeding of the axolotl: Atractability of animal oils for Ambystoma mexicanum

Objective: To determinate the attractability of four oils, fish, chicken, krill and red crab (Pleuroncodes planipes) for Ambystoma mexicanum juveniles, evaluating their feeding behavior using a Y aquarium.Design/Methodology/Approach: Ten axolotls were used per test, fasted for 48 hours. Gels with oils were prepared using gelatin and poured into petri dishes and refrigerated until gelation. A recording of the test was made using two video cameras. In the feed chamber the gelled oil was placed and allowed to stand for 15 minutes. On the other chamber a gelled disk with no other ingredient than gelatin and water was placed. The video recording began once the 15 minutes of gel permanence had finished, removing the barrier so that the axolotls could move through the rest of the aquarium.  All tests were carried out with a recording time of 30 min.Results: Fish oil demonstrated a lower attraction effect compared to krill, red crab and chicken oils (P <0.05), while chicken oil (30.00 ± 1.73) doubled the attractive effect of krill oil (16.00 ± 1.00).Limitations of the study/implications: It was necessary to condition a room with controlled environmental temperature for A. mexicanum (18 ± 1 °C).Findings/Conclusions: Krill and chicken oil are good feeding effectors for A. mexicanum causing positive feeding behavior. The use of chicken oil is desirable because of its low cost compared to krill.Objective: To determinate the attractability of four oils, fish, chicken, krill, and red crab (Pleuroncodes planipes) for Ambystoma mexicanum juveniles, evaluating their feeding behavior using a Y aquarium.Design/Methodology/Approach: Ten axolotls were used per test, fasted for 48 h. Gels with oils were prepared using gelatin and poured into petri dishes and refrigerated until gelation. A recording of the test was made using two video cameras. In the feed chamber the gelled oil was placed and allowed to stand for 15 min. On the other chamber a gelled disk with no other ingredient than gelatin and water was placed. The video recording began once the 15 min of gel permanence had finished, removing the barrier so that the axolotls could move through the rest of the aquarium.  All tests were carried out with a recording time of 30 min.Results: Fish oil demonstrated a lower attraction effect compared to krill, red crab and chicken oils (P <0.05), while chicken oil (30.00 ± 1.73) doubled the attractive effect of krill oil (16.00 ± 1.00).Limitations of the study/implications: It was necessary to condition a room with controlled environmental temperature for A. mexicanum (18 ± 1 °C).Findings/Conclusions: Krill and chicken oil are good feeding effectors for A. mexicanum causing positive feeding behavior. The use of chicken oil is desirable because of its low cost compared to krill

Risk of COVID-19 after natural infection or vaccinationResearch in context

Background: While vaccines have established utility against COVID-19, phase 3 efficacy studies have generally not comprehensively evaluated protection provided by previous infection or hybrid immunity (previous infection plus vaccination). Individual patient data from US government-supported harmonized vaccine trials provide an unprecedented sample population to address this issue. We characterized the protective efficacy of previous SARS-CoV-2 infection and hybrid immunity against COVID-19 early in the pandemic over three-to six-month follow-up and compared with vaccine-associated protection. Methods: In this post-hoc cross-protocol analysis of the Moderna, AstraZeneca, Janssen, and Novavax COVID-19 vaccine clinical trials, we allocated participants into four groups based on previous-infection status at enrolment and treatment: no previous infection/placebo; previous infection/placebo; no previous infection/vaccine; and previous infection/vaccine. The main outcome was RT-PCR-confirmed COVID-19 >7–15 days (per original protocols) after final study injection. We calculated crude and adjusted efficacy measures. Findings: Previous infection/placebo participants had a 92% decreased risk of future COVID-19 compared to no previous infection/placebo participants (overall hazard ratio [HR] ratio: 0.08; 95% CI: 0.05–0.13). Among single-dose Janssen participants, hybrid immunity conferred greater protection than vaccine alone (HR: 0.03; 95% CI: 0.01–0.10). Too few infections were observed to draw statistical inferences comparing hybrid immunity to vaccine alone for other trials. Vaccination, previous infection, and hybrid immunity all provided near-complete protection against severe disease. Interpretation: Previous infection, any hybrid immunity, and two-dose vaccination all provided substantial protection against symptomatic and severe COVID-19 through the early Delta period. Thus, as a surrogate for natural infection, vaccination remains the safest approach to protection. Funding: National Institutes of Health

Risk of COVID-19 after natural infection or vaccinationResearch in context

Summary: Background: While vaccines have established utility against COVID-19, phase 3 efficacy studies have generally not comprehensively evaluated protection provided by previous infection or hybrid immunity (previous infection plus vaccination). Individual patient data from US government-supported harmonized vaccine trials provide an unprecedented sample population to address this issue. We characterized the protective efficacy of previous SARS-CoV-2 infection and hybrid immunity against COVID-19 early in the pandemic over three-to six-month follow-up and compared with vaccine-associated protection. Methods: In this post-hoc cross-protocol analysis of the Moderna, AstraZeneca, Janssen, and Novavax COVID-19 vaccine clinical trials, we allocated participants into four groups based on previous-infection status at enrolment and treatment: no previous infection/placebo; previous infection/placebo; no previous infection/vaccine; and previous infection/vaccine. The main outcome was RT-PCR-confirmed COVID-19 >7–15 days (per original protocols) after final study injection. We calculated crude and adjusted efficacy measures. Findings: Previous infection/placebo participants had a 92% decreased risk of future COVID-19 compared to no previous infection/placebo participants (overall hazard ratio [HR] ratio: 0.08; 95% CI: 0.05–0.13). Among single-dose Janssen participants, hybrid immunity conferred greater protection than vaccine alone (HR: 0.03; 95% CI: 0.01–0.10). Too few infections were observed to draw statistical inferences comparing hybrid immunity to vaccine alone for other trials. Vaccination, previous infection, and hybrid immunity all provided near-complete protection against severe disease. Interpretation: Previous infection, any hybrid immunity, and two-dose vaccination all provided substantial protection against symptomatic and severe COVID-19 through the early Delta period. Thus, as a surrogate for natural infection, vaccination remains the safest approach to protection. Funding: National Institutes of Health

Inclusive J/ψ production in pp collisions at √s=2.76 TeV

The ALICE Collaboration has measured inclusive J/ψ production in pp collisions at a center-of-mass energy √s=2.76 TeV at the LHC. The results presented in this Letter refer to the rapidity ranges |y|<0.9 and 2.5<y<4 and have been obtained by measuring the electron and muon pair decay channels, respectively. The integrated luminosities for the two channels are Linte=1.1 nb−1 and Lintμ=19.9 nb−1, and the corresponding signal statistics are NJ/ψe+e−=59±14 and NJ/ψμ+μ−=1364±53. We present dσJ/ψ/dy for the two rapidity regions under study and, for the forward-y range, d2σJ/ψ/dydpt in the transverse momentum domain 0<pt<8 GeV/c. The results are compared with previously published results at s=7 TeV and with theoretical calculations

Neutral pion and η meson production in proton–proton collisions at √s=0.9 TeV and s=√7 TeV

he first measurements of the invariant differential cross sections of inclusive π0 and η meson production at mid-rapidity in proton–proton collisions at s=0.9 TeV and s=7 TeV are reported. The π0 measurement covers the ranges 0.4<pT<7 GeV/c and 0.3<pT<25 GeV/c for these two energies, respectively. The production of η mesons was measured at s=√7 TeV in the range 0.4<pT<15 GeV/c. Next-to-Leading Order perturbative QCD calculations, which are consistent with the π0 spectrum at s=0.9 TeV, overestimate those of π0 and η mesons at s=√7 TeV, but agree with the measured η/π0 ratio at s=√7 TeV

Light vector meson production in pp collisions at √s=7 TeV

The ALICE experiment has measured low-mass dimuon production in pp collisions at √s=7 TeV in the dimuon rapidity region 2.5<y<4. The observed dimuon mass spectrum is described as a superposition of resonance decays (η,ρ,ω,η′,ϕ) into muons and semi-leptonic decays of charmed mesons. The measured production cross sections for ω and ϕ are σω(1<pt<5 GeV/c,2.5<y<4)=5.28±0.54(stat)±0.49(syst) mb and σϕ(1<pt<5 GeV/c,2.5<y<4)=0.940±0.084(stat)±0.076(syst) mb. The differential cross sections d2σ/dydpt are extracted as a function of pt for ω and ϕ. The ratio between the ρ and ω cross section is obtained. Results for the ϕ are compared with other measurements at the same energy and with predictions by models