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Simple Summary: SCFAs are considered functional ingredients as they promote the growth and health of fish. This work aimed to assess the effect of short-chain fatty acids (SCFAs) on the immune status of the European sea bass gut through the ex vivo use of intestinal explants. The ex vivo technique significantly reduces the number of animals to be used, according to the guidelines of the 3Rs. The present results are important to understand how European sea bass respond to a bacterial infection after the administration of SCFAs and for the evaluation of functional ingredients used in aquaculture. This study aimed to evaluate the intestinal interactions between three short-chain fatty acids (SCFA), namely, acetate, propionate, and butyrate, and pathogenic bacteria (Vibrio anguillarum) in intestinal explants of European sea bass (Dicentrarchus labrax) juveniles. The anterior intestine of 12 fish with an average weight of 100 g (killed by excess anesthesia with 2-phenoxyethanol) were sampled and placed in 24-well plates. The experimental treatments consisted of a control medium and a control plus 1 mM or 10 mM of sodium acetate (SA), sodium butyrate (SB), and sodium propionate (SP). After 2 h of incubation, the explants were challenged with Vibrio anguillarum at 1 × 107 CFU/mL for 2 h. After the bacterial challenge, and regardless of the SCFA treatment, the oxidative stress-related genus catalase (cat) and superoxide dismutase (sod) were down-regulated and glutathione peroxidase (gpx) was up-regulated. Furthermore, the immune-related genes, i.e., the tumor necrosis factor (TNF-α), interleukin 8 (IL-8), transforming growth factor (TGF-β), and nuclear factor (NF-Kβ) were also up-regulated, and interleukin 10 (IL-10) was down-regulated. During the pre-challenge, sodium propionate and sodium butyrate seemed to bind the G-protein coupled receptor (grp40L), increasing its expression. During the challenge, citrate synthase (cs) was down-regulated, indicating that the SCFAs were used as an energy source to increase the immune and oxidative responses. Overall, our results suggest that sodium propionate and sodium butyrate may boost European sea bass immune response at the intestine level. [ABSTRACT FROM AUTHOR]

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Context. The knowledge of the genetic variability of gestation length and its correlations with other traits is relevant for selection decisions in beef cattle. Aims. Genetic parameters and trends were estimated for gestation length (first (GL1), repeated measures range of 1--6 (GL)) and traits currently used as selection criteria (birth weight (BW), weight gain from birth to weaning (BWG), weight gain from weaning to yearling (WYG), scrotal circumference (SC), score of conformation (YC), score of precocity (YP), and score of muscling (YM)) in Brazilian Angus cattle. In addition, direct and correlated selection responses were predicted. Methods. A series of single- and two-trait Bayesian analyses were performed on beef cattle data from14 farms across different regions of Brazil, by using linear and threshold animal models. Key results. A moderate heritability was estimated for GL1 (0.356 ± 0.058); however, the estimate for GL was low (0.189 ± 0.028) as was that for repeatability (0.204 ± 0.027). Lower accuracies of breeding values were obtained for GL than for GL1, ranging from0.490 ± 0.161 to 0.687 ± 0.037. Direct heritability estimates for growth and body composition traits were low, except for SC and BWG (0.301 ± 0.060 and 0.241 ± 0.019 respectively). Genetic correlations of 0.558 ± 0.121 and 0.739 ± 0.131 were estimated between GL1 and BW, and between GL and BW respectively. The other traits studied were estimated to have weak or nearzero genetic correlations with gestation length traits. Positive and moderate genetic associations were estimated between BW and BWG, SC, and visual scores (ranging from 0.338 ± 0.095 to 0.458 ± 0.092), but a near-zero estimate was obtained with WYG (0.127 ± 0.150). Weight gains were more highly genetically correlated with visual scores than between themselves (BWG and WYG) and with SC. The SC was highly genetically correlated with visual scores (0.684 ± 0.054 to 0.714 ± 0.050). Genetic trends showed that all traits studied have been changing in a positive direction, being unfavourable for BW and GL. Higher genetic gains were expected from using direct selection than from using indirect selection for GL1. Conclusions. Rapid growth is genetically associated with superior conformation, precocity and musculature, as well as a large scrotal circumference in males. However, selection decisions that heavily focus on these traits are likely to lead to more calving difficulties in the longer term. Implications. Selection indices should incorporate traits that measure calving difficulty directly if relevant records are available. Currently, considering its practical implications in primiparous anoestrus, the first-gestation length could serve as a viable alternative for inclusion in selection indices. Due to the low repeatability of the gestation length, decisions to cull on the basis of only one or two records of GL are highly inaccurate. [ABSTRACT FROM AUTHOR]