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The aim of this study was to evaluate the effect of two diets with different protein/fat ratios (P/F) (diet A: P/F 2.26; diet B: P/F 3.36) on the chemical composition, fatty acid profile and some somatic indexes of meagre (Argyrosomus regius). The trial was carried out on two groups of meagre raised in two different sea cages during 15 months. At the end of the production cycle biometric measures as well as chemical-nutritional analysis of the fillets were conducted on 25 fishes per group. Diet A, with a lower P/F, furnished animals with higher percentages of mesenteric fat (0.48 vs 0.41%; P<0.01) and of fillet yield (51.21 vs 48.12; P<0.01). Moreover, the fillets obtained with the diet A showed higher percentage of fat (3.60 vs 2.41%; P< 0.01), lower moisture (74.10 vs 75.42%; P<0.01), lower losses of water under pressure (16.73 vs 20.20%; P<0.01) and after 48 h of refrigeration (3.08 vs 4.23%; P<0.01). The fatty acids profile of fillets was affected by the diet. Diet A resulted in a higher level of saturated fatty acids (26.44 vs 23.17% of total lipid; P<0.01) and a lower percentage of polyunsaturated fatty acids (31.56 vs 36.08%; P<0.01) in the fillet, mainly due to the lower content of linoleic acid (13.63 vs 19.77%; P<0.01). The atherogenic (AI) and thrombogenic (TI) indexes, which resulted very low in the fish of Group B (AI=0.48 vs 0.60, P<0.01; TI=0.33 vs 0.37, P<0.01), together with the low lipid content of meat in both groups, confirmed the very high nutritional quality of meagre fillets.

Despite their role in host nutrition, the anaerobic gut fungal (AGF) component of the herbivorous gut microbiome remains poorly characterized. Here, to examine global patterns and determinants of AGF diversity, we generate and analyze an amplicon dataset from 661 fecal samples from 34 mammalian species, 9 families, and 6 continents. We identify 56 novel genera, greatly expanding AGF diversity beyond current estimates (31 genera and candidate genera). Community structure analysis indicates that host phylogenetic affiliation, not domestication status and biogeography, shapes the community rather than. Fungal-host associations are stronger and more specific in hindgut fermenters than in foregut fermenters. Transcriptomics-enabled phylogenomic and molecular clock analyses of 52 strains from 14 genera indicate that most genera with preferences for hindgut hosts evolved earlier (44-58 Mya) than those with preferences for foregut hosts (22-32 Mya). Our results greatly expand the documented scope of AGF diversity and provide an ecologically and evolutionary-grounded model to explain the observed patterns of AGF diversity in extant animal hosts.

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