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Analysis of model systems, for example in mice, has shown that the microbiota in the gastrointestinal tract can play an important role in the efficiency of energy extraction from diets. The study reported here aimed to determine whether there are correlations between gastrointestinal tract microbiota population structure and energy use in chickens. Efficiency in converting food into muscle mass has a significant impact on the intensive animal production industries, where feed represents the major portion of production costs. Despite extensive breeding and selection efforts, there are still large differences in the growth performance of animals fed identical diets and reared under the same conditions. Variability in growth performance presents management difficulties and causes economic loss. An understanding of possible microbiota drivers of these differences has potentially important benefits for industry. In this study, differences in cecal and jejunal microbiota between broiler chickens with extreme feed conversion capabilities were analysed in order to identify candidate bacteria that may influence growth performance. The jejunal microbiota was largely dominated by lactobacilli (over 99% of jejunal sequences) and showed no difference between the birds with high and low feed conversion ratios. The cecal microbial community displayed higher diversity, and 24 unclassified bacterial species were found to be significantly (<0.05) differentially abundant between high and low performing birds. Such differentially abundant bacteria represent target populations that could potentially be modified with prebiotics and probiotics in order to improve animal growth performance.[PUBLICATION ABSTRACT]

Major feed ingredients, like maize and soya, and land resources are used by both humans and animals, causing competition and affecting costs. To make the poultry industry profitable, it is important to prevent wastage of feed, and feed efficiency is therefore important. Residual feed intake (RFI) and feed conversion ratio (FCR) are two measures of feed efficiency used to assess production efficiency. This review describes a different aspect of feed efficiency measures and how their correlated traits affect poultry production. Bird selection, based on RFI and FCR at the 5th week or market age, is effective since both are low to moderately heritable (heritability estimates of RFI and FCR are 0.21-0.49 and 0.11-0.44 respectively). Both RFI and FCR selection results in reduced feed intake without compromising growth rate. Selection based on RFI is better in comparison to FCR for improving feed efficiency, as it is a trait independent of the maintenance energy requirement of an individual bird. Bird with low RFI value can be expected to have better feed efficiency and can be helpful in lowering the cost of poultry production.

The aim of this study was to evaluate the effects of agro-industrial byproduct-based diets on the productive parameters, digestibility, insect composition, and gut microbiota of mealworm (Tenebrio molitor) larvae. Three formulations corresponding to three different levels of starch and protein were tested: one formulation based on bread remains and brewer’s yeast, representing a diet of high starch (61.1%) and low crude protein (18.5%) (HS-LP); and two formulations in which an additional four byproducts (courgette (Cucurbita pepo) remains, tigernut (Cyperus scelentus) pulp, brewer’s spent grains, and rice straw) were incorporated in different proportions, consistent with a diet of both moderate starch (29.8%) and crude protein (21.0%) (MS-MP); and another corresponding to a diet of low starch (20.0%) and high crude protein (26.3%) (LS-HP). A total of 1920 young larvae (average weight = 0.65 mg per larva) were used in this study. The larvae were randomly distributed into 16 replicates per treatment (boxes of 22.5 cm × 14.0 cm × 4.75 cm). Ten replicates for the growth performance–digestibility trial and six replicates for the complementary trial to determine uric acid levels in the frass were assigned per treatment. For growth performance, the diets were administered ad libitum during the experiment. The average number of days for the larvae to start pupating was lower in those reared on the HS-LP and LS-HP diets (88.90 and 91.00 days, respectively) than those on the MS-MP diet (120.09 days) (p < 0.001). The final individual weight was higher (p < 0.001) in larvae of the LS-HP group (168.69 mg) compared to those of the other groups (100.29 and 112.99 mg for HS-LP and MS-MP, respectively). However, the feed conversion ratio was better (p < 0.001) in the HS-LP group with the lowest value (1.39 g/g), with dry matter digestibility being the highest for the same diet (70.38%) (p < 0.001). Mealworms reared on LS-HP and MS-MP diets had a higher crude protein content than those reared on the HS-LP diet (p = 0.039). The most abundant phyla in the gut microbiota of larvae were Tenericutes, Proteobacteria, and Firmicutes, with their abundance depending on the rearing substrate. The representation of Tenericutes phylum was higher (p < 0.05) in the mealworms reared on MS-MP and HS-LP diets, whereas Proteobacteria and Cyanobacteria were higher in abundance (p < 0.001) in the insects reared on LS-HP. In conclusion, the larval growth, digestibility, insect composition, and gut microbiota of Tenebrio molitor were found to depend on the composition of the administered diet, and the results suggest great potential for the use of agro-industrial byproducts in their rearing and production.

In this paper, a broadband polarization conversion metasurface in microwave regime based on cross-shaped resonators was proposed. The simulated results show that the converter can convert linear polarization wave into its cross-polarization wave, 2 dB bandwidth is 11.5–21.8 GHz, and the Polarization Conversion Ratio is greater than 96% in this range. The simulated surface current distributions show that there are three plasmon resonances generated by magnetic resonances and electric resonance, resulting in broadband cross-polarized reflections, and electromagnetic composite resonances in the same direction will inhibit cross-polarization reflection. The proposed converter presents polarization selectivity, which can only convert the y - and x -polarized waves completely. When the incident angles reach 40°, the converter also shows high-efficiency polarization conversion. The experimental results are highly consistent with the simulation ones. This work may have some potential application in polarization-controlled devices, stealth surfaces, antennas and etc.

This paper introduces a perfect metamaterial absorber (MMA) achieving exceptional electromagnetic signal absorption at application-oriented frequencies of 2.40 and 3.50 GHz in addition to 6.09 GHz. The MMA exhibits absorption rates of 99.85, 98.6, and 96.7%, with high shielding effectiveness (SE) of 36.44, 32.58, and 31.13 dB against electromagnetic interference (EMI) at those frequencies. The structure of the copper resonator on the FR4 substrate allows the on-design frequency switching from 3.43 to 3.70 and 5.65 to 6.55 GHz, respectively. The structural symmetry enables polarization and incidence angle independence up to 60° for both transverse electric and magnetic modes. The perfect absorption of the MMA is shown by the near-zero polarization conversion ratio. There is an adjacent correlation between the measurement and simulation results. The proposed MMA emerges as an efficient EMI shield for Wi-Fi and 5G signals, offering perfect absorption and extensive polarization characteristics.

Biofloc-based systems provide a sustainable strategy for nitrogen management in intensive aquaculture, but their efficiency depends strongly on carbon availability and microbial community regulation. In this study, we evaluated the combined effects of carbon-to-nitrogen (C: N) ratio regulation and Candida utilis supplementation on nitrogen removal and microbial community dynamics in a biofloc-based Chinese soft-shelled turtle culture system. Three C: N ratios (10, 15, and 20) were established using glucose as the carbon source, with or without C. utilis addition. Water quality parameters, feed conversion ratio (FCR), bacterial community composition (16 S rRNA sequencing), and antagonistic activity against Aeromonas hydrophila were analyzed. Increasing the C: N ratio significantly enhanced ammonia nitrogen removal through stimulated heterotrophic assimilation. Supplementation with C. utilis further reduced inorganic nitrogen concentrations across all C: N conditions and improved feed utilization efficiency. Microbial community analyses showed increased bacterial richness and diversity, accompanied by significant shifts in community composition. Notably, opportunistic pathogens such as Aeromonas were markedly suppressed in yeast-supplemented treatments. Co-culture experiments further demonstrated that live C. utilis inhibited A. hydrophila , suggesting a metabolism-dependent antagonistic mechanism. These findings indicate that integrating C: N regulation with C. utilis supplementation can enhance nitrogen transformation efficiency and microbial stability in biofloc systems, providing a promising strategy for sustainable aquaculture management.

An efficient broadband metasurface-based polarization converter is investigated in this communication. The proposed embodiment works in the reflection mode. It can efficiently convert the x -polarized fields to their y -polarized counterpart and vice versa, with a good oblique incidence of up to 50° over the entire X-band. The design portrays a good polarization conversion ratio of up to 98% for normal incidence and is more than 70% considering the cases of oblique incidences. A prototype is fabricated to confirm the operation of the proposed design. Good agreement between the simulation and experimental results is observed. R yy (co-component: y -polarized transmission and y -polarized reception) is below -10 dB, and the R xy (cross-component: y -polarized transmission and x -polarized reception) is above – 3 dB over the entire X-band.

The goal of this study was to evaluate the microbial communities in the gut and feces from female finishing Landrace pigs with high and low feed conversion ratio (FCR) by 16S rRNA gene amplicon sequencing. Many potential biomarkers can distinguish between high and low FCR groups in the duodenum, ileum, cecum, colon, and rectum, according to linear discriminant analysis effect sizes. The relative abundance of microbes were tested by Mann–Whitney test between the high and low FCR groups in different organs: Campylobacter, Prevotella and Sphaerochaeta were different in the duodenum (P < 0.05); Sanguibacter, Kingella and Anaeroplasma in jejunum; Anaeroplasma, Arthrobacter, Kingella, Megasphaera and SMB53 in the ileum; Butyricicoccus, Campylobacter, Mitsuokella, and Coprobacillus in the cecum; Lactococcus and Peptococcus in the colon; Staphylococcus in the rectum; and Rothia in feces. The prevalence of microbial genera in certain locations could potentially be used as biomarkers to distinguish between high and low FCR. Functional prediction clustering analysis suggested that bacteria in the hindgut mainly participated in carbohydrate metabolism and amino acid metabolism, and different in the relative abundance of metabolic pathways, as predicted from the microbial taxa present, were identified by comparing the high and low groups of each location. The results may provide insights for the alteration of the intestinal microbial communities to improve the growth rate of pigs.

Insects have been proposed as potential alternative animal protein sources to replace fishmeal (FM), which is expensive and has limited availability for fish feed formulation. However, studies on the effects of replacing FM with black soldier fly (Hermetia illucens) larvae (BSF‐L) on growth performance of Nile tilapia (Oreochromis niloticus) fry, water quality and economic benefits are currently limited. This study determined the effects of replacing 100% FM, 75% FM, 50% FM, 25% FM and 0% FM with cheap BSF‐L meal, hereafter referred to as BSF‐L0, BSF‐L25, BSF‐L50, BSF‐L75 and BSF‐L100 diets, respectively for rearing all‐male Nile tilapia fry produced by YY technology. The study further determined the optimum percentage of BSF‐L meal for maximum growth of Nile tilapia fry. A total of 2400 visually healthy Nile tilapia fry weighing 0.001 g were randomly stocked into 20 plastic tanks (120 fry per tank, four replicates per treatment) and fed the BSF‐L diets for 12 weeks. The BSF‐L75 diet increased significantly specific growth rate, total weight gain, Zihler's index of fry and nitrate in the culture water but reduced feed conversion ratio of diet and total suspended solids in the culture water (p < 0.05). Feeding the Nile tilapia fry with BSF‐L50 diet increased significantly hepatosomatic index (p < 0.05). The diets with BSF‐L75 and BSF‐L100 reduced significantly the incidence cost by 31.97% and 28.77% (p < 0.05), and increased profit index by 3.97 and 3.44%, respectively. The optimum percentage of BSF‐L inclusion required for maximum growth performance of Nile tilapia fry was estimated as 81% to 84% based on polynomial analysis. Taken together, feeding Nile tilapia fry with diets containing 81% to 84% BSF‐L meal improved growth performance. The BSF‐L75 diet enhanced feed efficiency and had no deleterious effect on the liver and intestines. Meanwhile, it improved nitrate concentration for increased natural productivity. Incorporating 75% BSF‐L meal in diets for Nile tilapia fry reduced 30% of feed cost leading to 4% higher economic returns. Fishmeal is expensive and has limited availability for fish feed formulation. In this study we show that, the expensive and limited availability fishmeal can be replaced by diets containing 81% to 84% black soldier fry meal for improved growth performance and feed efficiency in Nile tilapia fry. Incorporating 75% BSF‐L meal in diets for Nile tilapia fry reduced 30% of feed cost leading to 4% higher economic returns.

Background The feed conversion ratio (FCR) is an important productive trait that greatly affects profits in the pig industry. Elucidating the genetic mechanisms underpinning FCR may promote more efficient improvement of FCR through artificial selection. In this study, we integrated a genome-wide association study (GWAS) with transcriptome analyses of different tissues in Yorkshire pigs (YY) with the aim of identifying key genes and signalling pathways associated with FCR. Results A total of 61 significant single nucleotide polymorphisms (SNPs) were detected by GWAS in YY. All of these SNPs were located on porcine chromosome (SSC) 5, and the covered region was considered a quantitative trait locus (QTL) region for FCR. Some genes distributed around these significant SNPs were considered as candidates for regulating FCR, including TPH2 , FAR2 , IRAK3 , YARS2 , GRIP1 , FRS2 , CNOT2 and TRHDE . According to transcriptome analyses in the hypothalamus, TPH2 exhibits the potential to regulate intestinal motility through serotonergic synapse and oxytocin signalling pathways. In addition, GRIP1 may be involved in glutamatergic and GABAergic signalling pathways, which regulate FCR by affecting appetite in pigs. Moreover, GRIP1 , FRS2 , CNOT2 , and TRHDE may regulate metabolism in various tissues through a thyroid hormone signalling pathway. Conclusions Based on the results from GWAS and transcriptome analyses, the TPH2 , GRIP1 , FRS2 , TRHDE , and CNOT2 genes were considered candidate genes for regulating FCR in Yorkshire pigs. These findings improve the understanding of the genetic mechanisms of FCR and may help optimize the design of breeding schemes.