Enhanced microwave absorption performance of Fe3Al flakes by optimizing the carbon nanotube coatings.

Fe3Al is a good magnetic loss absorber for microwave absorption. However, due to the relatively high density and poor impedance matching ratio, the potential of Fe3Al cannot be fully released. Herein, a dielectric loss absorber of carbon nanotubes (CNTs) is coupled with Fe3Al to form Fe3Al/CNTs composite absorbers. CNTs are randomly tangled and coated on the surface of the Fe3Al flakes, forming a connecting conductive network. By carefully tuning the content of CNTs, the optimized Fe3Al/CNTs composite absorber with 1.5% of CNTs can combine both magnetic loss and dielectric loss mechanisms, thus achieving an impedance matching ratio close to 1 while keeping strong attenuation for enhanced microwave absorption. As a result, an effective absorption bandwidth (RL ≤ -10 dB) of 4.73 GHz at a thickness of 2 mm is achieved.

Castration alters the ileum microbiota of Holstein bulls and promotes beef flavor compounds.

BACKGROUND: In the beef industry, bull calves are usually castrated to improve flavor and meat quality; however, this can reduce their growth and slaughter performance. The gut microbiota is known to exert a significant influence on growth and slaughter performance. However, there is a paucity of research investigating the impact of castration on gut microbiota composition and its subsequent effects on slaughter performance and meat flavor. RESULT: The objective of this study was to examine the processes via which castration hinders slaughter productivity and enhances meat quality. Bull and castrated calves were maintained under the same management conditions, and at slaughter, meat quality was assessed, and ileum and epithelial tissue samples were obtained. The research employed metagenomic sequencing and non-targeted metabolomics techniques to investigate the makeup of the microbiota and identify differential metabolites. The findings of this study revealed the Carcass weight and eye muscle area /carcass weight in the bull group were significantly higher than those in the steer group. There were no significant differences in the length, width, and crypt depth of the ileum villi between the two groups. A total of 53 flavor compounds were identified in the two groups of beef, of which 16 were significantly higher in the steer group than in the bull group, and 5 were significantly higher in the bull group than in the steer group. In addition, bacteria, Eukaryota, and virus species were significantly separated between the two groups. The lipid metabolism pathways of α-linolenic acid, linoleic acid, and unsaturated fatty acids were significantly enriched in the Steers group. Compared with the steer group, the organic system pathway is significantly enriched in the bull group. The study also found that five metabolites (LPC (0:0/20:3), LPC (20:3/0:0), LPE (0:0/22:5), LPE (22:5/0:0), D-Mannosamine), and three species (s_Cloning_vector_Hsp70_LexA-HP1, s_Bacteroides_Coprophilus_CAG: 333, and s_Clostridium_nexile-CAG: 348) interfere with each other and collectively have a positive impact on the flavor compounds of beef. CONCLUSIONS: These findings provide a basic understanding that under the same management conditions, castration does indeed reduce the slaughter performance of bulls and improve the flavor of beef. Microorganisms and metabolites contribute to these changes through interactions.

Effects of Oregano Essential Oil on IgA+, IgG+, and IgM+ Cells in the Jejunum of Castrated Holstein Bulls.

The aim of this study was to investigate the effect of oregano essential oil on IgA+, IgG+, and IgM+ cells in the jejunum of castrated Holstein bulls. Twelve castrated Holstein bulls were randomly divided into control (YCK) and oregano essential oil (YEO) groups. Pathological changes in the jejunum were observed by HE staining, and the expression levels of IgA, IgG, and IgM in the jejunum were detected by ELISA. The distributions of IgA+, IgG+, and IgM+ cells in the jejunum were analysed by multiplex immunofluorescence and immunohistochemistry. The results showed that the jejunal villi were detached in the YCK group, which may have been related to inflammation, while the intestinal epithelium was clear and intact in the YEO group. The expressions of IgA, IgG, and IgM were significantly reduced by 40.75%, 30.76%, and 50.87%. The IgA+, IgG+, and IgM+ cells were diffusely distributed in the lamina propria of the jejunum, and were reduced by 17.07%, 6.44%, and 6.15%, respectively. Oregano essential oil did not alter the distribution characteristics of IgA+, IgG+, or IgM+ cells in the jejunum, but it suppressed inflammatory response, decreased immunoglobulin content, and significantly enhanced the formation of an immune barrier in the gastrointestinal mucosa.

Oregano essential oil modulates colonic homeostasis and intestinal barrier function in fattening bulls.

Oregano essential oil (OEO) primarily contains phenolic compounds and can serve as a dietary supplement for fattening bulls. However, the precise molecular mechanism underlying this phenomenon remains largely elusive. Therefore, this study investigated the impact of adding OEO to diet on the integrity of the intestinal barrier, composition of the colonic microbiome, and production of microbial metabolites in fattening bulls. Our goal was to provide insights into the utilization of plant essential oil products in promoting gastrointestinal health and welfare in animals. We employed amplicon sequencing and metabolome sequencing techniques to investigate how dietary supplementation with OEO impacted the intestinal barrier function in bulls. The inclusion of OEO in the diet resulted in several notable effects on the colon of fattening bulls. These effects included an increase in the muscle thickness of the colon, goblet cell number, short-chain fatty acid concentrations, digestive enzyme activity, relative mRNA expression of intestinal barrier-related genes, and relative expression of the anti-inflammatory factor IL-10. Additionally, α-amylase activity and the relative mRNA expression of proinflammatory cytokines decreased. Moreover, dietary OEO supplementation increased the abundance of intestinal Bacteroides, Coprobacillus, Lachnospiraceae_UCG_001, and Faecalitalea. Metabolomic analysis indicated that OEO primarily increased the levels of 5-aminovaleric acid, 3-methoxysalicylic acid, and creatinine. In contrast, the levels of maltose, lactulose, lactose, and D-trehalose decreased. Correlation analysis showed that altered colonic microbes and metabolites affected intestinal barrier function. Taken together, these results demonstrate that OEO facilitates internal intestinal environmental homeostasis by promoting the growth of beneficial bacteria while inhibiting harmful ones.

Dietary oregano essential oil supplementation alters meat quality, oxidative stability, and fatty acid profiles of beef cattle.

This study was conducted to elucidate the effects of oregano essential oil (OEO) supplementation on the meat quality, antioxidant capacity, and nutritional value of the longissimus thoracis muscle in steers. Steers were divided into three groups (n = 9) and fed either a basal diet, or a basal diet supplemented with 130 mg/d OEO, or 230 mg/d OEO for 390 days. The results demonstrated that dietary OEO supplementation increased the total antioxidant capacity and activity of catalase, glutathione peroxidase, and superoxide dismutase, and decreased pH30min, pH24h, cooking loss, and malondialdehyde content. OEO increased the concentrations of polyunsaturated fatty acids and conjugated linoleic acid. In contrast, saturated fatty acids decreased, accompanied by increased essential amino acids, flavor amino acids, and total amino acids in the longissimus thoracis muscle. In summary, dietary OEO supplementation promotes the nutritional and meat quality of beef by maintaining its water-holding capacity and meat color, enhancing its antioxidative capacity, and preventing lipid oxidation.

Castration alters the cecal microbiota and inhibits growth in Holstein cattle.

To determine the effects of castration on growth performance, serum hormone levels, cecal microbiota composition, and metabolites in cattle. A total of 18 Holstein bulls and steers were divided into bull and steer groups and randomly assigned to 3 pens (3 cattle per pen, and each cattle were separated by a fence) to determine the average daily gain (ADG), daily dry matter intake (DMI), and feed efficiency (G/F). After the finishing trial, six cattle per group were randomly slaughtered. Serum was collected to measure the hormone concentration, and the cecal content was collected to measure the pH, short-chain fatty acids, and digestive enzyme activities. Metagenome sequencing and untargeted metabolomics were used to investigate the microbiota composition, functional profiles, and differential metabolites of the cecal contents. We found that castration significantly decreased ADG, DMI, and G/F in cattle (P < 0.05). The serum testosterone, thyroxine, growth hormone (P < 0.05), and triiodothyronine (P < 0.01) concentrations significantly decreased in the steer group when compared to those of the bull group. The activities of cellulase, xylanase, pectinase, and ß-glucosidase (P < 0.05) significantly decreased in the steer group, whereas the activities of lipase and α-amylase significantly increased. Moreover, castration significantly decreased the relative abundance of Ruminococcaceae_bacterium, Treponema_porcinum, Oscillibacter_sp. (P < 0.05), and Alistipes_senegalensis (P < 0.01), whereas the relative abundance of Phocaeicola_plebeius (P < 0.05) was significantly increased. Also, the relative abundance of Phocaeicola_plebeius was negatively correlated with testosterone levels, and the function of the cecal microbiota was enriched in the GH29 and GH97 families in the steer group. Metabolomic analysis indicated that castration increased the levels of L-valine, L-phenylalanine, L-aspartic acid, L-isoleucine, L-lysine, methionine, L-glutamic acid, and L-leucine, while decreasing the levels of α-ketoglutaric acid through the 2-oxocarboxylic acid metabolism pathway. In addition, α-ketoglutaric acid was negatively correlated with Oscillibacter_sp. (P < 0.01). Overall, castration can inhibit cattle growth by altering the composition of the cecal microbiota. Therefore, this study provides a theoretical and practical basis for improving the growth performance of steers.

The castration of male cattle is a routine management practice in the United States. It improves the quality grade and tenderness of beef, and steers have a more desirable meat quality than intact males. Thus, it is conducted to meet the human demand for quality meat. However, castration reduces the body and carcass weights of steers, resulting in increased feeding costs. Therefore, it is important to study the mechanisms of weight loss in steers to provide a theoretical basis for improving their growth in the future. Our results found that castration reduced the testosterone and growth hormone concentrations in serum, changed the cecal microbial composition and function, and decreased the relative abundance of Ruminococcaceae_bacterium and Oscillibacter_sp especially. These changes in the cecal microbiota decreased the activities of digestive enzymes that degrade cellulose and hemicellulose and decreased the levels of the metabolite α-ketoglutaric acid, thus, inhibiting steer growth. Therefore, the cecal microbiota may affect the growth performance of steers and provide a theoretical and practical basis for improving their growth.

[The effect of polymorphism F279Y of GHR gene on milk production trait in Chinese Holstein cattle].

OBJECTIVE: To study the effect of the polymorphism F279Y of the growth hormone receptor (GHR) gene on milk yield and composition in Chinese Holstein cattle. METHODS: Hundred thirty two Chinese Holstein cattle were selected as study materials, according to DHI production performance method to get the data of milk yield and composition; PCR- SSCP and sequencing method were used to detect the genotypes; least square method was used to acquire correlation analysis. RESULTS: Chinese Holstein cattle F279Y of GHR gene loci A and T allele frequency were 0.68 and 0.32, respectively, the experimental group significantly deviated from Hardy Weinberg equilibrium (P < 0.01); 305 d milk yield of AA genotype was significantly higher than AT type (P < 0.05), 305 d milk fat yield, 305 d milk protein yield and 305 d lactose of AT type had better trend than those of AA type in numeric; Therefore, allele A was dominant gene of high milk yield, allele T has positive effect on milk composition. CONCLUSION: Mutation F279Y of GHR gene can be used as genetic markers in Chinese Holstein milk production traits of marker assisted selection (MAS) breeding.