Dietary Beta-Hydroxy-Beta-Methyl Butyrate Supplementation Inhibits Hepatic Fat Deposition via Regulating Gut Microbiota in Broiler Chickens

The present study is aimed to explore the effects of different dietary beta-hydroxy-beta-methyl butyrate (HMB) levels (0, 0.05%, 0.10%, or 0.15%) on liver lipid metabolism on Wenshi broiler chickens. Results showed that HMB reduced the liver weight as well as liver concentrations of triacylglycerol (TG) and total cholesterol (TC) (quadratically, p < 0.05), and the lowest values were observed in the 0.10% HMB group. Meanwhile, HMB supplementation significantly altered the expression levels of key genes related to lipid metabolism in the liver of broiler chickens (p < 0.05). Furthermore, 16S rRNA gene sequencing revealed that HMB supplementation could greatly change the richness, diversity, and composition of the broiler gut microbiota, and the Bacteroidetes relative abundance at the phylum level and the Alistipes relative abundance at the genus level were affected (p < 0.05). Correlation analysis further suggested a strong association between Bacteroidetes relative abundance and lipid metabolism-related parameters (p < 0.05). Together, these data suggest that 0.10% HMB supplementation could inhibit hepatic fat deposition via regulating gut microbiota in broilers.

Genomic Analysis of Visceral Fat Accumulation in Holstein Cows

Visceral fat is related to important metabolic processes, including insulin sensitivity and lipid mobilization. The goal of this study was to identify individual genes, pathways, and molecular processes implicated in visceral fat deposition in dairy cows. Data from 172 genotyped Holstein cows classified at slaughterhouse as having low (n = 77; omental fold <5 mm in thickness and minimum fat deposition in omentum) or high (n = 95; omental fold ≥20 mm in thickness and marked fat deposition in omentum) omental fat were analyzed. The identification of regions with significant additive and non-additive genetic effects was performed using a two-step mixed model-based approach. Genomic scans were followed by gene-set analyses in order to reveal the genetic mechanisms controlling abdominal obesity. The association mapping revealed four regions located on BTA19, BTA20 and BTA24 with significant additive effects. These regions harbor genes, such as SMAD7, ANKRD55, and the HOXB family, that are implicated in lipolysis and insulin tolerance. Three regions located on BTA1, BTA13, and BTA24 showed marked non-additive effects. These regions harbor genes MRAP, MIS18A, PRNP and TSHZ1, that are directly implicated in adipocyte differentiation, lipid metabolism, and insulin sensitivity. The gene-set analysis revealed functional terms related to cell arrangement, cell metabolism, cell proliferation, cell signaling, immune response, lipid metabolism, and membrane permeability, among other functions. We further evaluated the genetic link between visceral fat and two metabolic disorders, ketosis, and displaced abomasum. For this, we analyzed 28k records of incidence of metabolic disorders from 14k cows across lactations using a single-step genomic BLUP approach. Notably, the region on BTA20 significantly associated with visceral fat deposition was also associated with the incidence of displaced abomasum. Overall, our findings suggest that visceral fat deposition in dairy cows is controlled by both additive and non-additive effects. We detected at least one region with marked pleiotropic effects affecting both visceral fat accumulation and displaced abomasum.

Identification and Functional Verification Reveals that miR-195 Inhibiting THRSP to Affect Fat Deposition in Xinyang Buffalo

The buffalo population is extensive in China, but its meat quality is relatively inferior. Therefore, improving meat quality should be one of the breeding goals. microRNAs (miRNAs) play an essential regulatory role in the post-transcriptional expression of genes. Some studies have reported their function regulating genes related to fat deposition and adipocyte differentiation in cattle, but there is limited reports in buffalo. We performed small RNA transcriptome sequencing of Xinyang buffalo adipose tissue between calves and adults in this study. As a result, 282 mature miRNAs were significantly differentially expressed, and co-expression analysis showed that 454 miRNAs were significantly associated with developmental stages. Target gene identification, GO (gene ontology) annotation, and KEGG analysis of miRNAs showed that miR-195, miR-192, and miR-24-3p could target key genes for lipogenesis and thus regulate adipose deposition and differentiation. Among them, miR-195 was significantly upregulated in adipose tissue and induced adipocytes of adult buffaloes, and its overexpression significantly inhibited lipid accumulation in primary adipocytes. Dual-luciferase reporter gene analysis showed that miR-195 reduced the expression of thyroid hormone response protein (THRSP) by targeting its 3′ untranslated terminal region, suggesting that miR-195 may inhibit lipid accumulation in adipocytes by regulating THRSP. The results confirmed the reliability of predictive screening of miRNAs and provided theoretical support for buffalo fattening.

Exploring the Ruminal Microbial Community Associated with Fat Deposition in Lambs

Microbial communities of the sheep rumen have been studied extensively; however, their involvement in the regulation of fat deposition is unknown. Herein, we aimed to identify the correlations among fat deposition-related phenotypes and the effect of microbiota on changes in body fat accumulation. The rumen microbiota of 141 lambs was profiled by 16S ribosomal RNA sequencing, and the volatile fatty acids’ (VFAs’) concentrations were quantified by gas chromatography. Subsequently, the animals were grouped according to body mass index (BMI) to compare the microbiota of the rumen among the sheep with different fat deposition levels. Results further revealed differences in terms of the species abundance, diversity, and microbial composition between sheep with different fat deposition levels. Linear discriminant analysis (LDA) Effect Size (LEfSe) analysis and Random Forest (RF) regression analysis identified changes in 29 ruminal bacteria, which may be the main driver for different fat deposition.

The influence of the pre-slaughter weight of steers on their beef traits

Beef productivity of animals such indicators as breed, age of the animal at slaughter, pre-slaughter weight, and after slaughter – yield of carcass, slaughter weight and slaughter yield, morphological composition and the nature of fat deposition are characterized by. The purpose of the research was to study the influence of the pre-slaughter weight of steers of Aubrac breed on their beef traits. In order to carry out the research, three groups of animals have been formed per 15 animals in each. The 1st group included animals whose pre-slaughter weight was in the range of 425–440 kg, the 2nd group – 455–460 kg and the 3rd – 475–500 kg. The conditions of feeding and housing the animals were the same. The animals were housed in arched-type barns with free access to exercising areas. The results of the investigation of the beef productivity and quality of the Musculus longissimus in steers of Aubrac breed depending on the pre-slaughter live weight have been presented in the article. It has been found that animals with the pre-slaughter weight of more than 455 kg were characterized by higher beef traits. Steers with the pre-slaughter weight from 475 to 500 kg were characterized by higher slaughter and beef traits, in the samples of the Musculus longissimus they had a higher content of fat and amino acids. Samples of the Musculus longissimus of steers at slaughter of 455–460 kg were characterized by the higher caloric content, protein-quality indicator. It has been proposed according to the results of the research that the optimal slaughter for steers of Aubrac breed with the pre-slaughter weight is more than 455 kg.