Beef Cattle Genome Project: Advances in Genome Sequencing, Assembly, and Functional Genes Discovery.

Beef is a major global source of protein, playing an essential role in the human diet. The worldwide production and consumption of beef continue to rise, reflecting a significant trend. However, despite the critical importance of beef cattle resources in agriculture, the diversity of cattle breeds faces severe challenges, with many breeds at risk of extinction. The initiation of the Beef Cattle Genome Project is crucial. By constructing a high-precision functional annotation map of their genome, it becomes possible to analyze the genetic mechanisms underlying important traits in beef cattle, laying a solid foundation for breeding more efficient and productive cattle breeds. This review details advances in genome sequencing and assembly technologies, iterative upgrades of the beef cattle reference genome, and its application in pan-genome research. Additionally, it summarizes relevant studies on the discovery of functional genes associated with key traits in beef cattle, such as growth, meat quality, reproduction, polled traits, disease resistance, and environmental adaptability. Finally, the review explores the potential of telomere-to-telomere (T2T) genome assembly, structural variations (SVs), and multi-omics techniques in future beef cattle genetic breeding. These advancements collectively offer promising avenues for enhancing beef cattle breeding and improving genetic traits.

Responses of nutrient utilization, rumen fermentation and microorganisms to different roughage of dairy buffaloes.

Dairy buffaloes are typically fed a high-forage, low-quality diet with high fiber. These conditions result in an inherent energy and protein inefficiency. In order to make full and rational use of feed resources and improve the production level and breeding efficiency of dairy buffaloes, the effects of various roughages on nutrient digestibility, ruminal fermentation parameters, and microorganisms in dairy buffaloes were studied in this experiment. Three ternary hybrid buffaloes, with an average body weight of 365 ± 22.1 kg, were selected and fitted with permanent rumen fistulas. They were fed six different diets, each consisting of 1 kg concentrate supplement and one of six types of roughage, including alfalfa hay (A diet), oat hay (O diet), whole corn silage (W diet), king grass (K diet), sugarcane shoot silage (S diet), and rice straw hay (R diet) according to an incomplete Latin square design of 3 × 6, respectively. The pre-feeding period of each period was 12 d. From day 13 to 15 was the official experimental period. During the prefeeding period, free feed intake for each roughage was determined, and during the experiment, the roughage was fed at 90% of the voluntary feed intake. Digestion and metabolism tests were carried out using the total manure collection method to determine the feed intake and fecal output of each buffalo, and to collect feed and fecal samples for chemical analysis. On day 15, rumen fluid samples were collected two hours after morning feeding to determine rumen fermentation parameters and bacterial 16 S rRNA high-throughput sequencing was performed. The results showed that DM and OM digestibility were greatest for the W diet and lowest for the S diet. The rumen pH of the O diet was significantly greater than that of the W diet. The concentration of rumen fluid NH3-N (mg/dL) increased with increased CP content. The concentration of total volatile fatty acids (mmol/L) in the rumen decreased with increased NDF content but increased with increased NFC content. The relative abundances of Bacteroidetes, Firmicutes, and Spirochaetes were 57.03-74.84%, 14.29-21.86%, and 0.44-1.43% in the different quality roughage groups. Bacteroidetes were mainly Prevotellaceae1 and Rikenellaceae RC_gut_group with relative abundances of 30.17-45.75% and 3.23-7.82%. The relative abundance of Patescibacteria and Spirochaetes decreased with increasing roughage quality. These results provide a theoretical and practical basis for evaluating the nutritional value of dairy buffalo feed, utilizing feed resources, matching rations, feeding scientifically, and protecting animal health.

Intensive feeding alters the rumen microbiota and its fermentation parameters in natural grazing yaks.

Introduction: Amidst the challenging environmental conditions characterized by low oxygen levels and cold temperatures on the plateau, alterations in nutrient supply emerge as pivotal factors influencing the survival and reproduction of yaks. Intensive feeding stands out as a substantial mechanism for nutrient provision, initiating discernible changes in the host's rumen flora. Within the extreme natural conditions prevailing in the plateau area of northwest Yunnan, China, there exists a con-strained comprehension of the variations in rumen microflora, fermentation parameters, and growth responses exhibited by yaks subjected to intensive feeding. Methods: This study employs 16S rRNA and ITS sequencing methods to scrutinize the rumen flora of yaks engaged in both natural grazing (G) and intensive feeding (F) on the plateau. Results: The outcomes unveil that, during the severe winter season, yaks adeptly modulate the abundance and diversity of rumen flora in response to dietary modifications under intensive feeding, aiming to optimize the efficient utilization of dietary fiber and energy. Principal Coordinate Analysis (PCoA) illustrates a substantial alteration in the rumen microbial community of naturally grazing yaks when exposed to intensive feeding. The natural grazing group manifests a higher prevalence of Firmicutes and Bacteroidetes, while the intensive feeding group exhibits heightened levels of Prevotella in the rumen. The Rikenellaceae _ RC9 _ gut_ group, associated with mycobacteria, prevails more abundantly in the natural grazing setting. PICRUSt2 analysis indicates that intensive feeding induces bacterial gene overexpression linked to protein metabolism. Rumen fungi showcase heightened diversity under intensification. Intensive feeding results in an augmented abundance of non-fiber-degrading bacteria and semi-fiber-degrading bacteria, accompanied by elevated concentrations of Volatile Fatty Acids (VFA). Discussion: These findings yield novel insights into the shifts in the rumen microflora of yaks acclimated to intensive feeding in high-altitude environments, provide an important reference for the nutritional regulation of supplemental feeding of natural grazing yaks in the cold season, ultimately contributing to their enhanced growth.

Unveiling the common loci for six body measurement traits in Chinese Wenshan cattle.

Introduction: Body measurement traits are integral in cattle production, serving as pivotal criteria for breeding selection. Wenshan cattle, a local breed in China's Yunnan province, exhibit remarkable genetic diversity. However, the molecular mechanisms regulating body measurement traits in Wenshan cattle remain unexplored. Methods: In this study, we performed a genome-wide association method to identify genetic architecture for body height body length hip height back height (BAH), waist height and ischial tuberosity height using the Bovine 50 K single nucleotide polymorphism Array in 1060 Wenshan cattles. Results: This analysis reveals 8 significant SNPs identified through the mixed linear model (MLM), with 6 SNPs are associated with multiple traits and 4 SNPs are associated with all 6 traits. Furthermore, we pinpoint 21 candidate genes located in proximity to or within these significant SNPs. Among them, Scarb1, acetoacetyl-CoA synthetase and HIVEP3 were implicated in bone formation and rarely encountered in livestock body measurement traits, emerge as potential candidate genes regulating body measurement traits in Wenshan cattle. Discussion: This investigation provides valuable insights into the genetic mechanisms underpinning body measurement traits in this unique cattle breed, paving the way for further research in this domain.

Differences in composition and diversity of rumen fungi in buffalo fed different diets.

The rumen is a complex ecosystem containing a variety of fungi, which are crucial for the digestive activities of ruminants. Previous research on rumen fungi has mainly focused on anaerobic fungi, given the rumen's reputation as a mainly anaerobic environment. The objective of this study was to investigate rumen fungal diversity and the presence of aerobic fungi in buffalo fed on different diets. Three adult buffaloes were used as experimental animals. Alfalfa hay, oat hay, whole corn silage, sugarcane shoot silage, fresh king grass, dried rice straw, and five kinds of mixed diets with concentrate to roughage ratios of 20:80, 35:65, 50:50, 65:35, and 80:20 were used as the experimental diets. The experimental animals were fed different diets for 22 days. Rumen fluid was collected from the rumen fistula for ITS (Internal Transcribed Spacer) sequencing 2 h after feeding on the morning of day 22. The results indicate the presence of large quantities of aerobic fungi in the rumen of the buffaloes 2 h after feeding and suggest that Ascomycota and Basidiomycota are the dominant fungal groups under different feeding conditions. The study also identified 62 different fungal types, which showed significant differences among the 11 experimental diets.

Exploring the elevation dynamics of rumen bacterial communities in Barn feeding cattle from 900 to 3,600 meters by full-length 16S sequencing.

The diversity and abundance of rumen microorganisms serve as indicators not only of the host's digestive and metabolic capacity but also of its health status. The complex microbial communities in the rumen are influenced to varying degrees by environmental adaptability. In this study, we collected 24 rumen fluid samples from 24 healthy male cattle in three regions of Yunnan, China. Using 16S rRNA amplicon sequencing data analysis, we examined the variations in rumen microorganisms among cattle fed at altitudes of 900 m, 1800 m, and 3,600 m. Altitude-related environmental factors did not surpass phylogeny as the main driving force behind the convergent evolution of yellow cattle rumen microbiome composition. However, they did have an impact on the alpha diversity of the rumen microbiome and the coevolution of the core microbiome. The change in altitude noticeably influenced the diversity and richness of the rumen microbiota, highlighting the environmental effect of altitude. As altitude increased, there was an observed increase in the abundance of Firmicutes and Bacteroidetes, while the abundance of ruminal Proteobacteria and Kiritimatiellaeota decreased. Importantly, at the genus level, the core genus exhibited distinct dynamic changes as altitude increased. Ruminants exhibit the ability to adapt their gut type in accordance with altitude, thereby optimizing energy utilization, especially in high-altitude settings. These discoveries offer valuable insights into the coevolution of host-microbe interactions during ruminant adaptation to various altitudinal environments.

Exploring the temporal dynamics of rumen bacterial and fungal communities in yaks (Bos grunniens) from 5 days after birth to adulthood by full-length 16S and 18S rRNA sequencing.

The rumen of ruminants is inhabited by complex and diverse microorganisms. Young animals are exposed to a variety of microorganisms from their mother and the environment, and a few colonize and survive in their digestive tracts, forming specific microflora as the young animals grow and develop. In this study, we conducted full-length sequencing of bacterial and fungal communities in the rumen of pastured yaks of different ages (from 5 days after birth to adulthood) using amplified sequencing technology. The results showed that the rumen microflora of Zhongdian yaks changed gradually from 5 to 180 days after birth and tended to stabilize at 2 years of age. The rumen of adult yaks was the most suitable for the growth and reproduction of most bacteria. Bactria diversity of the yak rumen increased gradually from 5 days after birth to adulthood. With the growth of yaks, different dominated bacteria were enriched in different groups, but Prevotella remained highly abundant in all groups. The yak rumen at 90 days of age was the most suitable for the growth and reproduction of most fungi, and 90 days of age could be a cut-off point for the distribution of fungal communities. Fungal Thelebolus was the firstly reported in yak rumen and was enriched in the yak rumen of 90 days after birth. The most abundant and balanced fungal genera were found in adult yaks, and most of them were only detected in adult yaks. Our study reported on the rumen bacterial and fungal communities of Zhongdian yaks grazed at different ages and provided insights into the dynamic changes of dominant microflora with yak growth.

Effects of king grass and rice straw hay on apparent digestibility and ruminal microorganisms of buffalo.

The purpose of this study was to explore the effects of Rice straw and King grass on apparent digestibility, ruminal bacterial, and fungus composition in buffaloes. Three ruminal fistulated buffaloes were used in a 3 × 2 Latin square design. The dietary treatments were king grass and straw hay. Experimental animals were kept in individual pens and concentrate was offered at 1 kg/d while roughage was fed ad libitum. Each period lasted for 15d, with the first 12d for an adaptation period, followed by a 3-day formal trial period. King grass has higher digestibility of protein. Rice straw has higher digestibility to cellulose. The results showed that when buffaloes were fed king grass and straw, Bacteroidetes were dominant in the rumen normal flora, but firmicutes were not. In addition, the results of this experiment suggest that increasing protein content in diets may be beneficial to increase the relative abundance of Proteobacteria. Similarly, higher dietary fiber content may be beneficial for increasing relative abundance of Prevotella and Staphylococcus. The dominant fungi in ruminal fluid 2 h after ingestion were aerobic fungi. These aerobic fungi most likely entered the rumen with food. Whether and how long aerobic fungi can survive in the rumen needs more research.

Exploration of the effects of altitude change on bacteria and fungi in the rumen of yak (Bos grunniens).

The yak (Bos grunniens) is a ruminant animal with strong regional adaptability. However, little is known about the adaptation of the rumen microbial community of yaks at different altitudes and the adaptation mechanism of the host and intestinal microorganisms to the habitat. We investigated the adaptability of the rumen microorganisms of yaks at high and low altitudes. We also compared and analyzed the abundance and diversity of core microorganisms and those that varied between different animals. The aim was to compare the rumen bacterial and fungal communities of grazing yak living at two elevations. Bacteroidetes, Firmicutes, Ascomycota, and Chytridiomycota were the dominant bacteria in the plateau and low-altitude regions. Significant differences between the dominant microorganisms in the rumen of yaks were evident in the two regions. The proportion of fiber-degrading bacteria was significantly different between yaks dwelling at high-altitude and low-altitude regions. The abundance of starch-degrading bacteria was not significantly different with altitude. Species clustering similarity analysis showed that the rumen microorganisms in the two areas were obviously isolated and clustered into branches. Functional prediction showed significant differences in rumen microbial methane metabolism, starch and sucrose metabolism, ion-coupled transporter and bacterial secretion system at different altitudes. Overall, the results of this study improved our understanding of the abundance and composition of microorganisms in the rumen of yak at different altitudes.

Host and altitude factors affect rumen bacteria in cattle.

There are many kinds of microorganisms in the gastrointestinal tract of mammals, some of which are closely related to the host. Rumen microorganisms are essential for normal physiological activities of their host by decomposing plant crude lignin and providing essential nutrients. The composition and diversity of this microbial population are influenced by the host, environment, and diet. Despite its importance, little is known about the effects of factors such as altitude variation on rumen microbial population abundance and diversity in different ruminants. Here, we described the changes in overall rumen bacteria in four groups of cattle, including the Zhongdian yellow cattle and Zhongdian yaks, grazing at high altitudes (3600 m); the Jiangcheng yellow cattle and Jiangcheng buffalo were kept at an altitude of 1100 m. We found that there was a significant difference in rumen bacterial abundance of the Zhongdian yellow cattle and Zhongdian yaks at high altitude and there was obvious homogeneity in rumen bacterial abundance and diversity in the Jiangcheng yellow cattle and Jiangcheng buffalo at low altitude. Therefore, our research concluded that under the same dietary environment, there were differences in the abundance and diversity of certain bacteria in the rumen of different breeds of cattle, indicating that host genetic factors and intestinal microorganisms related to altitudinal variation had a greater influence on rumen bacterial abundance in the cattle.

Directed modification of a ruminal cellulase gene (CMC-1) from a metagenomic library isolated from Yunnan gayal (Bos frontalis).

Gayal (Bos frontalis) of the Yunnan region is well adapted to harsh environmental conditions. Its diet consists predominantly of bamboo, reeds, and woody plants, suggesting that the rumen of this species contains many fiber-degrading bacteria and cellulases. The aim of this study was to identify and modify specific cellulases found in the gayal rumen. In the present study, a directed evolution strategy of error-prone PCR was employed to improve the activity or optimal temperature of a cellulase gene (CMC-1) isolated from gayal rumen. The CMC-1 gene was heterologously expressed in Escherichia coli (E. coli) BL21, and the recombinant CMC-1 protein hydrolyzed carboxyl methyl cellulose (CMC) with an optimal activity at pH 5.0 and 50 °C. A library of mutated ruminal CMC-1 genes was constructed and a mutant EP-15 gene was identified. Sequencing analysis revealed that EP-15 and CMC-1 belonged to the glycosyl hydrolase family 5 (GHF5) and had the highest homology to a cellulase (Accession No. WP_083429257.1) from Prevotellaceae bacterium, HUN156. There were similar predicted GH5 domains in EP-15 and CMC-1. The EP-15 gene was heterologously expressed and exhibited cellulase activity in E. coli BL21 at pH 5.0, but the optimum temperature for its activity was reduced from that of CMC-1 (50 °C) to 45 °C, which was closer to the physiological temperature of the rumen (40 °C). The cellulase activity of EP-15 was about two times higher than CMC-1 at 45 °C or PH 5.0, and also was more stable in response to temperature and pH changes compared to CMC-1. This study successfully isolated and modified a ruminal cellulase gene from metagenomics library of Yunnan gayal. Our findings may obtain a useful cellulase in future applications and present the first evidence of modified cellulases in the gayal rumen.