Chemical markers for rumen methanogens and methanogenesis

Peer reviewedPublisher PD

Light microscopic observations of the ruminal papillae of cattle on diets with divergent forage to cereal ratios

High levels of supplementation with cereal increases production rates in cattle but can increase incidence of disease, ranging from mild indigestion to acute ruminal acidosis and death. Therefore, there is motivation to determine biological markers which can be used to identify whether animals have been, or are being fed, sufficient or excessive cereals. This study aimed to describe light microscopic findings from animals being fed diverse dietary cereal proportions and to test the performance of a novel rumen epithelial scoring system. Rumen wall tissue samples were obtained from the abattoir from 195 cattle from 11 Scottish farms and processed for histological examination. Light microscopic examination was used to characterise ruminal epithelial response to dietary challenge. Secondary objectives included describing the distribution of immune-related cells in bovine ruminal epithelium and assessing the use of a modified Elastin Martius Scarlet Blue stain (EMSB) for histological examination of the rumen epithelium. Cells staining positive for cluster of differentiation 3 were distributed mainly in the lower layers of the stratum basale and were found in higher densities in animals offered lower cereal proportion diets. Cells staining positive for major histocompatibility complex class 2 (MHCII) were most common in perivascular locations and in the junction between the lower stratum basale and the propria-submucosa. The density of MHCII positive staining cells was higher in animals on lower cereal diets. The level of supplementation with cereal was also associated with the thickness of the stratum corneum (SCT) and stratum granulosum (SGT), the integrity of the stratum corneum and sloughing of cornified cells. There were no advantages in using EMSB stain over haematoxylin and eosin (H and E) in this scoring system. We concluded that a scoring system that included only SCT, SGT and a measure of the loss of appearance of intercellular space allowed differentiation of groups of animals according to the level of cereal supplementation

A draft human pangenome reference

Here the Human Pangenome Reference Consortium presents a first draft of the human pangenome reference. The pangenome contains 47 phased, diploid assemblies from a cohort of genetically diverse individuals. These assemblies cover more than 99% of the expected sequence in each genome and are more than 99% accurate at the structural and base pair levels. Based on alignments of the assemblies, we generate a draft pangenome that captures known variants and haplotypes and reveals new alleles at structurally complex loci. We also add 119 million base pairs of euchromatic polymorphic sequences and 1,115 gene duplications relative to the existing reference GRCh38. Roughly 90 million of the additional base pairs are derived from structural variation. Using our draft pangenome to analyse short-read data reduced small variant discovery errors by 34% and increased the number of structural variants detected per haplotype by 104% compared with GRCh38-based workflows, which enabled the typing of the vast majority of structural variant alleles per sample

Using archaeol to investigate the location of methanogens in the ruminant digestive tract

The quantification of archaeol, a methanogen membrane lipid, may provide an alternative method to estimate methanogen abundance. The focus of this study was to determine thelocation of methanogens in the ruminant digestive tract using this biomarker. Archaeol was quantified in samples obtained from four lactating cows with rumen cannulae that grazed on either white clover (WC) or perennial ryegrass (PRG) in a changeover design study with three 3-week periods. Faeces were collected over the final 5 d of each period and total rumen contents (TRC) were obtained on the final 2 days (day 1: 9 am; day2: 3 pm). Solid-associated microbes (SAM) and liquid-associated microbes (LAM) were also isolated from the TRC. Concentrations of archaeol in the TRC showed a significant diet by time interaction, which may be related to diurnal grazing patterns and different rumen conditions associated with PRG or WC diets. There was significantly more archaeol associated with SAM than LAM, which may reflect difficulties of methanogen proliferation in the liquid phase. Faeces had higher concentrations of archaeol than SAM and LAM which was unexpected, although, losses of methanogens may have occurred during isolation (i.e., attachment to protozoa and very small particles), or the methanogens associated with SAM may have been underestimated. There was no significant relationship between faecal and TRC archaeol concentrations. Finally, there was a significant positive relationship between rumen pH and concentrations of archaeol in SAM and LAM,which may be caused by pH and/or WC diet effects. In conclusion, archaeol is potentially a useful alternative marker for determining the abundance of methanogens in the ruminant digestive tract. This work has also highlighted the difficulties associated with methanogen quantification from microbial isolates, and the need for more representative rumen sampling in future studies

Postmortem observations on rumen wall histology and gene expression and ruminal and caecal content of beef cattle fattened on barley-based rations:Postmortem ruminal findings in beef cattle

Sub-acute ruminal acidosis (SARA) can reduce the production efficiency and impair the welfare of cattle, potentially in all production systems. The aim of this study was to characterise measurable postmortem observations from divergently managed intensive beef finishing farms with high rates of concentrate feeding. At the time of slaughter, we obtained samples from 19 to 20 animals on each of 6 beef finishing units (119 animals in total) with diverse feeding practices, which had been subjectively classified as being high risk (three farms) or low risk (three farms) for SARA on the basis of the proportions of barley, silage and straw in the ration. We measured the concentrations of histamine, lipopolysaccharide (LPS), lactate and other short-chain fatty acids (SCFAs) in ruminal fluid, LPS and SCFA in caecal fluid. We also took samples of the ventral blind sac of the rumen for histopathology, immunohistopathology and gene expression. Subjective assessments were made of the presence of lesions on the ruminal wall, the colour of the lining of the ruminal wall and the shape of the ruminal papillae. Almost all variables differed significantly and substantially among farms. Very few pathological changes were detected in any of the rumens examined. The animals on the high-risk diets had lower concentrations of SCFA and higher concentrations of lactate and LPS in the ruminal fluid. Higher LPS concentrations were found in the caecum than the rumen but were not related to the risk status of the farm. The diameters of the stratum granulosum, stratum corneum and of the vasculature of the papillae, and the expression of the gene TLR4 in the ruminal epithelium were all increased on the high-risk farms. The expression of IFN-γ and IL-1β and the counts of cluster of differentiation 3 positive and major histocompatibility complex class two positive cells were lower on the high-risk farms. High among-farm variation and the unbalanced design inherent in this type of study in the field prevented confident assignment of variation in the dependent variables to individual dietary components; however, the CP percentage of the total mixed ration DM was the factor that was most consistently associated with the variables of interest. Despite the strong effect of farm on the measured variables, there was wide inter-animal variation

Speaking the same language: can the Sustainable Development Goals translate the needs of inland fisheries into irrigation decisions?

Irrigated agriculture and inland fisheries both make important contributions to food security, nutrition, livelihoods and wellbeing. Typically, in modern irrigation systems, these components operate independently. Some practices, commonly associated with water use and intensification of crop production can be in direct conflict with and have adverse effects on fisheries. Food security objectives may be compromised if fish are not considered in the design phases of irrigation systems. The 2030 Agenda for Sustainable Development provides a framework that can serve as a backdrop to help integrate both sectors in policy discussions and optimise their contributions to achieving the Sustainable Development Goals (SDGs). Inland fisheries systems do play an important role in supporting many SDG objectives, but these contributions can sometimes be at odds with irrigated agriculture. Using case studies of two globally important river catchments, namely the Lower Mekong and Murray–Darling basins, we highlight the conflicts and opportunities for improved outcomes between irrigated agriculture and inland fisheries. We explore SDG 2 (Zero Hunger) as a path to advance our irrigation systems as a means to benefit both agriculture and inland fisheries, preserving biodiversity and enhancing the economic, environmental and social benefits they both provide to people

A strategic use of the communication mix in the destination image-formation process

National tourist offices and tourism stakeholders are challenged to maintain and secure travel markets. Travelers are constantly bombarded with travel marketing messages. Compounding the challenge is a lack of research on effective, efficient, and optimal methods in convincing tourists to travel to a particular destination. To address this literature gap, a questionnaire survey on destination brand image research was conducted on outbound travelers from four major cities, examining their image perceptions of Macao and the degree of influence that various information sources had on destination selection. Results show that a communication mix strategy could be designed to more effectively manage tourist destination image perceptions. A cross-tabulation of the data revealed that the information sources affecting travel destination choice had varying levels of influence. A "Communication Effectiveness Grid" (CEG) was conceptualized from the research with quadrants indicating marketing resource effectiveness. The CEG has significant implications for destinations with limited budgets wishing to influence travelers