Advances in single-cell transcriptomics in animal research.

Understanding biological mechanisms is fundamental for improving animal production and health to meet the growing demand for high-quality protein. As an emerging biotechnology, single-cell transcriptomics has been gradually applied in diverse aspects of animal research, offering an effective method to study the gene expression of high-throughput single cells of different tissues/organs in animals. In an unprecedented manner, researchers have identified cell types/subtypes and their marker genes, inferred cellular fate trajectories, and revealed cell‒cell interactions in animals using single-cell transcriptomics.

Dynamic fecal microenvironment properties enable predictions and understanding of peripartum blood oxidative status and nonesterified fatty acids in dairy cows.

The transition period in dairy cows is a critical stage and peripartum oxidative status, negative energy balance (NEB), and inflammation are highly prevalent. Fecal microbial metabolism is closely associated with blood oxidative status and nonesterified fatty acids (NEFA) levels. Here, we investigated dynamic changes in total oxidative status markers and NEFA in blood, fecal microbiome, and metabolome of 30 dairy cows during transition (-21, -7, +7, +21 d relative to calving).

The hindgut microbiome contributes to host oxidative stress in postpartum dairy cows by affecting glutathione synthesis process.

Background: Dairy cows are susceptible to postpartum systemic oxidative stress (OS), which leads to significant production loss and metabolic disorders. The gut microbiota has been linked to host health and stress levels. However, to what extent the gut microbiota is associated with postpartum OS remains unknown.

Age- and Microbiota-Dependent Cell Stemness Plasticity Revealed by Cattle Cell Landscape.

Newborn ruminants are considered functionally monogastric animals. The poor understanding of cellular differences between newborn and mature ruminants prevents the improvement of health and performance of domestic ruminants. Here, we performed the single-cell RNA sequencing on the rumen, reticulum, omasum, abomasum, duodenum, jejunum, ileum, cecum, colon, rectum, liver, salivary gland, and mammary gland from newborn and adult cattle.

Gut microbiome is linked to functions of peripheral immune cells in transition cows during excessive lipolysis.

Background: Postpartum dairy cows experiencing excessive lipolysis are prone to severe immunosuppression. Despite the extensive understanding of the gut microbial regulation of host immunity and metabolism, its role during excessive lipolysis in cows is largely unknown. Herein, we investigated the potential links between the gut microbiome and postpartum immunosuppression in periparturient dairy cows with excessive lipolysis using single immune cell transcriptome, 16S amplicon sequencing, metagenomics, and targeted metabolomics.

Microbiota-host crosstalk in the newborn and adult rumen at single-cell resolution.

Background: The rumen is the hallmark organ of ruminants, playing a vital role in their nutrition and providing products for humans. In newborn suckling ruminants milk bypasses the rumen, while in adults this first chamber of the forestomach has developed to become the principal site of microbial fermentation of plant fibers. With the advent of single-cell transcriptomics, it is now possible to study the underlying cell composition of rumen tissues and investigate how this relates the development of mutualistic symbiosis between the rumen and its epithelium-attached microbes.

Cross-tissue single-cell transcriptomic landscape reveals the key cell subtypes and their potential roles in the nutrient absorption and metabolism in dairy cattle.

Introduction: Dairy cattle are a vitally important ruminant in meeting the demands for high-quality animal protein production worldwide. The complicated biological process of converting human indigestible biomass into highly digestible and nutritious milk is orchestrated by various tissues. However, poorly understanding of the cellular composition and function of the key metabolic tissues hinders the improvement of health and performance of domestic ruminants.

Supplementing -carbamoylglutamate in late gestation increases newborn calf weight by enhanced placental expression of mTOR and angiogenesis factor genes in dairy cows.

The objective of this study was to investigate whether supplementation with -carbamoylglutamate (NCG) to cows during late gestation alters uteroplacental tissue nutrient transporters, calf metabolism and newborn weight. Thirty multiparous Chinese Holstein cows were used in a randomized complete block design experiment. During the last 28 d of pregnancy, cows were fed a diet without (CON) or with NCG (20 g/d per cow).

Multi-omics revealed the effects of rumen-protected methionine on the nutrient profile of milk in dairy cows.

Cow's milk is a highly-nutritious dairy product part of human diet worldwide. Rumen-protected methionine (RPM) is widely used to improve lactation performance of dairy cows, but understanding of the effects of RPM on milk nutrients composition are still limited. In this study, twenty mid-lactating dairy cows were supplemented with 20 gm/day RPM for 8 weeks to investigate the responses of milk nutritional composition to RPM.

Dietary supplementation with N-carbamoylglutamate initiated from the prepartum stage improves lactation performance of postpartum dairy cows.

The objective of this study was to investigate the effects of supplementing N-carbamoylglutamate (NCG), an Arg enhancer, on amino acid (AA) supply and utilization and productive performance of early-lactating dairy cows. Thirty multiparous Chinese Holstein dairy cows were randomly divided into control (CON,  = 15) and NCG (CON diet supplemented with NCG at 20 g/d per cow,  = 15) groups at 4 wk before calving. Diets were offered individually in tie-stalls, and NCG was supplemented by top-dress feeding onto total mixed ration for the NCG group.