Rumen microbiota has a close and intensive interaction with the ruminants. Microbiota residing in the rumen digests and ferments plant organic matters into nutrients that are subsequently utilized by the host, making ruminants a unique group of animals that can convert plant materials indigestible by humans into high-quality animal protein as meat and milk. Many studies using meta-omics technologies have demonstrated the relationships between rumen microbiome and animal phenotypes associated with nutrient metabolism. Recently, the causality and physiological mechanisms underpinning the host–microbiota interactions have attracted tremendous research interest among researchers. This review discusses the host–microbiota interactions and the factors affecting these interactions in ruminants and provides a summary of the advances in research on animal husbandry. Understanding the microbiota composition, the functions of key bacteria, and the host–microbiota interaction is crucial for the development of knowledge-based strategies to enhance animal productivity and host health.

Due to the diversity and limitation of determination methods, published data on the fatty acid (FA) compositions of different milk samples have contributed to inaccurate comparisons. In this study, we developed a high-throughput gas chromatography-mass spectrometry method to determinate milk FA, and the proposed method had satisfactory linearity, sensitivity, accuracy, and precision. We also analyzed the FA compositions of 237 milk samples from Holstein cows, Jersey cows, buffalos, yaks, humans, goats, donkeys, and camels. Holstein, Jersey, goat, and buffalo milks contained high content of even-chain saturated FA, whereas goat milk had higher content of medium- and short-chain FA (MSCFA). Yak and camel milk are potential functional foods due to their high levels of odd- and branched-chain FA and low ratios of n-6 to n-3 polyunsaturated FA (PUFA). Human milk contained lower levels of saturated FA, MSCFA, and conjugated linoleic acid, and higher levels of monounsaturated FA and PUFA. As a special nonruminant milk, donkey milk contained low levels of monounsaturated FA and high levels of PUFA and MSCFA. Based on the FA profiles of 8 types of milk, nonruminant milk was distinct from ruminant milk, whereas camel and yak milk were different from other ruminant milks and considered as potential functional foods for balanced human diet.

The milk fat globule membrane (MFGM) is a complex tri-layer membrane that wraps droplets of lipids in milk. In recent years, it has attracted widespread attention due to its excellent bioactive functions and nutritional value. MFGM contains a diverse array of bioactive lipids, including cholesterol, phospholipids, and sphingolipids, which play pivotal roles in mediating the bioactivity of the MFGM. We sequentially summarize the main lipid types in the MFGM in this comprehensive review and outline the characterization methods used to employ them. In this comprehensive review, we sequentially describe the types of major lipids found in the MFGM and outline the characterization methods employed to study them. Additionally, we compare the structural disparities among glycerophospholipids, sphingolipids, and gangliosides, while introducing the formation of lipid rafts facilitated by cholesterol. The focus of this review revolves around an extensive evaluation of the current research on lipid isolates from the MFGM, as well as products containing MFGM lipids, with respect to their impact on human health. Notably, we emphasize the clinical trials encompassing a large number of participants. The summarized bioactive functions of MFGM lipids encompass the regulation of human growth and development, influence on intestinal health, inhibition of cholesterol absorption, enhancement of exercise capacity, and anticancer effects. By offering a comprehensive overview, the aim of this review is to provide valuable insights into the diverse biologically active functions exhibited by lipids in the MFGM.

The objective was to study the effects of sugar cane molasses addition on the fermentation quality and tastes of alfalfa silage. Fresh alfalfa was ensiled with no additive (Control), 1% molasses (M1), 2% molasses (M2), and 3% molasses (M3) for 206 days. The chemical composition and fermentation characteristics of the alfalfa silages were determined, the microbial communities were described by 16S rRNA sequencing, and the tastes were evaluated using an electronic tongue sensing system. With the amount of added molasses (M), most nutrition (dry matter and crude protein) was preserved and water-soluble carbohydrates (WSC) were sufficiently used to promote the fermentation, resulting in a pH reduction from 5.16 to 4.48. The lactic acid (LA) content and LA/acetic acid (AA) significantly increased, indicating that the fermentation had turned to homofermentation. After ensiling, Enterococcus and Lactobacillus were the dominant genus in all treatments and the undesirable microbes were inhibited, resulting in lower propionic acid (PA), butyric acid (BA), and NH3-N production. In addition, bitterness, astringency, and sourness reflected tastes of alfalfa silage, while umami and sourness changed with the amount of added molasses. Therefore, molasses additive had improved the fermentation quality and tastes of alfalfa silage, and the M3 group obtained the ideal pH value (below 4.5) and the best condition for long-term preservation.

Research on mycotoxins now requires a systematic study of post-exposure organisms. In this study, the effects of aflatoxin B1 (AFB1) on biofluids biomarkers were examined with metabolomics and biochemical tests. The results showed that milk concentration of aflatoxin M1 changed with the addition or removal of AFB1. AFB1 significantly affected serum concentrations of superoxide dismutase (SOD) and malon dialdehyde (MDA), SOD/MDA, and the total antioxidant capacity. Significant differences of volatile fatty acids and NH₃-N were detected in the rumen fluid. Eighteen rumen fluid metabolites, 11 plasma metabolites, and 9 milk metabolites were significantly affected by the AFB1. These metabolites are mainly involved in the pathway of amino acids metabolism. Our results suggest that not only is the study of macro-indicators (milk composition and production) important, but that more attention should be paid to micro-indicators (biomarkers) when assessing the risks posed by mycotoxins to dairy cows.

This review highlights the importance of odd and branched chain fatty acids (OBCFAs) and dietary factors that may affect the content of milk OBCFAs in dairy cows. Historically, OBCFAs in cow milk had little significance due to their low concentrations compared to other milk fatty acids (FAs). The primary source of OBCFAs is ruminal bacteria. In general, FAs and OBCFAs profile in milk is mainly affected by dietary FAs and FAs metabolism in the rumen. Additionally, lipid mobilization in the body and FAs metabolism in mammary glands affect the milk OBCFAs profile. In cows, supplementation with fat rich in linoleic acid and α-linolenic acid decrease milk OBCFAs content, whereas supplementation with marine algae or fish oil increase milk OBCFAs content. Feeding more forage rather than concentrate increases the yield of some OBCFAs in milk. A high grass silage rate in the diet may increase milk total OBCFAs. In contrast to saturated FAs, OBCFAs have beneficial effects on cardiovascular diseases and type II diabetes. Furthermore, OBCFAs may have anti-cancer properties and prevent Alzheimer’s disease and metabolic syndrome.