Postbiotics, which comprise inanimate microorganisms or their constituents, have recently gained significant attention for their potential health benefits. Extensive research on postbiotics has uncovered many beneficial effects on hosts, including antioxidant activity, immunomodulatory effects, gut microbiota modulation, and enhancement of epithelial barrier function. Although these features resemble those of probiotics, the stability and safety of postbiotics make them an appealing alternative. In this review, we provide a comprehensive summary of the latest research on postbiotics, emphasizing their positive impacts on both human and animal health. As our understanding of the influence of postbiotics on living organisms continues to grow, their application in clinical and nutritional settings, as well as animal husbandry, is expected to expand. Moreover, by substituting postbiotics for antibiotics, we can promote health and productivity while minimizing adverse effects. This alternative approach holds immense potential for improving health outcomes and revolutionizing the food and animal products industries.

Camel milk is a rich source of vitamin C, lactic acid bacteria (LAB), beta-caseins and milk whey proteins, including lactoferrin, lysozyme, lactoperoxidase, alpha-lactalbumin and immunoglobulin. The lactoferrin plays a key role in several physiological functions, such as conferring antioxidant, anti-microbial and anti-inflammatory functions in cells. Similarly, the camel milk alpha-lactalbumin has shown greater antioxidative activity because of its higher antioxidant amino acid residues. The antioxidant properties of camel milk have also been ascribed to the structural conformation of its beta-caseins. Upon hydrolysis, the beta-caseins lead to some bioactive peptides having antioxidant activities. Consequently, the vitamin C in camel milk has a significant antioxidant effect and can be used as a source of vitamin C when the climate is harsh. Furthermore, the lysozyme and immunoglobulins in camel milk have anti-microbial and immune regulatory properties. The LAB isolated from camel milk have a protective role against both Gram-positive and -negative bacteria. Moreover, the LAB can be used as a probiotic and may restore the oxidative status caused by various pathogenic bacterial infections. Various diseases such as cancer and hepatitis have been associated with oxidative stress. Camel milk could increase antiproliferative effects and regulate antioxidant genes during cancer and hepatitis, hence ameliorating oxidative stress. In the current review, we have illustrated the anti-microbial and antioxidant properties of camel milk in detail. In addition, the anti-cancer and anti-hepatitis properties of camel milk have also been discussed.

Bovine milk is a significant substitute for human breast milk and holds great importance in infant nutrition and health. Apart from essential nutrients, bovine milk also contains bioactive compounds, including a microbiota derived from milk itself rather than external sources of contamination. Recognizing the profound impact of bovine milk microorganisms on future generations, our review focuses on exploring their composition, origins, functions, and applications. Some of the primary microorganisms found in bovine milk are also present in human milk. These microorganisms are likely transferred to the mammary gland through two pathways: the entero-mammary pathway and the rumen-mammary pathway. We also elucidated potential mechanisms by which milk microbiota contribute to infant intestinal development. The mechanisms include the enhancing of the intestinal microecological niche, promoting the maturation of immune system, strengthening the intestinal epithelial barrier function, and interacting with milk components (e.g., oligosaccharides) via cross-feeding effect. However, given the limited understanding of bovine milk microbiota, further studies are necessary to validate hypotheses regarding their origins and to explore their functions and potential applications in early intestinal development.

Bovine mastitis, the inflammation of the mammary gland, is a contagious disease characterized by chemical and physical changes in milk and pathological changes in udder tissues. Depressed immunity and higher expression of inflammatory cytokines with an elevated milk somatic cell count can be observed during mastitis in dairy cattle. The use of somatic cell count (SCC) and somatic cell score (SCS) as correlated traits in the indirect selection of animals against mastitis resistance is in progress globally. Traditional breeding for mastitis resistance seems difficult because of the low heritability (0.10-0.16) of SCC/SCS and clinical mastitis. Thus, genetic-marker-selective breeding to improve host genetics has attracted considerable attention worldwide. Moreover, genomic selection has been found to be an effective and fast method of screening for dairy cattle that are genetically resistant and susceptible to mastitis at a very early age. The current review discusses and summarizes the candidate gene approach using polymorphisms in immune- and inflammation-linked genes (CD4, CD14, CD46, TRAPPC9, JAK2, Tf, Lf, TLRs, CXCL8, CXCR1, CXCR2, C4A, C5, MASP2, MBL1, MBL2, LBP, NCF1, NCF4, MASP2, A2M, and CLU, etc.) and their related signaling pathways (Staphylococcus aureusinfection signaling, Toll-like receptor signaling, NF-kappa B signaling pathway, Cytokine-cytokine receptor, and Complement and coagulation cascades, etc.) associated with mastitis resistance and susceptibility phenotypic traits (IL-6, interferon-gamma (IFN-γ), IL17, IL8, SCS, and SCC) in dairy cattle.

Increasing milk production is one of the key concerns in animal production. Traditional breeding has gotten limited achievement in the improvement of milk production because of its moderate heritability. Milk production traits are controlled by many genes. Thus, identifying candidate genes associated with milk production traits may provide information that can be used to enhance the accuracy of animal selection for moderately heritable traits like milk production. The genomic selection can enhance the accuracy and intensity of selection and shortening the generation interval. The genetic progress of economically important traits can be doubled with the accuracy of selection and shortening of generation interval. Genome-wide association studies (GWAS) have made possible the screening of several single nucleotide polymorphisms (SNPs) in genes associated with milk production traits in dairy cattle. In addition, RNA-sequencing is another well-established tool used to identify genes associated with milk production in dairy cattle. Although it has been widely accepted that these three methods (GWAS, RNA-seq and DNA sequencing) are considered the first step in the screening of genes, however, the outcomes from GWAS, DNA-sequencing and RNA-seq still need further verification for the establishment of bonafide causal variants via genetic replication as well as functional validation. In the current review, we have highlighted genetic markers identified (2010-to date) for their associations with milk production traits in dairy cattle. The information regarding candidate genes associated with milk production traits provided in the current review could be helpful to select the potential genetic markers for the genetic improvement of milk production traits in dairy cattle.

Mastitis (inflammation of the mammary gland) commonly occurs in dairy cattle during the periparturient period (transition period), in which dairy cattle experience physiological and hormonal changes and severe negative energy balance, followed by oxidative stress. To maintain successful lactation and combat negative energy balance (NEB), excessive fat mobilization occurs, leading to overproduction of reactive oxygen species (ROS). Excessive fat mobilization also increases the concentrations of nonesterified fatty acids (NEFA) and β-hydroxybutyric acid (BHB) during the periparturient period. In addition, the excessive utilization of oxygen by cellular respiration in the mammary causes abnormal production of oxidative stress (OS). OS impairs the immunity and anti-inflammatory efficiency of periparturient dairy cattle, increasing their susceptibility to mastitis. To alleviate oxidative stress and subsequent mastitis, antioxidants are supplemented to dairy cattle from an external source. Extensive studies have been conducted on the supplementation of selenium (Se) and vitamins E and B9 to mitigate mastitis during the transition period in dairy cattle. Altogether, in the current review, we discuss the research development on bovine mastitis and its major causes, with special emphasis on oxidative stress during the transition period. Moreover, we discuss the antioxidant, immunoregulatory, and anti-inflammatory properties of Se and vitamins E and B9 and their role in the control of bovine mastitis in periparturient dairy cattle.