Exploring factors associated with bulk tank milk urea nitrogen in Central Thailand

Nutrition, gastrointestinal microorganisms and metabolites in mastitis occurrence and control

Mastitis affects almost all mammals including humans and dairy cows. In the dairy industry, bovine mastitis is a disease with a persistently high incidence, causing serious losses to the health of cows, the quality of dairy products, and the economy of dairy farms. Although local udder infection caused by the invasion of exogenous pathogens into the mammary gland was considered the main cause of mastitis, evidence has been established and continues to grow, showing that nutrition factors and gastrointestinal microbiome (GM) as well as their metabolites are also involved in the development of mammary inflammatory response. Suboptimal nutrition is recognized as a risk factor for increased susceptibility to mastitis in cattle, in particular the negative energy balance. The majority of data regarding nutrition and bovine mastitis involves micronutrients. In addition, the dysbiotic GM can directly trigger or aggravate mastitis through entero-mammary gland pathway. The decreased beneficial commensal bacteria, lowered bacterial diversity, and increased pathogens as well as proinflammatory metabolites are found in both the milk and gastrointestinal tract of mastitic dairy cows. This review discussed the relationship between the nutrition (energy and micronutrient levels) and mastitis, summarized the role of GM and metabolites in regulating mastitis. Meanwhile, several non-antibiotics strategies were provided for the prevention and alleviation of mastitis, including micronutrients, probiotics, short-chain fatty acids, high-fiber diet, inulin, and aryl hydrocarbon receptor.

Coupling 16S rDNA Sequencing and Untargeted Mass Spectrometry for Milk Microbial Composition and Metabolites from Dairy Cows with Clinical and Subclinical Mastitis

The internal environment of the cow's udder directly affects the udder health and milk quality. 16S rDNA sequencing and liquid chromatography-mass spectrometry (LC-MS) methods were used to investigate the significant differences in milk microbial diversity and metabolites among cows that are healthy (H) and those suffering from subclinical mastitis (SM) and clinical mastitis (CM). Results uncovered more than 16 and 192 differently abundant microbiota at the phylum and genus levels, respectively, and 673 different levels of metabolites enriched in 20 pathways in milk among the 3 groups. This study revealed the positive relevance between Staphylococcus and Streptococcus and ceramide in milk from CM cows. Similarly, Acinetobacter and Corynebacterium were positively associated with testosterone glucuronide and 5-methyl-tetrahydrofolate, in milk from SM cows. On the basis of the combined analysis of microbiome and metabolome, this study indicated that, apart from the exogenous pathogens, some beneficial symbiotic bacteria, such as Dietzia, Aeromicrobium, Alistipes, and Sphingobacterium, rarely reported in milk have been found to be significantly reduced during mastitis.

Evaluation of the milk urea content in relation to milk production and composition in dairy cows

The aim of this study was to evaluate the milk urea content along with the dynamics of lactation and milk components in production dependency in Holstein dairy cows. Evaluation of daily milk yield in relation to milk urea presented a positive regression dependency, which was the strongest in early lactation (r = 0.860; P < 0.001), decreasing in mid lactation (r = 0.329; P < 0.001) and late lactation (r = 0.261; P < 0.001). Evaluation of milk protein in relation to milk urea showed a negative regression dependency, which was the strongest in early lactation (r = -0.850; P < 0.001), decreasing in mid lactation (r = -0.819; P < 0.001) and late lactation (r = -0.679; P < 0.001). The somatic cell counts in relation to milk urea confirmed a negative regression dependency in early lactation (r = -0.635; P < 0.05) and mid lactation (r = -0.818; P < 0.05), but no significance was found in late lactation. The results of the study confirm the influence of production factors (milk quantity and milk components) on the milk urea content. Dependencies found between the production, milk components and milk urea are applicable for the evaluation of protein nutrition and metabolic transformation of nutrients in dairy cows.