Effect of subclinical intramammary infection on the milk protein profile at the quarter level in Holstein cattle

Milk and dairy products are essential agricultural sources of nutrition and milk production, depending on the consumption of dairy products, is increasing day by day with the increasing world population. Milk quality and production are of great interest in countries such as Italy, which is one of the world's most important players in the dairy industry and one of the largest producers of PDO cheeses. The bovine milk proteins establish the basis for a worldwide industry in dairy products, and as such have been intensively studied from back to nowadays. From these studies, we have a clearer awareness of the importance of these proteins in milk, milk quality, and bovine milk contains various ions, minerals, and vitamins that are essential for human health. One of the most important factors affecting milk quality is mastitis which is still one of the three main diseases that affect the profitability of the dairy industry, and accordingly, one of the other issues to be considered is udder health. Mastitis, which is one of the biggest economic problems in the dairy cattle industry from the past to the present, is the inflammation of the mammary gland. Mastitis is one of the most permanent and widely spread diseases in terms of importance to milk quality& and hygiene among dairy cattle worldwide. The aim of this study of the existing relationship between subclinical mastitis and mammary gland inflammation status, and the detailed milk protein profile 450 lactating Holstein cows with the usage of RP-HPLC (Reversed-Phase High-Performance Liquid Chromatography). This study uncovered new insights into milk protein behavior in animals with subclinical IMI at the quarter level. The IMI mainly impacted casein fractions, particularly β-CN and αs1-CN proportions. The rise in SCC appeared to drive the most significant alterations, hinting that inflammation-linked proteolytic enzymes, rather than the infection itself, play a key role in changing milk protein. These findings reinforce SCC's significance as an indicator of udder health and milk quality.