Effects of pathogen diversity, farm type, and parity number on somatic cell profiles and histamine levels in milk and ultra-filtration white brined cheese from dairy cattle

This study analyzed the effects of pathogen diversity (PCR − , PCR +1 , PCR +2 , PCR +3 ), farm type (industrial, semi-industrial, traditional), and parity number (first, third, fifth lactation) on somatic cell profiles, including Log somatic cell count ( SCC ), polymorphonuclear cells ( PMNs ), lymphocytes, and histamine levels in milk from Iranian dairy cattle. Additionally, it examined histamine content in ultra-filtration ( UF )-white brined cheese after six months of storage. Results showed increased Log SCC and PMNs, while lymphocytes decreased. Higher pathogen diversity increased milk histamine content from 0.11 to 0.55 ppm. Industrial farms had the lowest Log SCC and PMN percentages due to better hygiene practices. Furthermore, the first parity number exhibited the lowest Log SCC and PMN percentages, indicating an enhanced immune status. Cheese produced from cows on industrial farms (PCR − ) had the lowest histamine levels at 1.10 ppm, while cheese from cows on traditional farms (PCR +3 ) exhibited the highest levels at 25.31 ppm. Additionally, cheese from first-parity milking cows (PCR − ) had a histamine level of 1.20 ppm, compared to 20.31 ppm in cheese from fifth-parity milking cows (PCR +3 ). The study highlights the importance of strict hygiene and pathogen management, especially for first-parity cows and industrial farms, to lower histamine levels in cheese production. • Novel insights on pathogen diversity's impact on milk & cheese SCC and histamine. • Pathogen diversity increased milk log SCC, PMN, macrophage & decreased lymphocyte. • First study linking parity number and farm type to histamine levels in cheese. • Industrial vs. traditional farms resulted in lower milk SCC & cheese histamine content. • First vs. fifth parity number resulted in lower milk SCC & cheese histamine content.