LAUSR

Mastitis is a complex and multifactorial disease that leads to chemical, physical and bacteriological changes in milk and is associated with great economic losses. This study was carried out in lactating cows to investigate the effect of subclinical mastitis (SCM) on milk production through estimation immunological and biochemical characteristics of milk. Therefore, a total 200 apparently-healthy lactating cows were selected randomly from different areas in Baghdad and Maysan provinces during April to July 2021, and direct collection 100 ml of fresh milk from the active-quarter (s) of each study cow. Examination of milk samples by California mastitis test (CMT), IgG concentration in milk by ELISA method and changes in biochemical parameters and enzymatic parameters to determine the prevalence of SCM. CMT test showed that the prevalence of SCM was 41.5% with significant increases in mild degree of severity (61.45%). IgG antibodies increased significantly in positive cows (4.92± 0.21 µg/ml). Significant prevalence of infection was seen in cows of ≥ 5 years age old compared to <5 years, crossbred compared to natives, and in cows of lowered milk production without udder/ milk abnormalities compared to normal, but not significant difference between study regions (Baghdad and Maysan). Result of biochemical and enzymatic parameters showed significant increases in concentration of Cl, FFA and Na, and reduction in LAC and TP, but not in Ca and K. The pH of mastitis milk was significantly higher. Although, no significant difference was observed in values of ALT and LDH, AST was increased in mastitis milk. In conclusion, this study appears as the first report of estimated the concentration of IgG in mastitis milk samples in Iraq. Increases in concentration of SSCs and IgG in milk can apply in detection of intra-mammary infections.