Abstract

Composite 24 h milk samples were collected for detailed milk analysis from each quarter of ten cows known to be free of intramammary infection. Milk yield and concentration of lactose and serum albumin (BSA) were significantly higher (P<0.001), and chloride ions significantly lower (P<0.001), in hind compared with fore quarters. Four cows developed clinical intramammary infection when subsequently challenged in the left hind quarter with Streptococcus uberis. For all parameters measured, i.e. protein, lactose, somatic cell count (SCC), BSA and immunoglobulins (IgG), milk from the infected quarter differed significantly from the uninfected quarters. No effect of infection was observed in quarters adjacent to the infected quarter, except for SCC, which increased significantly (P<0.001) in the uninfected hind quarter. Milk proteolytic activity in the infected quarter increased significantly (P<0.001) due to increased conversion of plasmin to plasminogen.

SJ, Lacy-Hulbert, MW Woolford, G Nicholas, and K Stelwagen

Proceedings of the New Zealand Society of Animal Production, Volume 56, , 65-67, 1996