Influence of milk components, somatic cells and supplemental zinc on milk processability

Individual milk samples from cows given different amounts of supplemental zinc were analysed for somatic cell count (SCC) and milk composition. The concentrations of immunoglobulins (IgA, IgG1, IgG2 and IgM), lactoferrin (LF), bovine serum albumin as well as total fat, total protein and lactose were analysed. The growth of starter cultures in milk samples was studied by the conductance technique used as a model for processability of milk. The concentrations of IgA, IgG2, IgM and LF as well as conductance measurements were found to be markers of processability in addition to SCC. Relatively low SCC in milk affected the growth of starter culture with a delayed start of the fermentation process up to 2-4 h. Supplemental zinc influenced the concentration of IgA, IgG2, IgM and LF while no effect on SCC was observed. The lag phase for growth of starter cultures was prolonged in milk from cows given additional zinc. (C) 2000 Elsevier Science Ltd. All rights reserved.