Abstract

A four-year study examined the effect of once a day (OAD) milking for complete lactations on mastitis and milk quality. The study comprised two herds of Jersey cows and two of Friesian cows, milked either OAD or twice a day (TAD) for a total of 4 lactations. Prevalence of intramammary infection (IMI) was determined by isolation of mastitis pathogens from quarter foremilk samples, collected aseptically at calving, mid lactation and at drying off. In the second and third years of the study, at drying off, cows milked OAD had three times as many (P < 0.01) quarters with IMI by major mastitis pathogens compared with TAD cows. Across all pathogens and years however, prevalence of IMI was not significantly or consistently higher for cows milked OAD compared with TAD. The somatic cell count (SCC) for uninfected cows milked OAD was approximately double that for TAD milked cows although this difference was only significant (P < 0.05) after the first 1-2 months of lactation had elapsed. Cows with minor or major pathogen infections also showed an approximate doubling of the SCC if milked OAD. Results suggest that milking OAD consistently increases the individual cow SCC but does not significantly increase prevalence of mastitis. KEYWORDS: once daily milking; mastitis; SCC; milk quality; milking frequency.

SJ, Lacy-Hulbert, DE Dalley, and DA Clark

Proceedings of the New Zealand Society of Animal Production, Volume 65, Christchurch, 137-142, 2005