Abstract

Dairy farming in New Zealand has traditionally utilized a twice a day (TAD) milking system, but milking once a day (OAD) for the entire lactation is also practiced by a significant proportion of dairy farmers. This study reports on the differential gene expression in milk from OAD and TAD cows. Three predominant dairy breed group of New Zealand, Holstein-Friesian (F), Jersey (J) and F×J crossbred (F×J) were included in samples collected from both milking regimens. RNA was extracted from milk from 45 OAD and 42 TAD dairy cows during early lactation, and used to determine lactoferrin (LF) and insulin-like growth factor-1 (IGF-1) gene expression using qPCR. Compared to TAD cows, cows milked OAD had higher expression of the LF gene (1.38 vs 1.30 folds, P=0.08) and the IGF-1 gene (1.65 vs 1.48 folds, P=0.09). These results suggest that milking frequency affects the expression of milk composition genes at early lactation.

K, Gedye, S Notcovich, M CorreaLuna, P Ariyarathne, A Heiser, and N Lopez-villalobos

New Zealand Journal of Animal Science and Production, Volume 78, Lincoln, 109-110, 2018