Changes in activity and milk components around onset of clinical mastitis
The objectives of the current study were to identify early indicators of naturally-occurring clinical mastitis in the first 30 DIM using peripartum daily activity, postpartum milk components, and milk yield data. A total of 200 cows that consisted of 136 Holstein (60 primiparous, 76 multiparous), 59 Jersey (24 primiparous, 35 multiparous), and 5 Crossbred (5 multiparous) animals were followed from January 2013 through September 2013. Daily activity was collected from 21 d prepartum to 30 d postpartum for all animals with a behavioral monitoring system (Afi PedometerPlus©, S.A.E. Afikim, Israel), which collected rest bouts, rest duration, rest time and step activity. Daily milk lactose % and fat:protein ratio were collected from 4 to 30 DIM for all animals, using an in-line milk analysis system (AfiLab©, S.A.E. Afikim, Israel) and daily yield was collected from the milk meter. Mastitis was defined as visual changes in milk appearance (flakes, chunks, or color) in one or more quarters as detected by the milk harvesters at the time of milking. Controls were defined as any animal in the same group, parity (1 or ≥ 2), and breed on the same date as the diseased cow, that did not experience any disease within the first 30 DIM. Differences between diseased and controls from d -7 to d 7 relative to disease, were examined using PROC GLIMMIX in SAS® (Cary, NC). Lactation number, day relative to disease, disease status, and their interactions were included in the model. Significance was determined at P ≤ 0.05. Animals that experienced mastitis (n = 15) showed more daily steps from d -5 to 0 and fewer daily rest bouts on d -1 and 0 relative to disease, compared to controls. Additionally, diseased cows showed reduced milk lactose % compared to controls from d -1 to 2 relative to disease and daily yield was decreased from d -2 to 1. Finally, no differences were found in daily rest time, rest duration or fat:protein ratio. This is the first study to show changes in activity and milk components prior to the onset of naturally-occurring clinical mastitis in early lactation. The identification of animals at risk for periparturient disease may allow producers to implement a proactive strategy for disease treatment, improve animal well-being and alleviate the economic losses associated with health problems during the transition period.
Keywords: mastitis, daily activity, milk components