Glenda M. Pereira, Kirsten T. Sharpe and Bradley J. Heins, WROC, University of Minnesota
The excitement of releasing dairy animals to pasture every spring once the grass grows never gets old. At the West Central Outreach and Research Center in Morris, MN, all dairy animals other than calves born in the spring, are on pasture. As one of the few grazing and organic dairy research herds in the country, precision dairy technologies have been used to study behaviors of pasture-based dairy cattle and of course to help manage estrus, transition and health associated behaviors.
The technologies installed at the research herd, collect data continuously throughout the day, month and year. To retrieve the data so it can be used in real-time, solar powered routers may be utilized. Similarly, data can be collected twice a day once cows return to the milking parlor. The data can then be viewed on a computer system, on a website and some companies have applications for mobile devices.
Many precision technologies may accurately record feeding behavior; however, grazing behavior may be difficult to define because grazing may be considered both active and eating behavior because cows may graze while standing or while walking. Previous research has determined that most pasture-based dairy cattle graze for 8 to 10 hours per day and do so in bouts of 1.5 to 2 hours, and repeat that 4 to 5 times throughout the day. Once cattle go the pasture from the milking parlor, they tend to consume a large portion of their dry matter intake for the day. Typically, cattle will graze during the early morning and late afternoon, beginning at sunrise and ending around sunset. In the Midwest, fly pressure, humidity as well as the loss of moisture in certain forages (determining digestibility and palatability) can affect when cattle choose to graze. Even social hierarchy can determine when and how fast cattle tend to graze. Dominant cattle tend to graze on the best forages and for shorter amounts of times, having a larger bite rate, feeding faster than less dominant cattle.
Because many precision technologies do not monitor grazing behavior, grazing has not been researched as extensively. Recently in Ireland, a halter and pedometer system (RumiWatch, Itin and Hoch GmbH, Liestal, Switzerland) was validated for grazing behavior with 92% accuracy. The RumiWatch halter uses an oil-filled silicone tube with a built-in pressure sensor. The pressure difference caused by jaw movement generates a signal which is transmitted to a box on the side of the noseband and this data can be downloaded. Alternative grazing environments may provide opportunity for variation in monitoring behaviors.
The objective of the study was to validate a halter and pedometer for monitoring feeding and locomotive behaviors by direct visual observation in a grazing dairy herd in Minnesota, USA.
The study was conducted at the University of Minnesota West Central Research and Outreach Center organic dairy in Morris, Minnesota from May to June 2018. Lactating crossbred dairy cows (n = 12) were offered pasture for 22 hours per day and milked twice per day. The pastures were comprised of grasses and legumes that included smooth bromegrass, orchardgrass, meadow fescue, alfalfa, red clover, and kura clover. Cows were stocked at a rate of 3 cows per hectare and rotated to a new paddock every 2 days, with 4,834 kg of DM/ha available at the initiation of grazing.
The halter system can classify data as feeding behaviors, including ruminating, eating, drinking and other. In addition, the halter can classify jaw movements as grazing bites or rumination chews. The pedometer, a 3-axis accelerometer, monitors locomotive behaviors such as standing, lying and walking. Data from the halter and pedometer were collected in 10 Hz resolution, and the RumiWatch Converter V.0.7.3.36 transformed data into minute and hour summaries. Observational data were recorded by 3 trained observers on Samsung tablets, using the Pocket observer app (The Observer XT, Version 14.0, Noldus Information Technology, Leesburg, VA). Data from the visual observations were minutes and hour summaries.
Below is a summary (Figure 2), of daily time budgets, minutes per hour of the day that pasture-based dairy cattle grazed and ruminated. The organic research herd milks twice a day at 6:30 am and 4:30 pm, therefore cattle are brought up to the milking parlor and back to the pasture twice a day. As suspected, cattle tend to graze following the milking times, grazing for almost the full hour at 8:00 am and 8:00 pm (see Figure 2). Cattle don’t ruminate and graze at the same time, and therefore, the two are inverted. Interestingly enough, these cattle seem to graze throughout the entire day; however, summer temperatures may not have reached a consistently high temperature, and cattle may still feel comfortable grazing all day. During the nighttime, cattle tend to ruminate from 11:00 pm proceeding grazing and slowly decrease rumination time around 1:00 am where they spend time resting.
Because grazing is the main feeding behavior of pasture-based dairy cattle, temperature, forage mass and grazing ability, often influence their daily behaviors. The first experiment determined agreement between visual observation and the halter and pedometer. For this experiment, 144 hours of feeding and locomotive behaviors were evaluated. The second experiment evaluated correlation of grazing bites and rumination chews and 1,205 minutes were evaluated between visual observation and the halter system.
The results suggest the RumiWatchSystem may accurately monitor rumination and eating, as well as standing and lying behaviors. Behaviors such as drinking and walking were seldom observed and may be difficult to accurately monitor in grazing dairy cattle. More information about grazing dairy cattle and the use of halters and other technologies will be available in the near future.
This article is a compilation of the following two articles:
NODPA thanks Dr. Brad Heins and the researchers at the Department of DairyManagement, West Central Research and Outreach Center, University of Minnesota, for permission to re-print these two articles. Dr. Heins can be reached at 320-589-1711, Ext. 2118, or by email: hein0106@umn.edu.
