The effects of heat stress on milk production and the grazing behavior of dairy Holstein cows milked by an automatic milking system

Abstract

The objective of the present study was to evaluate the productive performance and grazing behavior of 25 primiparous and 44 multiparous Holstein cows in a pasture-based automatic milking system (AMS) while experiencing heat stress (defined as a temperature-humidity index-THI ≥ 68). Productive traits were analyzed according to the THI from days 0, -1, -2, and -3 in relation to the milking day, and grazing behaviors (expressed as the % of daily observation time) were related to the average THI only on the day of observation. Milk yield was not associated with the THI on day 0, but a significant linear relationship was found with the THI on the three previous days, decreasing approximately 0.18 kg (primiparous) and 0.40 kg (multiparous) per THI unit increment. In contrast, for multiparous cows only, the milking frequency was positively associated with the THI on the day of evaluation but not on the previous days, increasing 0.01 milking/THI unit increments. Additionally, for each unit of THI increment, cows spent 0.14% more time standing, whereas they exhibited a decrease in grazing, lying, and ruminating behaviors time by 0.30%, 0.04%, and 0.70%, respectively, for both parities. In conclusion, milk loss was related to heat stress conditions from the previous days, but not milking frequency, which increased with the THI of the same milking day. Lower grazing, lying, and ruminating activities and greater standing behavior were observed due to heat stress.

Different Conditions during Confinement in Pasture-Based Systems and Feeding Systems Affect the Fatty Acid Profile in the Milk and Cheese of Holstein Dairy Cows

“…Contrary to our original hypothesis, we did not find any differences in the milk FAPs between both the mixed systems during the summer (ML2). Several studies have reported that heat stress in summer affects milk production, yield, and fat content, as well as milk fatty acid profiles [ 29 , 30 , 31 , 33 , 71 , 72 ]. Therefore, it was expected that, during summer, the OD-GRZ cows, being more exposed to the environment during confinement, would present a greater heat stress, resulting in a negative impact on their milk quality and FAs.…”

“…Cows can suffer from heat stress during spring–summer, which impacts their milk production and its quality. It has been reported that heat stress (a temperature humidity index (THI) above 68) negatively impacts their welfare [ 28 ], milk production, and its yield and fat content [ 29 , 30 , 31 , 32 ], as well as the milk’s FAP [ 33 ]. Salamon et al [ 34 ] showed higher percentages of C18:2, C18:3 (n-3), C18:1 (Oleic), and CLA in milk obtained during summer compared to those in milk from winter.…”

The Impacts of Heat Stress on Rumination, Drinking, and Locomotory Behavior, as Registered by Innovative Technologies, and Acid–Base Balance in Fresh Multiparous Dairy Cows

“…To our knowledge, little is known about the connection between HS and RWSregistered and acid-base balance biomarkers in fresh multiparous dairy cows [21][22][23][24]. Applying technologies like RumiWatch can provide dairy breeders with important information on how to reduce the negative effects of HS on cow health.…”