Review of the Heat Stress-Induced Responses in Dairy Cattle

Abstract

In the dairy cattle sector, the evaluation of the effects induced by heat stress is still one of the most impactful and investigated aspects as it is strongly connected to both sustainability of the production and animal welfare. On the other hand, more recently, the possibility of collecting a large dataset made available by the increasing technology diffusion is paving the way for the application of advanced numerical techniques based on machine learning or big data approaches. In this scenario, driven by rapid change, there could be the risk of dispersing the relevant information represented by the physiological animal component, which should maintain the central role in the development of numerical models and tools. In light of this, the present literature review aims to consolidate and synthesize existing research on the physiological consequences of heat stress in dairy cattle. The present review provides, in a single document, an overview, as complete as possible, of the heat stress-induced responses in dairy cattle with the intent of filling the existing research gap for extracting the veterinary knowledge present in the literature and make it available for future applications also in different research fields.

Behavioral Adaptations in Tropical Dairy Cows: Insights into Calving Day Predictions

“…Generalized linear mixed models (GLMMs) were carried out to perform both univariable and multivariable analyses. The GLMM was structured to explore the impact of lactation numbers (1, 2, and ≥3), days surrounding calving (−14 to 14), and the months of sensor measurement (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12) on activity patterns of dairy cows. The model accounts for the non-independence of repeated measurements taken from the same animals by incorporating random effects.…”

“…For univariable analyses, lactation numbers (1, 2, and ≥3), months of sensor attachment (1-12, indicating month of recording), and days surrounding calving (−14 to 14 days) were included as independent effects, while cow ID served as a random effect. Estimates of the least squares mean and their standard errors were derived from the predicted values of the univariable model for each lactation number (1, 2, and ≥3), for each month of sensor attachment (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12), and for days surrounding calving (from −14 to 14 days). The multivariable analyses included only statistically significant findings from the univariable analyses.…”

“…These analyses, tailored for each lactation number, evaluated predicted values including activity levels, total rest time, duration of rest per bout, and restlessness ratio. The evaluations took into account factors such as lactation numbers (1, 2, and ≥3), the period surrounding calving (−14 to 14 days), and the month of sensor attachment (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12). For assessing variance among lactation numbers during the calving period (−14 to 14 days), 29 distinct analyses of the predicted values were conducted.…”

“…Several studies on dairy cows’ behavior during the transition period (TP) in temperate and subtropical climates have been reported [ 6 , 7 ]. The unique climatic characteristics of the tropics, characterized by high ambient temperatures and humidity [ 8 ], substantially influence behavior and productivity [ 9 ]. For instance, heat stress often causes increased restlessness and altered eating patterns compared to cooler climates [ 10 ].…”

A CFD Methodology for the Modelling of Animal Thermal Welfare in Hybrid Ventilated Livestock Buildings

“…Animals tend to enhance heat dissipation by activating additional transfer mechanisms, for instance, panting or sweating [4]. Heat stress is remarkably critical for dairy cows as it correlates directly to a loss of milk yield [5,6] and relevant economical losses [7,8]. Since heat stress stems from the inability to dissipate an excess of metabolic heat, the productivity level of dairy cows is directly influenced by thermohygrometric conditions inside livestock buildings.…”