In this narrative review, the authors summarise the relationship between stress and behaviour and how dairy cattle cope with stressors. Based on the available literature, the most common stressors in intensive dairy cattle farming, such as pain, disease, heat stress, poor comfort caused by technology, and social stress, are surveyed. The authors describe how these stressors modify the behaviour of dairy cattle, influencing their feeding patterns, social interactions, and overall well-being. Additionally, the review explores the effectiveness of various coping mechanisms employed by dairy cattle to mitigate stress, including physiological adaptations and behavioural responses. This review is a valuable resource for understanding and grading stress in dairy cattle through behavioural reactions. Elucidating the intricate interplay between stressors and behaviour offers insights into potential interventions to improve animal welfare and productivity in dairy farming. Furthermore, this review highlights areas for future research, suggesting avenues for more comprehensive behavioural studies to enhance our understanding of stress management strategies in dairy cattle.

Bovine respiratory disease complex (BRDC) is a multifactorial disease in which, in addition to infectious agents and the individual resistance of animals, technological, management and climatic factors also play a role. Outdoor rearing in small groups has many advantages in terms of BRDC prevention. Continuous real-time monitoring of environmental factors, such as the temperature, relative humidity, air velocity, bioaerosols and harmful gases can also help to prevent damage by BRDC. Low temperatures in combination with elevated relative humidity and windspeed can lead to increased morbidity and mortality. Among noxious gases, ammonia may be of the greatest importance for respiratory diseases, as it directly damages the respiratory tract, leaving room and opening gate for pathogenic and opportunistic microbes. Bioaerosols of livestock buildings consist of feed, manure, organic matter from animals (e.g., epithelial cells, hair, urine, faeces), microorganisms, and toxins. Due to their size, particulate matter (PM) particles (PM10 and PM2.5) have important health effects, leading to severe respiratory and systemic diseases. Particulate matter formation and concentration depend on the housing and feeding conditions, species housed, stocking density, animal activity and environmental factors, but also on the sampling periods within a day. High temperature, low humidity, air movement (especially drafts), and increased activity of animals also cause the manure to dry, leading to dust formation and particles becoming airborne. With increased environmental control, the effects of the climatic factors on the calves health can be more easily identified, measures can be taken to reduce them, thus the occurrence and damage of possible diseases (mainly respiratory, BRDC) can be decreased.

The aims of the survey were to determine the prevalence of ketosis in dairy herds by measuring the concentration of beta‐hydroxybutyrate (BHBA) in milk by Keto‐Test (Sanwa Kagaku Kenkyusho, Nagoya, Japan); risk factors and the relationship with postpartum diseases were investigated. 1667 early lactating (days in milk 0–75) cows were tested in 52 dairy herds in 2013 and 2014 years. In total, 29.3 per cent of samples were positive (BHBA _MILK ≥100 µmol/l), including 3.7 per cent high positives (BHBA _MILK ≥500 µmol/l). The prevalence was similar in herds with less than or more than 9000 kg milk yield (0.34 and 0.38, respectively, P=0.4); however, it was higher in the herds with more than 1000 cows than in smaller herds (<500 and 500–1000 cows) (0.46, P=0.03). The BHBA level in milk was in a non‐linear positive relationship with parity (P=0.01), associated with retained placenta (P=0.0006), mastitis (P=0.02) and clinical ketosis (P<0.001). The results confirm the high prevalence of ketolactia in Hungarian dairy herds and its links to herd‐related and cow‐related risk factors and diseases occurring commonly in fresh cows.

The aim of this work was to determine the changes of redox indicators such as reactive oxygen metabolites (dROMs), plasma antioxidant test (PAT) and the oxidative stress index (OSI) in dairy cows at different stages of lactation using a diagnostic equipment which is suitable for in vivo oxidative stress (OS) monitoring procedures. In total, 628 dairy cows were examined in the pre-parturient period (days in milk [DIM]: -21 to -1 day; n = 117), in the calving and maternity period (DIM: 0 to 7; n = 137), in the early lactation period (DIM: 8 to 30; n = 139), and the in the peak lactation (DIM: 31 to 150; n = 235). The dROMs and OSI values were significantly different (P < 0.05) when comparing the 1st and 2nd+ lactation cows in each group. The highest mean value of dROMs was detected at the calving and maternity stage in 1st lactation cows (141 ± 25 U. Carr) and the lowest (103 ± 29 U. Carr) was found in peak lactation. The OSI developed similarly, with the highest value of 5.58 ± 0.94 in the calving and maternity period in the 1st lactation cows and the lowest value of 4.05 ± 1.21 in peak lactation and significant differences were found in many cases. Based on the results, the measurement of dROMs and OSI may be suitable for detecting oxidative stress in different lactation stages.

The profitability of cattle farming is largely determined by ensuring high-quality breeding animals for replacement and longevity in production. The provision of breeding animals requires adequate fertility of the cowherd and then intensive weight gain in the calf rearing period. For ensuring these demands, many management aspects must be considered. Continuous monitoring of the herd’s health status, including redox status, is essential. This review aims to provide a summary of relevant scientific data published in the last few decades regarding the role of oxidative stress (OS) in infertility of dairy cows and developmental diseases in calves, the major predisposing factors, and possible prevention.

Bovine respiratory disease complex (BRDC) is still one of the most challenging problems in calf rearing, therefore identification and continuous real-time monitoring of contributing environmental factors might play a role in mitigation of the damage caused by the disease. Microclimatic variables (temperature, relative humidity, air velocity, airborn particles expressed in particulate matter [PM], aerial germ load and gaseous pollutants) of a conventional calf barn and outdoor placed small-group hutches with pens were real-time monitored in a dairy herd by mounted sensors from summer to winter. Among the risk factors for BRDC, the small-group outdoor rearing units were characterized by high relative humidity, air velocity, and PM2.5 particulate matter concentration. Although the conventional calf barn was poorly ventilated, most variables were more favourable than expected, in which proper farm management may have played a role. We were able to identify long term and intraday periods with limit-breaking values, daily fluctuations as well as specific patterns of individual indicators in different calf husbandry environments. Based on obtained data, contributing technological processes may be reviewed and the effect of changes can be monitored under farm conditions. In addition, assessment of prevailing microclimatic conditions os also possible before investing in modernization of calf rearing units.