Social interactions in a dairy herd are essential to maintain the herd's structure. Disturbances in social relationships can be stressful and may impact both animal welfare and production. Pathological and physiological changes, biological variations, but also the social environment induced by surrounding cows can affect variation in the daily milk production. This study aims to investigate the social interplay between cows during milking by examining the milking order in a milking parlour and determining if the individuals a cow stands next to will affect its daily milk yield. Milking order data from 234 individuals was collected from a two-sided herringbone parlour twice a day for 35 days. The indirect effect of the neighbour cows in the milking parlour was studied by fitting a linear mixed model to the daily milk yield residuals. The estimated indirect effects on milk yield ranged from-1.07 kg to 0.85 kg. We described a weak negative correlation of-0.26 (SE: 0.09) between direct and indirect effect estimates. The average of the indirect effects of neighbouring cows differed between different lactation stages and regrouped cows changed to a more negative estimated indirect effect in their new group. Our results show individual variation in the average indirect effect on the milk yield of the neighbour, with some individuals having a positive effect on their group mates, while others have a more negative effect. Further investigation of these effects would be helpful in selecting the best individuals in a herd and optimising group composition and milking routines.

A common management practice of commercial dairy farms is grouping cows according to their nutritional needs. Having different lactation groups also implies the regrouping of animals during their lactation period. Real-time locating systems based on ultra-wideband devices provide information about the cow's position inside barns. This information can be used to infer time budgets and animal locations on a continuous basis. The present study aimed to evaluate the behavioural changes that could be induced in dairy cows when regrouping between lactation groups by using location data obtained from real-time locating systems technology. This study is based on observational data from a commercial dairy farm, where 12 regrouping events, each involving between 3 and 15 cows, were recorded without any experimental intervention. The analyses included six months of data from two lactation groups with around 100 cows in each group. The effects of regrouping on time budgets and home range were analysed by comparing changes in regrouped cows before and after the process, and by comparing regrouped cows with their matched controls. The results showed that regrouping had a slight impact on the feeding and resting times of dairy cows. In contrast, parity was associated with opposing effects on feeding and resting times. Furthermore, regrouped cows tended to cover a larger area of the barn. The extent to which regrouped cows increased their use of barn space was also affected by the number of cows regrouped simultaneously. Our analysis of location data from a commercial dairy herd provides new insights into the impact of regrouping events on cow behaviour and welfare in commercial settings.

Mastitis is the inflammation of mammary glands and (one of) the most costly diseases in dairy cattle herds in developed countries (Halasa et al., 2007). The majority of antibiotics in dairy herds are used in the context of treating intramammary infections, which are the major cause of bovine mastitis (DANMAP, 2022). Current bio-economic simulation models used in the context of mastitis control generally assume that mastitis occurrence and pathogen transmission is a homogeneous process that may either originate from the environment (environmental) or the milking process (cow-associated transmission; e.g. Gussmann et al., 2018). However, research has shown that these assumptions are often wrong and unrealistic, as presumably purely cow-associated pathogens can also have reservoirs in the environment, and those pathogens categorized as environmental can behave in a cowassociated pattern and be transmitted via the milking process (Jørgensen et al., 2016;Zadoks et al., 2003). In addition, exposure to pathogens may not be random but governed by social interactions within the herd and the milking order of the cows. These assumptions may substantially impact the assessment of the cost-effectiveness of mastitis prevention and control strategies. This points out the need for data to properly parametrize these tools for accurate and economic assessment of mastitis prevention and control, to ensure sustainable dairy production.The availability of technology to record social interactions between animals and the milking order of cows may allow parametrization of decision support tools more realistically, providing farmers with a valuable and accurate tool for decision support making. Precision livestock farming (PLF) opened a myriad of possibilities to monitor disease transmission patterns through cattle positioning systems, computer vision, and data collected via milking machines and robots. With a real-time location system (RTLS) , cows can be identified and tracked when being at a feeding trough (Ternman et al., 2019), alleys, or cubicles with high accuracy (Pastell and Frondelius, 2018;Tullo et al., 2016). Also, the order of cows entering the milking parlor can be monitored (Hansson and Woudstra, 2023).One of the main goals of the research program on cow social interaction and disease transmission (CSI:DT) was to develop tools for minimizing disease transmission within dairy farms based on knowledge gained from continuous monitoring of the milking order of cows and the investigation of transmission patterns of frequently occurring mastitis pathogens. We summarize our publications (Table 1) and experiences from this research program in two opinion papers and give advice for future research within the field. In this opinion paper, we summarize our findings with regard to mastitis pathogens transmission and reservoirs as well as the milking order of cows.The disease we focused on in this project was mastitis. While mastitis is one of the most important diseases in dairy cow herds (Ruegg, 2017) and the prevalence of intramammary infections is usually high, direct contacts between individual cows are likely not playing a large role in transmission of mastitis pathogens. Instead, the consecutive use of milking equipment and pre-milking by milkers are thought to play a role in cow-associated transmission of pathogens from infected to uninfected quarters. In addition, there is also a transmission of pathogens that seem to have their primary reservoirs in the environment. Also, the consecutive use of infrastructure (e.g. cubicles) might be related to new infections. As described before, the general assignment of one transmission behavior to a certain pathogen species can be misleading as the transmission behavior within a species can vary between herds (Jørgensen et al., 2016;Zadoks et al., 2003).Most existing models for spread of cow-associated pathogens assume homogeneous mixing of cows during milking (e.g. Gussmann et al. (2018)). They do however not take hierarchy and social networks between cows into account which can influence which cows would like to enter a milking parlor together. Furthermore, other factors, such as housing group changes, that would influence transmission in the milking parlor are also not usually considered, as these would further complicate the models. Thus, the question arises how well these models can describe disease dynamics in a herd. Gussmann et al. (2018), for example, showed that infection rate had to be greatly reduced from rates estimated from field studies when some of these factors were taken into consideration more rigorously (such as, e.g., cow-specific susceptibility and decisions). However, they still assumed homogeneous mixing. In this project, we developed a similar simulation model where cow-associated mastitis transmission happens in the milking parlor and infection events are linked to the milking order of cows (Gussmann et al., 2024). This builds on the theory that the risk of infection from an infected cow is highest for the cow that is milked right after in the same place in the milking parlor (i.e. with the same milk liners), and then decreasing for the next cow being milked in the same place and so on. After calibrating the model, we tested if there was a difference when cows were milked in a random order and when cows with a clinical case of mastitis were milked first, or last. Our results showed that in a 'normal' dairy herd (i.e. a herd without an acute mastitis problem) there appeared to be no real difference between these three scenarios.Within this project, we have, also, investigated what role a cow's parity and lactation stage, characteristics that are usually also associated with a cow's hierarchy and social interactions within a herd, have on the probability of a cow entering the milking parlor rather early or later during milking (Hansson and Woudstra, 2023). We found that both parity and lactation stage are associated with the order in which cows enter a milking parlor. Cows in early lactation or first parity cows entered the milking parlor earlier than herd mates in later lactation or higher parity. Parity and lactation stage are therefore associated with the risk of getting in contact with liners which were contaminated with cow-associated pathogens during milking by a previous cow and therefore probably also with the risk of getting infected with these pathogens. This influence of hierarchy and social interactions on the milking order means that the milking order is not really random, as it has been assumed in previous simulation models. It is conceivable that such a "structured randomness" could have an influence on the transmission dynamics of mastitis pathogens in dairy herds, particularly as parity and lactation stage are considered risk factors for intramammary infections. We therefore hypothesize that milking first-parity cows, which have a lower risk of being infected with contagious organisms, at the beginning of the milking process would reduce transmission of contagious pathogens during milking. This has, to our knowledge, not been tested yet in simulation models and should be explored in the future.Due to the high cost associated with strain typing, many studies investigating mastitis epidemiology of different pathogens focused on the species-level only. However, in order to study the actual transmission of pathogens, strain level studies are required to investigate if cows are actually infected with the same strain of a species and to distinguish ongoing from new infections. Within the present project we therefore used strain typing to investigate the transmission routes of different staphylococci and streptococci, namely Staph. aureus, Staph. epidermidis, Staph. haemloyticus, Strep. uberis andStrep. dysgalactiae (Woudstra et al., 2023a, 2023b). Most studies using strain comparisons, including our own, found that Staph. aureus seems to be largely transmitted contagiously from quarter to quarter. Other pathogens such as Strep. dysgalactiae and Strep. uberis however, behave differently from herd to herd (Leelahapongsathon et al., 2020;Wente et al., 2019;Wente and Krömker, 2020).In this project, a farm with around 200 lactating cows was visited ten times at 14-day intervals and individual quarter foremilk samples were collected at each of the ten visits from all lactating cows. We found few cases of new infections due to contagious pathogen strains making it hard to estimate accurate pathogen transmission parameters, e.g. the rate of transmission through consecutive contact with milking liners. To study the level of importance of the different fomites (e.g. liners, milkers' hands), a large number of new infections needs to be observed, meaning studies have to be conducted either in herds with high prevalences, or studies have to include a large number of animals. Herds with high prevalences cannot be expected to represent an average herd, while large studies are expensive, and it is hard to get funding for these. Similar limitations are valid when studying the importance of consecutive use of infrastructure (e.g. cubicles) for pathogen transmission. We could, for example, demonstrate that cows of different parities prefer different areas in the barn (Churakov et al., 2021). At least in theory, also milk leakage in the cubicles between milkings could lead to transmission of pathogens from udder to udder.Milking order, social interactions and area utilization can play a crucial role in the transmission of infectious diseases. The sequential use of different areas in the barn and the close proximity between certain individuals can facilitate the spread of organisms between animals. In fact, the likelihood of disease transmission between individuals can be computed as a function of contact intensity (de Freslon et al., 2019). In this regard, PLF information, such as RFID tags providing milking order information or UWB sensors providing social interaction and area utilization information, offer the opportunity to automatically monitor the social interactions and area utilization of dairy cows. The use of this information might contribute in the future to facilitating the adoption of preventive measures to minimize the spread of pathogens on dairy farms.In our study, the prevalence of mastitis pathogens was low, making it hard to estimate accurate parameters that could be used in models. Furthermore, the simulation model we developed showed that in situations, where mastitis was not a big problem in the herd, changes in the milking order did not have a large influence on pathogen transmission. However, with increasing prevalence and transmission, changing the milking order had an increased influence on pathogen spread (Gussmann et al., 2024). We therefore suggest that measures connected to social contacts (induced for instance by milking order) should be considered by farmers depending on the main transmission patterns of pathogens with significant impact on milk quantity and quality in the herd making preventive measures economically meaningful. We also recommend that strain typing to become more widely used in mastitis investigations in the future, as transmission patterns can in some cases not be concluded from a mere species identification.

Access to mechanical brushes enables grooming behaviour in dairy cows and has shown benefits for cow welfare, including improved cleanliness, comfort, stress reduction. Brush-use may also promote a positive emotional state. Reduced brush use has been associated with health issues, suggesting its potential for automated health monitoring. This study aimed at evaluating whether data generated by pose estimation could be used to assess brush use patterns in loose-housed dairy cows. It presents an approach for automatically identifying the body segment being brushed as an application of pose estimation. Data collection was carried out at the Swedish Livestock Research Centre in a loose housing system equipped with an automatic milking system and two mechanical rotating brushes. Recordings spanned 25:30 h and used three cameras, at different positions, monitoring a single mechanical brush placed in a passageway between cubicle rows. One human observer with access to recordings from all three synchronized cameras annotated the data-set on a second-by-second basis. The observer recorded: (1) the number of cows using the brush; (2) the anatomical segment being brushed; and (3) whether brushing resumed after a pause. The same video recordings were processed with object detection and pose estimation, which predicted the location of bounding boxes for cows and for the brush as well as corresponding keypoints. Using the brush and cow keypoint locations, we attempted to detect brushing by anatomical region. In a first stage, machine-learning models were trained to predict brushing state (independent of location) using keypoint distance to the brush, achieving an accuracy of 86.3 %. To mitigate the risk of error propagation, we relied on human annotations to segment the video to confirmed brushing bouts for analysis in the second stage. To identify the anatomical location of brushing, two methods were evaluated: (1) simply assigning the brushing location to the closest keypoint, achieving 73 % average accuracy across classes, and (2) projecting brush and anatomical keypoints onto a spline modelling the cow's backline, resulting in 87 % accuracy. Misclassifications were predominantly limited to adjacent body segments. Given that intra-observer reliability was 90 %, the spline-based method was deemed sufficiently reliable for research applications to accurately monitor the specific body segments being brushed.

Cattle develop preferential relationships with other individuals in the herd. These social interactions between individuals have a significant impact on both animal welfare and production. Given the relevance of social behaviour in dairy cattle, scientific studies have focused on understanding social interactions among cattle. These may also be influenced by individual area preferences, particularly when animals are housed in confined spaces. Therefore, investigating the relationship between individual area preferences and social interactions is essential for understanding social behaviour in dairy cattle. Real-time location systems provide the opportunity to monitor individual area preferences and social contacts at the same time. This study aims to assess the impact of dairy cows' area preferences on their daily social contacts and to determine the potential implications of overlooking individual area preferences in social behaviour studies. The individual position of the lactating cows was automatically collected once per second for two months on a Swedish commercial farm housing dairy cows inside a free-stall barn. The location data of 243 lactating cows was used to construct the social networks and to estimate the similarity of the area utilisation distributions between these individuals. The effect of utilisation distribution similarity in social networks was investigated by applying separable temporal exponential random graph mixed models. The role of different cow characteristics in the similarity of the utilisation distributions was assessed through a linear mixed model. Our analyses stressed the importance of similarity of area preference, parity, kindergarten effect, and filial relatedness in shaping daily social contacts in dairy cattle. The kindergarten effect refers to the effect on cow behaviour of being grouped together in the early stages of their lives. Similarity of area preference was influenced by the kindergarten effect and relatedness by pedigree, which favoured interactions between these individuals. The described approach allowed to disassociate the area preference from the social contacts between cows, providing more accurate results of the importance of the cow’s characteristics on their social behaviour.

Social interactions between cows play a fundamental role in the daily activities of dairy cattle. Real-time location systems provide on a continuous and automated basis information about the position of individual cows inside barns, offering a valuable opportunity to monitor dyadic social contacts. Understanding dyadic social interactions could be applied to enhance the stability of the social structure promoting animal welfare and to model disease transmission in dairy cattle. This study aimed to identify the effect of different cow characteristics on the likelihood of the formation and persistence of social contacts in dairy cattle. The individual position of the lactating cows was automatically collected once per second for 2 wk, using an ultra-wideband system on a Swedish commercial farm consisting of almost 200 dairy cows inside a freestall barn. Social networks were constructed using the position data of 149 cows with available information on all characteristics during the study period. Social contacts were considered as a binary variable indicating whether a cow pair was within 2.5 m of each other for at least 10 min per day. The role of cow characteristics in social networks was studied by applying separable temporal exponential random graph models. Our results revealed that cows of the same parity interacted more consistently, as well as those born within 7 d of each other or closely related by pedigree. The repeatability of the topological parameters indicated a consistent short-term stability of the individual animal roles within the social network structure. Additional research is required to elucidate the underlying mechanisms governing the long-term evolution of social contacts among dairy cattle and to investigate the relationship between these networks and the transmission of diseases in the dairy cattle population.

In dairy farm management, cows that have newly calved the first time are continuously introduced to the milking barn. This can be stressful and potentially negative for the welfare of first lactation cows as they need to learn milking routines, adjust to an unfamiliar environment, and make new social contacts at once. Previous studies following behaviours after introduction to new environments or social groups have seen that cows return to baseline behaviours within a few days, however these studies were short and did not investigate the longer-term effects on their behaviours. Real-time Location Systems can be used to follow the behaviours of dairy cows 24/7 to ensure that adequate rest and feeding time are being achieved for good well-being and production. This study aimed to use sensor data to determine whether a heifer’s daily time budget becomes more stable within the first 45 days after introduction to the milking herd. Using a real-time indoor positioning system, 30 heifers at two commercial free-stall dairy farms housing roughly 200 lactating cows each were monitored.Using the locational data of the cows, the proportion of the daily activity that was spent in the cubicles, feeding area, and alleys was determined for the first 45 days following introduction to the milking herd. The cows' daily behaviours after introduction differed among individuals, 7 developed a more stable daily cubicle occupancy over time, while 4 became more unstable over time after introduction, and the remaining 19 heifers did not show a clear pattern. At both farms cubicle occupancy was the lowest at days 1-5. The cubicle occupancy also decreased at days 21-25, while time in the alley increased. In conclusion, no clear general patterns were observed for when and if a newly introduced cow reaches stable behaviours within the first 45 days after being introduced to the herd.

In modern freestall barns where large groups of cows are housed together, the behavior displayed by herd mates can influence the welfare and production of other individuals. Therefore, understanding social interactions in groups of dairy cows is important to enhance herd management and optimize the outcomes of both animal health and welfare in the future. Many factors can affect the number of social contacts in a group. This study aimed to identify which characteristics of a cow are associated with the number of contacts it has with other group members in 2 different functional areas (feeding and resting area) to increase our understanding of the social behavior of dairy cows. Inside 2 herds housed in freestall barns with around 200 lactating cows each, cow positions were recorded with an ultra-wideband real-time location system collecting all cows' positions every second over 2 wk. Using the positioning data of the cows, we quantified the number of contacts between them, assuming that cows spending time in proximity to one another (within a distance of 2.5 m for at least 10 min per day) were interacting socially. We documented in which barn areas these interactions occurred and used linear mixed models to investigate if lactation stage, parity, breed, pregnancy status, estrus, udder health, and claw health affect the number of contacts. We found variation in the number of contacts a cow had between individuals in both functional areas. Cows in later lactation had more contacts in the feeding area than cows in early lactation. Furthermore, in one herd, higher parity cows had fewer contacts in the feeding area than first parity cows, and in the other herd, cows in third parity or higher had more contacts in the resting area. This study indicates that cow characteristics such as parity and days in milk are associated with the number of contacts a cow has daily to its herd mates and provides useful information for further research on social interactions of dairy cows.

Heat stress in dairy cows can cause an increase in body temperature and respiration rate, and a decreased feed intake leading to reduced production. Dairy cows are better at handling heat when they have access to shade. Therefore, this study aimed to determine the effects of providing shade to high-yielding dairy cattle during the summer in the Swedish climate. Twenty high-yielding Swedish Red dairy cows, held on pasture, were divided into two groups, one with access to shade (S) and one without (NS). Milk production was recorded daily and shade temperature and relative humidity were recorded at 10 min intervals at pasture. A major effect of heat stress was found in cows in early lactation in the NS group. In this group, a high mean temperature two days before and a high THI two days before affected the milk production negatively (p < 0.001), which was the same for the maximum temperature and maximum THI measured on the same day (p < 0.001). Increases in the mean temperature and THI two days before also affected milk production negatively (p < 0.05) for cows in early lactation in the S group, though to a lesser extent. This study suggests that dairy cows in early lactation benefit from access to shade during summer.

Position data from real-time indoor positioning systems are increasingly used for studying individual cow behavior and social behavior in dairy herds. However, missing data challenges achieving reliable continuous activity monitoring and behavior studies. This study investigates the pattern of missing data and alternative interpolation methods in ultra-wideband based real-time indoor positioning systems in a free-stall barn. We collected 3 months of position data from a Swedish farm with around 200 cows. Data sampled for 6 days from 69 cows were used in subsequent analyzes to determine the location and duration of missing data. Data from 20 cows with the most reliable tags were selected to compare the effects of four different interpolation methods (previous, linear interpolation, cubic spline data interpolation and modified Akima interpolation). By comparing the observed data with the interpolations of the simulated missing data, the mean error distance varied from around 55 cm, using the previously last observed position, to around 17 cm for modified Akima. Modified Akima interpolation has the lowest error distance for all investigated activities (rest, walking, standing, feeding). Larger error distances were found in areas where the cows walk and turn, such as the corner between feeding and cubicles. Modified Akima interpolation is expected to be useful in the subsequent analyses of data gathered using real-time indoor positioning systems.

Real-time indoor positioning using ultra-wideband devices provides an opportunity for modern dairy farms to monitor the behavior of individual cows; however, missing data from these devices hinders reliable continuous monitoring and analysis of animal movement and social behavior. The objective of this study was to examine the data quality, in terms of missing data, in one commercially available ultra-wideband-based real-time location system for dairy cows. The focus was on detecting major obstacles, or sections, inside open freestall barns that resulted in increased levels of missing data. The study was conducted on 2 dairy farms with an existing commercial real-time location system. Position data were recorded for 6 full days from 69 cows on farm 1 and from 59 cows on farm 2. These data were used in subsequent analyses to determine the locations within the dairy barns where position data were missing for individual cows. The proportions of missing data were found to be evenly distributed within the 2 barns after fitting a linear mixed model with spatial smoothing to logit-transformed proportions (mean = 18% vs. 4% missing data for farm 1 and farm 2, respectively), with the exception of larger proportions of missing data along one of the walls on both farms. On farm 1, the variation between individual tags was large (range: 9-49%) compared with farm 2 (range: 12-38%). This greater individual variation of proportions of missing data indicates a potential problem with the individual tag, such as a battery malfunction or tag placement issue. Further research is needed to guide researchers in identifying problems relating to data capture problems in real-time monitoring systems on dairy farms. This is especially important when undertaking detailed analyses of animal movement and social interactions between animals.

Modern dairy cattle farms are usually equipped with cubicle systems to provide cows with comfortable condi-tions for lying down and resting. Cows are free to choose any cubicle they want, but in reality, they do not distribute themselves uniformly throughout the barn. There are many factors that affect where a cow lies down, such as hierarchy of a cow, access to resources, cow traffic nearby, etc. In this study, we used real-time location system data from two commercial farms to examine patterns of cubicle occupancy in relation to parity and lactation stage. We summarized cubicle occupancy over several days and compared different areas of the barn. Our findings suggest that, in general, there was a higher occupancy of cubicles close to the feeding areas. High parity cows lay down more frequently in cubicles close to the milking area as opposed to first lactation cows that tend to occupy less busy areas of the barn. The overall conclusion is that cubicle occupancy is not uniform throughout the barn, and patterns related to parity and DIM are seen. This information can be important for future studies on spread of diseases and for management purposes.

The study investigated equine responses to novelty and handling, aiming to reveal whether horse–human relationships reflect criteria of an attachment bond. Twelve adult Standardbreds were subjected to a fear-eliciting test (novel objects presented close to two humans) and a handling test (being led passing novel objects) to study attachment-related behaviours and ease of handling. The tests were performed both before (pre-test) and after (post-test) horses had been trained by the same female handler (10 sessions of 15 min). Horses were assigned to three groups of four, each of which underwent different operant conditioning protocols: negative reinforcement (NR; pressure, release of lead, and whip tap signals) or combined NR with either positive reinforcement using food (PRf) or wither scratching (PRs). Results showed that neither familiarity of the person nor training method had a significant impact on the horses’ behavioural responses in the post-tests. However, horses showed decreased heart rates between pre- and post-tests, which may indicate habituation, an effect of training per se, or that the presence of the familiar trainer served to calm the horses during the challenging situations. There were large individual variations among the horses’ responses and further studies are needed to increase our understanding of horse–human relationships.

The importance of rest and sleep is well established; we know, for example, that lack of sleep impairs immune function in rats and increases pain sensitivity in humans. However, little is known about sleep in dairy cows, but a lack of rest and sleep is discussed as a possible welfare problem in cattle. A first step toward a better understanding of sleep in dairy cows is to quantify the time cows spend awake and asleep in different stages of lactation. Using electrophysiological recordings on 7 occasions in wk -2, 2, 7, 13, 22, 37, and 45 in relation to calving, we investigated changes in rapid eye movement (REM) sleep time as well as non-rapid eye movement (NREM) sleep, drowsing, awake, and rumination in 19 dairy cows of the Swedish Red breed kept in single pens with ad libitum access to feed and water. The recordings on wk -2 and 45 were conducted during the dry period, and all others during lactation. The PROC MIXED procedure in SAS (SAS Institute Inc., Cary, NC) was used to test for significant differences in REM, NREM, drowsing, awake, and rumination between the different stages of lactation cycle. Pairwise comparisons between all recording occasions showed that total REM sleep duration was shorter for cows in wk 2 relative to calving compared with wk -2, and the number of REM sleep bouts were fewer in wk 2 compared with wk -2. The REM sleep was recorded during both the day (0500-2100 h) and night (2100-0500 h), but predominantly performed at night compared with daytime, and the bout duration was longer during nighttime compared with daytime. A tendency was observed for time spent in NREM sleep to be shorter in wk 2 relative to calving compared with wk -2. The duration spent drowsing was shorter for cows in wk 2 and 13 relative to calving compared with wk -2. We found no effect of stage of lactation cycle on the duration of awake or ruminating. Our study is the first to assess sleep distribution during a lactation cycle, and our results show that stage of lactation is important to consider when moving forward with sleep investigations in dairy cows. The shortest REM sleep duration was found for cows 2 wk after calving and longest 2 wk before calving, and the difference was due a higher number of REM sleep bouts in the recording 2 wk before calving. The REM sleep and rumination predominantly occurred at night but were recorded during both day and night.

In many species, animals live in highly structured groups. In these groups, individual differences in the number and identity of social contacts (alters) of each ego define the social network structure of the animal group. The composition of groups can be disturbed by grouping animals according to age or production stage, which can in turn induce stress. We investigated whether the preference of two animals to stay together depends on the sociality of each individual (defined by the time it spends close to other animals) or on the composition of the group. We observed 158 dairy cows distributed in 6 pens during 17 weeks. The precise positions of the cows were monitored with positional loggers 24/7 in two groups with fixed independent populations and during the formation of new groups with varying population. In fixed groups, the sociality of a cow was maintained over the entire observation period, but this trait depended on the area contacts occurred (inside vs. outside the resting area). When introducing foreign individuals into social groups, the sociality of individual cows was maintained independently of the group; this sociality was therefore not necessarily influenced by the time spent in the group but by the social characteristics of individual cows. During the formation of new groups, newly introduced cows dynamically interacted with resident ones, forming a few strong short-lasting contacts between newcomers and resident cows. However, a few long-lasting interactions occurred between resident and newcomers and the whole network is weakened. Our study suggests that each cow has its own sociality independent of the group and tend to establish relations with specific partners when the population is fixed. In addition, when introducing cows into a group, the social network of the group is weakened, with absence of strong links between newcomers and resident cows and a decrease in the links between resident cows for at least 2 weeks.

In human sleep studies, the probability of discomfort from the electrodes and the change in environment usually results in first-night recordings being discarded. Sleep recordings from the first night in human subjects often differ in amount of REM (rapid eye movement) sleep and the overall sleep architecture. This study investigated whether recordings of sleep states in dairy cows also show a first-night effect. Non-invasive electrophysiological recordings were carried out on nine cows of the Swedish Red breed during three consecutive 24-hour periods (recording days 1-3). Overall, cows spent 12.9 ± 1.4 hours awake, 8.2 ± 1 hours ruminating, 57.2 ± 20.3 min drowsing, 44.1 ± 20.2 min in REM sleep and 64.3 ± 38.1 min in NREM (non-rapid eye movement) sleep (mean ± SD) and there were no significant differences between recording days in total duration for any of the sleep and awake states. However, the bouts of REM sleep and rumination were longer, and the awake bouts were shorter, at night time compared to daytime, regardless of recording day. The awake bouts also showed an interaction effect with longer bouts at daytime during day 1 compared to daytime on day 3. Data on sleep and awake states recorded in adult dairy cows during three consecutive 24-h periods showed great variation in sleep time between cows, but total time for each state was not significantly affected by recording day. Further and more detailed studies of how sleep architecture is affected by recording day is necessary to fully comprehend the first-night effect in dairy cows.

To validate the accuracy of 2 commercially available activity loggers in determining lying, standing, walking, and number of steps in dairy cows, 30 cows were fitted with the CowScout Leg (GEA Farm Technologies, Bönen, Germany) system and the IceTag (IceRobotics Ltd., Edinburgh, Scotland) system. The CowScout Leg logger reports standing and lying in 15-min periods, whereas the IceTag logger reports standing and lying every second. To make data comparable, the IceTag data were therefore also summarized over 15-min periods corresponding to the paired CowScout Leg sensor. These data from the 2 systems were then analyzed (more than 1,000 cow days in total). Video recordings of a total of 29.5 h were used for labeling the behaviors of the selected cows (n = 10) and these labels were used as a gold standard to determine the accuracy with which these 2 loggers can record behavioral states lying, standing, walking, and the behavioral event number of steps. A concordance correlation coefficient analysis showed that both the standing and lying durations obtained with the 2 systems were almost perfectly correlated with the video labeling (IceTag: ρc = 0.999 and 0.999, respectively; CowScout Leg: ρc = 0.995 and 0.996, respectively). However, both loggers performed poorly regarding number of steps (classified as an event; IceTag: ρc = 0.629; CowScout Leg: ρc = 0.678) and CowScout Leg did not detect walking (classified as a state) very accurately (ρc = 0.860). The IceTag system does not measure walking behavior. When comparing the 2 loggers, the correlation between them for standing and lying was substantial (ρc = 0.953 and ρc = 0.953, respectively). The number of steps poorly correlated between the 2 loggers (ρc = 0.593), which might be due to the CowScout Leg logger being attached to the front leg and the IceTag logger being attached to the hind leg. We conclude that both the IceTag and the CowScout Leg logger are able to record standing and lying almost perfectly, but the step counting by both loggers and the walking recording by the CowScout Leg logger are not very accurate.

This study aimed to investigate whether reducing the milk flow and increasing the milk portion size of a computer-controlled milk feeder would lead to less cross-sucking and fewer unrewarded feeder visits in dairy calves. Five groups, each with 9 or 10 calves (n = 48), were housed in pens with one milk feeder in each pen, and exposed to four milk-feeding treatments in a cross-over design with four periods of 1 week. All four treatments involved a daily allowance of 8 L of whole milk, with variation in the maximum portion size and the rate at which milk entered the teat of the milk feeder. The treatments were: 1) 1 L/Low flow (1 l portions at a flow of 300 ml/min); 2) 2 l/Low flow (2 l portions at a flow of 300 ml/min); 3) 1 l/High flow (1 l portions at a flow of 600 ml/min); 4) 2 l/High flow (2 l portions at a flow of 600 ml/min). When the calves were fed milk in 2 l portions, they had fewer rewarded visits (P < 0.001) than when they were fed 1 l portions. When the calves were fed the milk in 2 l portions with a low flow, they spent more time on rewarded visits during which they did not ingest the whole portion (P < 0.05) and had more (P < 0.001) and longer (P < 0.001) rewarded visits during which they ingested less than 0.5 l of the portion. The treatments had no effect on the occurrence of cross-sucking. A higher number of bull calves were subject to cross-sucking than heifer calves (P < 0.001), and in total they also received more cross-sucking events than heifer calves (P < 0.001). Heifer calves initiated a higher frequency of cross-sucking than bull calves (P < 0.001). We concluded that when calves are given milk in 2 l portions, a very low flow should be avoided, as this may reduce the calves’ milk intake. The finding that bull calves were subject to cross-sucking more often than heifers, while heifer calves initiated more cross-sucking than bulls warrants further studies on these gender effects.