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Simple Summary: Johne's disease (JD) has detrimental effects on production and health and significantly reduces animal welfare. A recent study during peak lactation revealed that cows with JD (JD5) reduced their lying time compared to cows without JD (JD0). However, their step count was unaffected by JD, suggesting that the cows were standing idle, ruminating, or possibly standing eating. The objective of our study was to compare feeding behaviours and activity of JD5 cows to JD0 cows. The results support previous findings, with JD5 cows having lower lying times but no difference in step count. In addition, around week 8 of lactation, JD5 cows spent over 1 h/d longer ruminating, but there was no difference in eating times. Although it is still unclear what the cows were doing during these periods of reduced lying, this study does confirm behavioural difference between JD5 and JD0. Future research to further explore the difference in behaviour between JD5 and JD0 cows is recommended. Johne's disease (JD) significantly reduces the welfare of cattle worldwide. As changes in lying and feeding behaviours are considered important tools for assessing health and early detection of diseases, the aim of this study was to compare lying and feeding behaviours of JD-positive (JD5) and JD-negative (JD0) cows around peak lactation. The cows were fitted with an accelerometer-based sensor to record step counts and lying behaviour. They were also fitted with a pressure-based halter from approximately 56 d post-partum to collect feeding and rumination data. Every 3 months, the cows were milk sampled to test for naturally occurring JD using an ELISA. JD5 cows [n = 14 (two positive results in any four consecutive ELISAs)] were matched to JD0 cows [n = 14 (consecutive negative ELISAs)] based on lactation stage, parity, age, and milk yield. Of the 28 cows, 9 JD5 and 9 JD0 cows provided sensor data for analysis. JD5 cows spent 1.7 h/d less lying compared to JD0 cows. No differences in time spent eating were found; however, JD5 cows spent 1.1 h/d longer ruminating and produced 80 more feed boluses/d than JD0 cows around week 8 of lactation. The reason JD5 and JD0 cows behave differently around peak lactation is unclear and therefore warrants further investigation focusing on behaviour, milk yield, and feed intake among cows with JD. [ABSTRACT FROM AUTHOR]

The time spent lying down and ruminating are important behaviours that could be used for dairy cows' health assessment. This systematic review and meta-analysis investigated the alterations in lying time (LT) and rumination time (RT) and their effectiveness for the detection of subclinical ketosis (SCK), metritis, and hypocalcaemia in dairy cows during the periparturient period. Each disease was subjected to meta-analysis, with the LT and RT of healthy and diseased groups, measured before and after calving. Random effects were reported for 45 trials from 19 studies and the effect size was measured as the mean difference (MD). Heterogeneity and publication bias were evaluated using the I2 statistic, and Egger's test, respectively. Regarding SCK and metritis, the MD of LT was similar between the healthy and diseased groups in the pre-partum and post-partum (P > 0.05). Meanwhile, the MD of RT was significantly different in both periods (MD = −61.76 and −73.33 min/day, P < 0.05) for SCK and during the prepartum for metritis (MD = −23.37 min/day, P = 0.04). For hypocalcaemia, while LT only differed between the healthy and diseased cows in the post-partum, the MD of RT differed significantly between both groups in pre-partum (MD = −13.02 min/day, P < 0.001) and post-partum (MD = 21.53 min/day, P = 0.04) periods. Egger's test for publication biases was not significant for most outcomes of interest. Meta-regression depicted a lower predicted value for MD in the LT from pasture-based cows and RT from primiparous compared to free-stalls and primiparous cows, respectively. Our findings reflect that RT is a superior behavioural attribute to LT for the early detection of SCK and hypocalcaemia during the periparturient period. Systematic assessment of RT may assist farmers to identify and categorise cows into risk groups and interventions can be performed before the onset of clinical disease. • This study assesses the predictability of lying time (LT) and rumination time (RT) for transition diseases in dairy cows. • RT is superior to LT as an early predictor of subclinical ketosis and hypocalcaemia during the periparturient period. • The predictability of RT and LT is influenced by parity and housing design, respectively. • High heterogeneity exists between the studies. [ABSTRACT FROM AUTHOR]

Simple Summary: The effects of light exposure on dairy cattle milk production are well known, whereas aspects of light quality and potential benefits on dairy production and health are currently undetermined. We developed a supplemental lighting system (i.e., in addition to existing natural and artificial light in the facility) to provide light to cows while lying down. This study assessed dairy cow preferences for three colours of light-emitting diode lighting in the free-stall area. Cows did not prefer lying down under any of the light-emitting diode light options provided. Our results suggest that short-term use of supplemental light-emitting diode lighting in the stall area was not avoided by cows and lays the groundwork to study various aspects of light-emitting diode light, including the quality (wavelength), intensity, and duration of exposure. Light from the environment is important for vision and regulating various biological processes. Providing supplemental lighting in the stall area could allow for individually targeted or group-level control of light. This study aimed to determine whether dairy cattle had preferences for short-term exposure to white (full-spectrum) light-emitting diode (LED) light or no LED light, yellow-green or white LED light, and blue or white LED light in the stall area. In total, 14 lactating cows were housed in a free-stall pen with unrestricted access to 28 stalls. LED light was controlled separately for each side of the stall platform. Two combinations of light were tested per week, and each week consisted of three adaptation days and four treatment days. Lying behaviour and video data were recorded continuously using leg-mounted pedometers and cameras, respectively. Preference was assessed by the amount of time spent lying and the number of bouts under each light treatment. No differences occurred between treatments within each week for daily lying time and number of bouts. Similarly, no differences occurred between treatments within each time period. Further controlled studies of long-term exposure to different LED wavelengths and intensities are required to determine potential benefits on metabolic processes. [ABSTRACT FROM AUTHOR]

The aim of this study was to examine the time budgets of 20 lactating primiparous Italian Holstein cows and to determine the relationships between lying and standing behaviour, milk production and Body Condition Score in the first stage of lactation. Parturition period ranged from 15 September to 31 March and in the first seven lactation days all cows were equipped with individual 3-axes acceleration and angular displacement loggers, throughout 150 days for lying and standing behaviour measuring. Body Condition Scores (BCS) were estimated weekly, while milk production (in both morning and evening milking) and humidity and temperature air data were collected daily. Average individual milk yield was 27.3 ± 6.24 kg/d and milking time was 4.95 ± 1.94 min. Individual BCS was on average 3.46 ± 0.30 and standing daily time was 13.5 ± 2.26 h/d. Primiparous cows with BCS at parturition

The aim of this study was to examine the time budgets of 20 lactating primiparous Italian Holstein cows and to determine the relationships between lying and standing behaviour, milk production and Body Condition Score in the first stage of lactation. Parturition period ranged from 15 September to 31 March and in the first seven lactation days all cows were equipped with individual 3-axes acceleration and angular displacement loggers, throughout 150 days for lying and standing behaviour measuring. Body Condition Scores (BCS) were estimated weekly, while milk production (in both morning and evening milking) and humidity and temperature air data were collected daily. Average individual milk yield was 27.3 ± 6.24 kg/d and milking time was 4.95 ± 1.94 min. Individual BCS was on average 3.46 ± 0.30 and standing daily time was 13.5 ± 2.26 h/d. Primiparous cows with BCS at parturition <3.25 quite regained BCS after 20 weeks of lactation, but produced on average 2.3 kg/d (p <.001) less than the other cows. Primiparous cows with standing time <14 h/d in the first 21 days of lactation showed higher BCS than the others cows (+0.11 on average, p <.001), but did not produce more milk (+0.1 kg/d, p =.25) on average and showed smaller Linear Score (logarithm transformation of milk somatic cell count) than other cows. Primiparous cows with standing time <14 h/d had higher number of lying bouts and less minutes between two lying bouts, probably due to a higher cow activity to feeding. Multiple regression on milk production showed a low effect of standing time, but primiparous cows lost 0.34 kg/d (p <.05) for each standing hour. Primiparous cows with standing time <14 h/d in the first 21 days of lactation showed higher BCS than the others cows Primiparous cows with standing time <14 h/d showed smaller somatic cell count Primiparous cows lost 0.34 kg/d for each standing hour [ABSTRACT FROM AUTHOR]

Dairy cows in experimental grazing herds are often confined for metabolic measurements. The objective of this study was to establish effects of transfer from pasture, to tie-stalls in a metabolism house, then back to pasture, on lying behaviour and locomotion score of lactating cows: Holstein-Friesian (H, n = 16), Jersey (J, n = 16) and H × J (HJ, n = 16). Cows were transferred to tie-stalls on d 1 for 12 days, and were offered freshly cut ryegrass according to herbage allowance (HERB) and genotype: J low = 14; J high = 17; H and HJ low = 16; and H and HJ high = 20 kg DM/d. Lying behaviour was recorded on four days: −2, −1 (Pre-confinement), 3 (Early confinement), 10, 11 (Late confinement), 13 and 14 (Post-confinement) relative to transfer (d 1) using dataloggers, and was also video-recorded during the first 15 h. Locomotion score was recorded on days −4, −3, 12 and 16. No effects of HERB on lying variables were observed during the first 15 h in confinement, but J cows made more lying intentions (21.0 vs. 12.2; P < 0.05) and tended ( P = 0.07) to have a shorter latency to lie. Cows spent less ( P < 0.001) time lying in early confinement (07:22:29 h/d) than on any of the other occasions (9:12:50 h/d). Cows had more ( P < 0.001) and shorter ( P < 0.001) lying bouts in confinement than while at pasture. Low HERB cows spent more time lying than high HERB cows (09:54:55 vs. 09:09:33 h/d; P < 0.01). J had higher locomotion scores than H (9.2 ± 0.2 vs.7.8 ± 0.2; P < 0.001), and tended ( P = 0.09) to have higher scores than HJ (8.5 ± 0.2) cows. Locomotion scores were lowest pre confinement, highest at turnout (d 12), and intermediate after that at pasture (d 16) (7.6 ± 0.2, 9.3 ± 0.2 and 8.6 ± 0.3, respectively; P < 0.01). On transfer to the metabolism house cows showed disrupted patterns of lying although daily lying time returned to levels similar to pasture by late confinement. Confinement also resulted in a short-term deterioration in locomotory ability, which although improving, was still evident 4 days following the cows return to pasture with Jersey cows being more affected than the other genotypes. These findings suggest that longer adaptation periods and temporary release to loafing areas may improve both the validity of data collected and cow welfare. [ABSTRACT FROM AUTHOR]

Dairy cow welfare is an important consideration for optimal production in the dairy industry. Lameness affects the welfare of dairy herds by limiting productivity. Whilst the application of LS systems helps in identifying lame cows, the technique meets with certain constraints, ranging from the detection of mild gait changes to on-farm practical applications. Recent studies have shown that certain animal-based measures considered in welfare assessment, such as body condition, hock condition and leg hygiene, are associated with lameness in dairy cows. Furthermore, behavioural changes inherent in lame cows, especially the comfort in resting and lying down, have been shown to be vital indicators of cow welfare. Highlighting the relationship between lameness and these welfare indicators could assist in better understanding their role, either as risk factors or as consequences of lameness. Nevertheless, since the conditions predisposing a cow to lameness are multifaceted, it is vital to cite the factors that could influence the on-farm practical application of such welfare indicators in lameness studies. This review begins with the welfare consequences of lameness by comparing normal and abnormal gait as well as the use of LS system in detecting lame cows. Animal-based measures related to cow welfare and links with changes in locomotion as employed in lameness research are discussed. Finally, alterations in lying behaviour are also presented as indicators of lameness with the corresponding welfare implication in lame cows. [ABSTRACT FROM AUTHOR]

Lameness affects lying behaviour in dairy cattle, increasing total lying time and the number of lying bouts. However, there is limited information about the effect of lameness treatment on dairy cow behaviour. This study investigated the effect of four lameness treatments on lying behaviour (total lying time, number of bouts, average bout duration and laterality of lying) in dairy cows. Forty-four newly lame cows were treated randomly with one of four treatment protocols: trim only, trim + block, trim + NSAID, and trim + block + NSAID. Thirty-four non-lame control cows were matched by parity, days in milk, and farm-pen. Each cow had an accelerometer attached to the hind leg, lying behaviour data was collected over 5 days immediately after treatment and analysed using multilevel regression models. Lame cows in three of the four treatment groups demonstrated no increase in lying time compared to non-lame controls. This finding is contrary to previous work and may reflect the enrolment criteria which favoured the selection of cows with mild disease i.e. before the behavioural impacts of lameness had manifested. Only cows in the treatment group which received a therapeutic trim and a foot block saw higher lying times post treatment. As this effect was not apparent in the group which received a NSAID in addition to a trim and a foot block, we hypothesise that this effect is caused by discomfort associated with the block. Where foot blocks are administered as part of treatment protocols, we propose that NSAIDs should be administered concurrently to alleviate the behavioural changes and likely discomfort associated with this treatment. [ABSTRACT FROM AUTHOR]

Conventional dairy farming practices usually involve early separation of calves from their dams. Cow-calf contact (CCC) systems may offer an alternative rearing solution that allows for the expression of natural behaviours, such as suckling and bonding. However, literature exploring the effects of CCC systems on lying behaviours of lactating cows is limited. Thus, the aims of this study were to assess: (1) the lying behaviours of lactating dairy cows with and without access to a CCC area, and (2) freestall use and lying patterns of cows and calves with access to a CCC area over a 14-week suckling period. Cow-calf pairs (Swedish Holstein: n = 15; Swedish Red: n = 25) were assigned one of two treatments after calving: dam-calf contact rearing (full contact; FC, n = 19), where calves were housed in a CCC area in the same facility as their dams, or separation shortly after parturition (no contact; NC, n = 18). The CCC area contained stalls and concentrate feeders which only FC cows had access to. Daily lying time – as well as the duration and frequency of lying bouts – was collected for cows automatically using leg-mounted tri-axial accelerometers. Video recordings were also collected and used to perform scan sampling of cow and calf lying location at 10-minute intervals for a 24-hour period each week. Behavioural data was collected during 14 weeks, starting when all cow-calf pairs had entered the experimental pen and continuing until separation. Access to full CCC did not affect daily lying time nor the frequency of lying bouts. Overall, mean daily lying time increased with stage of lactation. Lying bout duration and frequency were affected by an interaction between stage of lactation and parity, with the frequency of lying bouts decreasing as lactation progressed, but only for primiparous cows in post-peak lactation. Average bout duration increased with stage of lactation for primiparous cows, and from early to post-peak lactation for multiparous cows. Moreover, there was an interactive effect of treatment and parity on lying bout duration, with multiparous FC cows performing longer bouts than primiparous FC cows. FC cows spent 77.3(28.4)% (mean(SD)) of their total lying time within the CCC area across all weeks. These results combined indicate that lying behaviour in this CCC system was likely influenced by factors other than CCC. Furthermore, cows with access to CCC maintained their individual patterns of stall use throughout the suckling period investigated in this study. • Daily lying time was not affected by cow-calf contact (CCC). • Cows with CCC spent over 75% of their daily lying time within the CCC area. • Lying patterns of cows with CCC did not change over a 14-week suckling period. • At any hour, calves occupied around six of the stalls intended for cow use. [ABSTRACT FROM AUTHOR]

Abstract: The aim of this study was to investigate behavioural changes before and after calving in dairy cows in order to describe behavioural signs of imminent calving and of cows’ recovery after calving. Thirty-two multiparous Danish Holstein Frisian cows with an unassisted calving were studied from 96h before until 96h after calving while housed in individual calving pens. Data on behaviour were obtained via video recordings and accelerometers attached to the cows’ legs. Cows spent less time lying, had more lying bouts and were more active the day before calving as compared to 2–4 days before calving. The number of lying bouts and the level of activity increased throughout the 6h prior to calving. During the last 2h prior to calving the duration of contractions and the number of times the cow turned her head towards the abdomen were increased, while the duration of feeding and drinking was decreased. Within minutes after calving cows stood up and licked their calves; second parity cows had a longer latency to stand than later parity cows. Sniffing and licking the calf peaked during the first hour after calving and decreased during the five successive hours, while calves’ sniffing the cow peaked during the second hour after birth. The high level of cows’ sniffing and licking their calves coincided with low levels of lying and feeding during the first hours after calving. Compared to the first 6-h period after calving, cows spent more time lying and feeding during the following two 6-h periods, while the duration of sniffing and licking calf and the number of lying bouts decreased throughout the 24h after calving. Calves spent the most time sniffing the cow and suckling during the first 6-h period after birth, while the time spent lying increased and the number of lying bouts decreased throughout the 24h following birth. Cows spent more time lying on the second day after calving than on the first day after calving. The results show marked behavioural changes during the last 6h prior to calving and suggest that behavioural changes may be useful indicators of imminent calving. Furthermore, the results show that the first hours after calving contain most cow–calf interaction. These behaviours were at the expense of the cows’ resting and feeding, which showed a rebound during the subsequent hours and the following day. This suggests that ample opportunity to rest and feed during the first days after calving may be beneficial for cow welfare. [Copyright &y& Elsevier]

Abstract: An animal expresses its physiological and well-being status by its behaviour. Changes in behaviour can be associated with health, production or well-being problems and therefore with the profitability of the farm. The objectives of the present study were to analyse lying patterns of healthy cows, collected with a commercial behaviour sensor, in early lactation in relation to environmental conditions, age of the cow and production performance. In future, these results may be used as a ‘baseline’ for detection of alterations in behaviour that indicate health problems. The study involved 210 healthy multiparous Israeli Holstein cows in three commercial dairy farms. Only healthy cows during the first 28 days after calving were included in this study. Data were analysed in relation to calving season, age of cows and correlation between milk production and lying time. The results show that lying time increased significantly with age and is significantly (P <0.05) higher in winter than in summer (summer lactation 2: 491±17min/day (mean±SD), summer lactation 3 and more: 520±25min/day, winter lactation 2: 531±25min/day, winter lactation 3 and more: 579±38min/day). The proportion of positively and negatively milk production and lying time correlated cows is affected by calving season. This study indicates that behaviour variables in early lactation are affected by calving season, lactation number and type of correlation between milk production and lying time. [Copyright &y& Elsevier]

Abstract: The factors influencing cows’ lying behaviour are not fully evaluated. Most studies dealing with lying behaviour were primarily aimed at comparing different designs for the resting area and floor surfaces, while only a few studies have investigated the cows’ preference of lying side. The aim of the present investigation was to test the hypothesis that cows choose equally between left and right lying-side. The study consisted of three experiments, where two were performed in a loose house system with automatic milking (AM) and only lactating cows participating, and the third was carried out on pasture. In the first and second study the herd consisted of 45–47 cows of the Swedish Red and White breed. The behaviour observations during the first study were made every 20min in 18 periods of 4h each. During the second study, cows were manually identified every 12min during 4 periods of 48h each. In the third study, observations were randomly performed during the day time for 59 days. In the study out on pasture at gestation month 9, the frequency of observations where cows were lying on the left side was significantly higher (p <0.012) than lying on the right side. In the two studies performed in the AM system the cows chose left and right laterality equally. No effect of age was seen on the choice of lying side. In the resting area, the cows lay with the ventral side against the activity area. [Copyright &y& Elsevier]

Abstract: The present experiment investigated the effect of reward duration on elasticity of the demand function for rest, and assessed for how long dairy heifers are motivated to lie on a 24-h basis. In Part 1, eight heifers housed in tether stalls had free access to lie down for 9h daily, while they could work for access to lie during 6-h daily test sessions. The price of access to lie down was varied by varying the fixed ratio of pressing a panel per reward (FR) from 10 to 50, and the reward duration was 20, 30, 50 or 80min. The reward duration affected the elasticity of the demand function. Based on the number of rewards earned, the elasticity of the demand function for 20-min rewards was more elastic (elasticity −0.33) than the demand functions for the longer reward duration periods (elasticity −0.07 to −0.08; P &#60; 0.001). Also based on the lying time during test sessions, the elasticity of demand function for 20-min rewards was more elastic (elasticity −0.32) than demand functions for the longer reward duration periods (elasticity −0.01 to −0.10; P &#60; 0.001). Heifers interrupted lying during the reward periods more often, the longer the reward duration (P &#60; 0.001). With a reward duration of 50min, heifers earned approx. 4h of lying in addition to the 9h where they were free to rest, i.e. they could lie down for a total of 13h. In Part 2, the same dairy heifers were free to rest for 6h and could work for access to lie during 12h daily. Reward duration was always 50min. Here heifers earned approx. 7h of lying during the test sessions (elasticity −0.07). During the 6h where the heifers were free to rest they lay down during on average 5.5h, i.e. total lying time was on average 12.5h. This suggests that heifers of this age and stage of pregnancy have an inelastic demand for rest of about 12–13h per 24h. [Copyright &y& Elsevier]

In some dairy cow grazing systems, during wet weather, the cows are removed from the pasture to a separate area for most of the day, in order to minimise treading damage to the soil. The objective of this study was to compare the effects of four surfaces commonly used for this “stand-off” procedure, in terms of cow lying behaviour, bodyweight, dirtiness, locomotion, and faecal concentrations of stress-induced hormones. In a replicated 4×4 Latin square design, 32 non-lactating Friesian cows were allocated in groups of four to either a specially constructed wood chip pad, a concrete yard, a gravel-surfaced farm laneway or a small paddock. The cows were held on the stand-off areas for 4 days, apart from a 3 h period each day spent grazing at pasture. Both the farm laneway and the small paddock became extremely muddy. The total time spent lying per day was greater (P<0.001) for cows on the wood chip pad (11.9 h), than for cows on the concrete yard (7.0 h), farm laneway (5.7 h), or small paddock (6.9 h). These effects were driven by differences in the frequency of lying down on the stand-off surfaces, as there were no treatment effects on mean lying bout duration during stand-off. Cows on stand-off treatments where lying was reduced attempted to compensate by lying down to a greater extent during the 3 h period at pasture. Cows on the concrete yard had lower bodyweights and higher faecal glucocorticoid metabolite concentrations at the end of the 4-day stand-off period than cows on the wood chip pad and the small paddock. Similarly, cows on the concrete yard had a reduced gait length at the end of the stand-off period compared with cows on the farm laneway and the small paddock. The cows on the wood chip pad were less dirty than cows on the other surfaces. These results highlight the importance of providing a well drained and comfortable surface for cows to rest upon during periodic weather-induced removal from the pasture. [Copyright &y& Elsevier]

• Lying behavior in healthy cows and those diagnosed with uterine diseases was compared. • Cows with retained placenta had longer lying times in the 3 weeks before calving. • Cows with metritis but without retained placenta did not change lying behavior. • Cows with retained placenta had increased markers of fat mobilization and inflammation. • Automatic measurement of behavior confirmed its potential as a disease predictor. The objective of this study was to assess how uterine disorders alter the lying behaviour and plasma biomarkers in dairy cows. 34 multiparous cows were retrospectively classified into three groups according to the first uterine disorder that cows were diagnosed with: retained placenta (RP), metritis (MET), or healthy (H; cows without any clinical disease). Lying time (LT) and duration of lying bouts (LB) were monitored between 6 weeks prior to and 8 weeks after calving via the AfiAct II pedometer. Blood samples were collected routinely between 14 days before and 28 days after calving. Data was analysed using Proc MIXED of SAS ver. 9.4. Regardless of grouping, both LT and LB were longer (P < 0.01) in the prepartum period (774 ± 16.6 min/day and 89.9 ± 2.1 min/bout) than in the first 28 days after calving (DFC; 653 ± 16.7 min/day and 63.7 ± 2.1 min/bout). Cows with RP had longer LT than healthy cows during the last 3 weeks before calving (837 ± 30.9 vs. 735 ± 27.1 min/day; P < 0.05). LT in cows with MET and healthy cows were not significantly different. The LB was similar among groups, averaging 76.1 ± 3.4 min/bout in healthy cows, 73.2 ± 3.8 min/bout in cows with RP, and 75.2 ± 3.7 min/bout in cows with MET (P > 0.05). Compared with healthy cows, cows with RP laid down longer and stood up for shorter times (P < 0.05), particularly before calving. In addition, cows with RP had increased mobilization of body stores and more pronounced inflammatory status, as demonstrated by plasma haptoglobin (P = 0.04) and albumin (P < 0.01) concentrations. Our data suggest that automatic monitoring of lying behaviour could help identify cows at increased risk of developing certain disorders, such as RP. [ABSTRACT FROM AUTHOR]

• Primiparous and multiparous cows are differently affected when introduced to a lactating group after calving. • Studies on behavioural effects of cow regrouping need to take parity into account. • Early but not recently familiar group mates contribute to behavioural synchronization. • Early-built relationships can persist in the long-term in dynamic dairy herds. As dairy cows' needs and demands change over the different phases of their reproductive cycle, regrouping is common practice in dairy farming to facilitate management and handling. However, social instability associated with regrouping is known to have negative effects on the cows, including disturbances in their lying behaviour. In this study, we examined the effect of familiar group mates on lying time and lying synchrony in a dynamic group of approximately 50 early lactating dairy cows during 23 regrouping events. We focussed on 13 primiparous and 33 multiparous post partum cows during 24 h after their introduction to the group as compared to a matched control sample of resident cows. We hypothesised that freshly introduced cows would lie shorter and behave less synchronously with the group as compared to resident cows. Further, we hypothesised that lying duration and lying synchrony will increase with the number of familiar animals present and that these effects may depend on whether the familiarity was acquired early in life or only recently. As predicted, primiparous fresh cows lied less and behaved less synchronous at the dyadic level than their matched residents. However, no such effect was present in multiparous cows. The presence of recently familiar animals had no influence on either primiparous or multiparous cows' behaviour. In contrast, early familiar animals affected the cows' behaviour in several aspects, yet differently in primiparas and multiparas. In fresh primiparas, an increasing number of early familiar animals present had a negative effect on lying duration. Among both fresh and resident primiparas, early familiar dyads were more synchronized than other pairs of animals. In multiparous cows, a higher number of early familiar cows present led to more synchronous behaviour with the group. We conclude that primiparous and multiparous cows are differently affected when introduced to a lactating group after calving. Duration and synchronization of lying behaviour indicated that primiparas are strongly challenged by their entrance to the group while multiparas cope well with it. In both primiparas and multiparas, lying behaviour was affected, albeit differently, by the presence of early familiar individuals, but not by recently familiar animals. The relations between familiarity, group dynamics, behavioural synchrony and lying behaviour are complex and need deeper investigation. [ABSTRACT FROM AUTHOR]