Margit Bak Jensen

Assessment of positive emotions in animals to improve their welfare

It is now widely accepted that good welfare is not simply the absence of negative experiences, but rather is primarily the presence of positive experiences such as pleasure. However scientific investigation of positive emotions has long been neglected. This paper addresses two main issues: first, it reviews the current state of scientific knowledge that supports the existence of positive affective states in animals and, second, it suggests possible applications of this knowledge that may enhance quality of life under animal management conditions. In the first part of the paper, recent advances in psychology and neuroscience are reviewed to provide pragmatic frameworks based on cognitive processes (such as positive anticipation, contrast and controllability) for further investigations of positive emotions in animals. Thereafter, the neurobiological bases of positive emotions are highlighted in order to identify behavioral and physiological expressions of positive experiences in animals. Monitoring both the autonomic nervous system (via heart rate and its variability) and the immune system could offer relevant tools to better assess emotional states in animals, complementary to classical adrenocortical measures. In the second part of the paper, useful strategies for enhancing positive experiences (such as physical, social and cognitive enrichment or putative genetic selection) are outlined. Then this paper emphasizes practical applications for assessing and promoting positive emotions that may help in providing animals with a better quality of life. Play, affiliative behaviors and some vocalizations appear to be the most promising convenient indicators for assessing positive experiences in laboratory and farm animals under commercial conditions.

Play behaviour in dairy calves kept in pens: the effect of social contact and space allowance

Abstract The effects of social contact and space allowance on the expression of play behaviour in domestic calves were studied. Forty-eight female dairy calves in three groups were housed in one of four pen types: (1) small single pen (0.9 m×1.5 m); (2) large single pen (1.8 m×3.0 m); (3) small group pen (1.8 m×3.0 m for 4 calves); and (4) large group pen (3.0 m×5.4 m for 4 calves). The behaviour of all calves was video-recorded for 8 h in week 2 and for 24 h in weeks 4 and 6 of the experiment. Data for play behaviour were obtained from each individual for all hours of observation. In weeks 4 and 6, space allowance affected the quantity of locomotor play. A low space allowance reduced locomotor play in both individually and group-reared calves. The quality of locomotor play was also affected. Elements of locomotor play that involve much movement were either absent or rarely seen in the small single pens. Furthermore, calves in single pens were less active than calves in group pens. The results of this study indicate that sufficient space is essential for the expression of play behaviour in domestic calves. It is suggested that play behaviour may be used to indicate the presence of good welfare in calves and in juveniles of other farm animal species. The use of a measure to indicate the presence of good welfare in addition to measures to indicate the absence of poor welfare may be a step towards a better assessment of welfare in farm animals.

Play behaviour in group-housed dairy calves, the effect of space allowance.

In dairy calves kept in pens, lack of sufficient space may inhibit the performance of play behaviour. The present study investigated, firstly, if an increase in space allowance increases the occurrence of play behaviour, and secondly, if calves kept at a low space allowance perform more locomotor play when released individually in a large novel area. A total of 96 dairy calves in six repetitions were housed in groups of four, in pens of either 4, 3, 2.2 or 1.5 m(2) per calf from 2 weeks of age. The occurrence of play behaviour in the home environment was recorded continuously for each individual calf during 24 h at 5, 7 and 9 weeks of age. Locomotor play decreased over the weeks (54, 29 and 19 s for weeks 5, 7 and 9, respectively; F(2,40)=17.98; P<0.001), and the interaction between space allowance and week tended to be significant (F(6,40)=1.96; P<0.10). At 5 weeks of age, calves kept at 4 or 3 m(2) per calf performed more locomotor play in the home environment than calves at 2.2 or 1.5 m(2) per calf (68, 74, 38 and 39 s for 4, 3, 2.2 and 1.5 m(2) per calf, respectively; F(3,15)=3.40; P<0.05), but in weeks 7 and 9, no effects of space allowance were found. In addition, the duration of locomotor play was recorded for all calves during an individual 10-min open-field test in a 9.6x4.8 m arena at 4 and 10 weeks of age. During the open-field test at 10 weeks of age, calves from pens with 1.5 m(2) per calf performed more locomotor play than calves on the remaining treatments (10, 9, 12 and 25 s for 4, 3, 2.2 and 1.5 m(2) per calf, respectively; F(3,15)=4.05; P<0.05). The present study shows that an increase in the available space increases the occurrence of locomotor play in the home environment at 5 weeks of age. It also shows that calves kept in pens with the smallest space allowance performed more locomotor play behaviour when released in a large arena at 10 weeks of age.

The effects of feeding method, milk allowance and social factors on milk feeding behaviour and cross-sucking in group housed dairy calves

Abstract Cross-sucking is non-nutritive sucking of another calf’s body. This detrimental behaviour is seen in artificially reared calves, but never in calves reared by the dam. The behaviour stems from a redirection of the natural sucking behaviour. Studies of calves fed milk in buckets have shown that cross-sucking may be reduced if teat buckets are used instead of open buckets. Prolonging the milk meal by reducing the milk flow rate and leaving the teat buckets available after the meal ensure the largest reduction of cross-sucking. These results are predominantly based on investigations with calves housed individually, in pairs or in groups of three. Prolonging the milk meal by reducing the milk flow rate in calves fed by computer-controlled milk feeders also reduced the occurrence of cross-sucking. Under commercial conditions there are often 20–40 calves per feeding station and much aggression around and displacement from the feeding station is seen. Furthermore, there is much cross-sucking around the feeding station. A gate may be fitted to the feeding station that protects the calf from displacement and prevents cross-sucking on the calf in the station. It is noted that both reduced milk flow rate and gating the feeding station may reduce the capacity of the feeder. Under standard conditions the calves pay several unrewarded visits to the computer-controlled milk feeder and restricted milk feeding has been found to increase the number of unrewarded visits. Cross-sucking may also be motivated by hunger and the influence of milk allowance, as well as distribution of milk meals, on use of the feeder and cross-sucking should be investigated. Furthermore, future research should focus on what an appropriate number of calves per feeding station is for computer-controlled milk feeders to function optimally and to ensure minimal problems due to aggression and cross-sucking.

Effect of single versus group housing and space allowance on responses of calves during open-field tests

Abstract 32 dairy heifer calves were housed in one of four pen types: (1) a small single pen (0.9 m × 1.5 m); (2) a large single pen (1.8 m × 3.0 m); (3) a small group-pen (1.8 m × 3.0 m for four calves); and (4) a large group-pen (3.0 m × 5.4 m for four calves) until three months of age. Thereafter, all calves were housed individually in tether stalls which were 0.9m wide. Each calf was subjected to two test-sessions: one before tethering at three months of age and one at six months of age. Each test session included two tests. The first test was an open-field test with an unfamiliar calf present and the second was an open-field test in an empty arena. Behaviour and heart rate were recorded. Based on the data for the open-field test with an unfamiliar calf present, two principal components reflecting exploratory motivation and fear of unfamiliar calves, respectively, were defined. At three months of age, individually reared calves had higher scores for the principal component reflecting fear of unfamiliar calves. Principal components reflecting exploratory motivation and fear, respectively, were also defined based on data for the open-field test in an empty arena. At three months of age, individually reared calves had higher scores for the principal component reflecting fear in this test. The results suggest that individually reared calves are more fearful when introduced to a novel social situation and when isolated in a novel arena. Differences in space allowance did not affect the measured responses during the tests at three months of age. At six months of age, no effects of either social rearing or space were found.

Technical note: Quantifying and characterizing behavior in dairy calves using the IceTag automatic recording device

The objectives of the current study were 1) to validate the IceTag (http://www.icerobotics.com) automatic recording device for measuring lying, standing, and moving behavior in dairy calves, and 2) to improve the information yield from this device by applying a filtering procedure allowing for the detection of lying versus upright. The IceTag device provides measures of intensity (I) of lying, standing, and activity measured as percent lying, percent standing, and percent active, but does not directly measure lying, standing, and moving behavior because body movements occurring while lying (e.g., shifts in lying position) and while upright (e.g., grooming) are recorded as activity. Therefore, the following 3-step procedure was applied. First, thresholds for I were determined by choosing the cutoff that maximized the sum of sensitivity (Se) and specificity (Sp). Second, a lying period criterion (LPC) was established empirically, and IceTag data were filtered according to the LPC, providing information on the posture of the animal as lying versus being upright. Third, a new threshold of I was estimated for moving activity conditional on the animal being upright. IceTag recordings from 9 calves were compared with video recordings during a 12-h period and analyzed using 2 x 2 contingency tables. Data from the first 4 calves were used to determine an LPC, whereas the remaining 5 calves served for validation of the procedure. An optimal LPC was found by modeling the deviance between IceTag and video recordings as a function of the LPC and choosing the LPC threshold that minimized the deviance. The IceTag device was found to accurately measure the high-prevalence behaviors (lying and standing; Se+Sp >1.90) and less accurately measure the low-prevalence behavior (moving; Se+Sp = 1.39). Application of the 3-step procedure using an optimal LPC estimate of 24.8 s resulted in an improved description of calf behavior, yielding a valid representation of the number and duration of lying and upright periods (Se+Sp = 2.00) within a precision of 0 to 49 s (95% confidence interval). In group-housed dairy calves, valid measures of the number and duration of lying and upright periods may be obtained from the IceTag device when applying the presented filtering procedure to the data. Measures regarding locomotion, on the other hand, should be used with caution.

Effects of confinement on rebounds of locomotor behaviour of calves and heifers, and the spatial preferences of calves

An open-field test and a preference test were used to investigate the motivation of calves and heifers to perform locomotor behaviour. Thirty-six calves and 48 heifers were housed in large pens for a pre-period of 2 weeks. During the last week of the pre-period, all calves were subjected to a 10-min open-field test where locomotor behaviours (walking, trotting, galloping and bucking) were recorded. The spatial preferences of 28 of the calves were also measured in a maze where they could choose between a large (21 m2) and a small (2.4 m2) goal room in six successive tests (runs). During the experimental period, calves and heifers were confined and thus deprived of the opportunity to perform locomotor behaviours for either 4 weeks, 2 weeks or 1 week immediately before being tested, or they stayed in the large pens for the whole period (control). All calves and heifers were subjected to the 10-min open-field test and 28 of the calves were subjected to the spatial preference test two days later. Finally, a third test was conducted in which 21 of the calves could choose between the large room and the small room containing a small amount of food. During the open-field test after the experimental period, confined calves galloped and bucked more than control calves (19.4, 17.1, 11.4 and 4.4 s for treatments 4wk, 2wk, 1wk and control; P<0.01), and more confined heifers were observed galloping or bucking (10/12, 6/12, 7/12 and 3/12 for treatments 4wk, 2wk, 1wk and control; P<0.05). These results suggest that confinement increases the motivation to perform locomotor behaviour. The calves showed a preference for the large room over the small room both before and after the experimental period, but there was no effect of treatment. The median latency to enter either of the two rooms increased over runs in the test before the experimental period (17, 22, 7, 48, 108, 63 s for runs 1, 2, 3, 4, 5 and 6; P<0.001) and in the test after the experimental period (17, 30, 41, 44, 84 and 64 s for runs 1, 2, 3, 4, 5 and 6; P<0.001). In the final preference test, the calves showed a clear preference for the small room containing food and the latency to choose was short and constant across runs (3 s). The results of the preference tests show that calves preferred to stay in a large room when given a choice, although this spatial preference may change in favour of food.

The effects of social contact and milk allowance on responses to handling, play, and social behavior in young dairy calves1

The aim of this study was to investigate the effects of social contact and milk allowance on social behavior, play behavior, and responses to handling in dairy calves. Forty test calves and 16 companion calves were allocated to 1 of 5 treatments from birth to 4 wk of age: (1) housed singly and fed 5 L of milk/d; (2) housed singly and fed 9 L of milk/d; (3) housed in pairs and fed 5 L of milk/d; (4) housed in pairs and fed 9 L of milk/d; or (5) kept with the dam and fed 9 L of milk/d. From 4 to 6 wk of age, all calves were offered 5 L of milk/d to promote intake of solid feed before weaning. At 6 wk of age, all calves were weaned, and at 7 wk of age, they were grouped (7 calves/group: 1 test calf from each treatment and 2 companion calves). The response to restraint during blood sampling was recorded weekly; singly housed calves struggled more during restraint than did calves kept with the dam, and pair-housed calves struggled at an intermediate level. Play behavior was recorded for 20 min/wk after the provision of fresh straw; calves housed singly and fed a low milk allowance spent less time playing than did calves in all other treatments. Three days after grouping, calves were subjected to a feed competition test; calves receiving the high milk allowance and housed in pairs spent more time feeding than did those receiving the high milk allowance and housed singly, with all other treatments showing intermediate responses. These results indicate that social contact decreased responses to restraint and increased play and competitive success. The high milk allowance increased play but reduced competitive success after grouping. Lower responses to restraint indicated less responsiveness to stress. Play is considered an indicator of positive welfare, and competitive success helps calves succeed in a group environment.

EFFECTS OF HOUSING IN DIFFERENT SOCIAL ENVIRONMENTS ON OPEN-FIELD AND SOCIAL RESPONSES OF FEMALE DAIRY CALVES

To investigate the effect of social contact during early development on open-field responses and social responses, 80 female dairy calves were housed either in open single pens (SOpen), closed single pens (SClosed), calf-groups (GCalf), or groups of calves and cows (GCow) until 3 months of age. During the first 3 months, the calves were open-field tested at 2 and 10 weeks of age. Calves isolated in closed single pens (SClosed) performed more exploration during the open-field tests at 2 and 10 weeks of age than did calves housed in open single pens (SOpen). During the open-field test after the experimental period at 6 months of age, previously isolated calves (SClosed) had a longer latency to enter an open-field arena, and during a social test at this stage group-reared calves (GCalf and GCow) sniffed and mounted other calves more than calves housed in single pens (SOpen and SClosed). The results suggest that isolation increases the motivation to explore a novel environment, and that housing in groups faci...

The effect of milk flow rate and milk allowance on feeding related behaviour in dairy calves fed by computer controlled milk feeders

The aim of this study was to investigate the effect of milk flow rate and milk allowance on calves’ use of a computer controlled milk feeder. Six blocks, each consisting of 16 calves, were used (Holstein–Friesian, Danish Red, and Jersey). Within each block, the calves were assigned to one of four treatments: low milk allowance and normal milk flow rate (LN), high milk allowance and normal milk flow rate (HN), low milk allowance and reduced milk flow rate (LR), or high milk allowance and reduced milk flow rate (HR). A low milk allowance consisted of 4.8 l of milk daily for the heavy breeds (Holstein–Friesian, Danish Red) and 2.8 l for Jersey, while high milk allowance were 8.0 l daily for the heavy breeds and 4.8 l for Jersey. The data collected automatically by the computer controlled milk feeder from day 15 until weaning showed that overall the combination of high milk allowance and reduced milk flow rate resulted in most time spent in the feeder during rewarded visits (P<0.01). However, there were significant breed effects. For calves of the heavy breeds a reduced milk flow rate resulted in a longer duration of rewarded visits (P<0.01) and in a longer duration of all visits (P<0.05). Also for calves of the heavy breeds, a high milk allowance resulted in fewer unrewarded visits (P<0.05), a shorter duration of unrewarded visits (P<0.01), and a shorter duration of all visits to the feeder (P<0.05). Furthermore, across breeds the reduced milk flow rate resulted in a longer duration of visits where the calves had access to milk but did not consume any (P<0.05). The behaviour of the calves was recorded for 24 h using video. These recordings showed that for the heavy breeds, the calves fed at a reduced milk flow rate occupied the feeder more than calves fed at a normal milk flow rate (P<0.05). The calves of the heavy breeds offered a high milk allowance entered a free feeder less often (P<0.05) and also entered the feeder less frequently as soon as it was free (P<0.05). Across breeds, the calves offered a low milk allowance in combination with a reduced milk flow rate tried more often to get access to an occupied feeder (P<0.05) and displaced other calves from the feeder more often (P<0.05). No effect of treatment was found on the occurrence of cross-sucking. The results show that for the heavy breeds, a reduced milk flow rate increased the mean occupancy of the feeder due to a longer duration of rewarded visits. Furthermore, for the heavy breeds a higher milk allowance reduced the mean occupancy through a reduction in the duration of unrewarded visits. These results support the hypothesis that a high number of unrewarded visits to computer controlled milk feeders may be due to hunger. They further suggest that the time the calves occupy the feeder may be reduced by a high milk allowance. The combination of a low milk allowance and a reduced milk flow rate may result in an increase in the competition for access to the feeder.