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Which dairy calves are cross-sucked?
Applied Animal Behaviour Science 125 (2010) 91–95
Contents lists available at ScienceDirect
Applied Animal Behaviour Science journal homepage: www.elsevier.com/locate/applanim
Which dairy calves are cross-sucked? Helja Laukkanen a,b , Jeffrey Rushen a , Anne Marie de Passillé a,∗ a b
Pacific Agri-Food Research Centre, Agriculture and Agri-Food Canada, PO Box 1000, 6947 Highway 7, Agassiz, BC V0M 1A0, Canada The University of Edinburgh, Royal (Dick) School of Veterinary Studies & Scottish Agricultural College, Easter Bush Veterinary Centre, Roslin, EH25 9RG, UK
a r t i c l e
i n f o
Article history: Accepted 13 April 2010 Available online 6 May 2010 Keywords: Dairy calves Cross-sucking Feeding behaviour Abnormal behaviour
a b s t r a c t We examined which calves within a group were the recipients of cross-sucking, whether this was related to body weight or feeding behaviour, and whether cross-sucking served to displace calves from the feeders. Forty-five Holstein dairy calves housed in groups of nine and fed by computer-controlled feeders were used. Calves were fed either 6 L/d or 12 L/d of milk and gradually (over 9 d) weaned off milk either by d47 or d89. Cross-sucking was recorded continuously for 12 h/d on 2 d at approximately 37 d, 47 d, 79 d and 89 d of age. Data on feeding behaviour were collected automatically by the feeders. There were large differences between calves in the duration of time being cross-sucked. There was a moderate positive correlation across calves in the duration of being cross-sucked and the duration of cross-sucking another calf. The top quartile of calves that were cross-sucked accounted for 68% of the total duration of cross-sucking. These calves had significantly higher bodyweights and spent more time in the milk feeders than the lowest quartile at most ages, but no difference was found in the time spent in the starter feeders. The calves were most often cross-sucked in the sawdust-bedded area at d37 and d47 and in the feeder areas at d79 and d89, but only a minority of cross-sucking occurred while the calf was actually in a feeder. In 80% of the episodes of cross-sucking that occurred when the recipient was in a feeder, the receiver remained in the feeder. Cross-sucking rarely resulted in a calf being displaced from a feeder. We concluded that larger calves that spend more time in the feeders seem to be at a higher risk for being cross-sucked but that cross-sucking does not serve to displace animals from the feeders. Crown Copyright © 2010 Published by Elsevier B.V. All rights reserved.
1. Introduction Calves are highly motivated to suck and, when reared separately from their dam, often cross-suck their pen mates. The factors that influence the motivation of calves to cross-suck one another have been studied extensively (reviewed in Rushen et al., 2008) but little is known of the factors that affect which calves are cross-sucked. Intersucking among older cattle is directed primarily at certain individuals (Spinka, 1992), but we do not know if this
∗ Corresponding author. Tel.: +1 6047961732; fax: +1 6047960359. E-mail address: [email protected] (A.M. de Passillé).
is so for cross-sucking by younger calves. Cross-sucking is thought to lead to irritation or even wounding of the body parts being sucked. If cross-sucking is disproportionately concentrated on a few calves within the group, this will increase the likelihood of wounding. The aim of this study was to examine if some calves were cross-sucked more than others and, if so, to identify some of the factors underlying this. Much cross-sucking has been observed to occur around the feeders (Bokkers and Koene, 2001). We examined if the calves being the cross-sucked the most were those that spent most time in the feeders, if crosssucking was directed at the smaller calves in the group, and if cross-sucking resulted in displacements of the crosssucked calves from the feeders.
0168-1591/$ – see front matter. Crown Copyright © 2010 Published by Elsevier B.V. All rights reserved. doi:10.1016/j.applanim.2010.04.002
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H. Laukkanen et al. / Applied Animal Behaviour Science 125 (2010) 91–95
2. Methods The data were collected as a part of a larger project designed to look at the effects of milk allowance (6 L/d vs. 12 L/d) and weaning age (47 d vs. 89 d) on the growth and behaviour of dairy replacement heifers (de Passillé and Rushen, 2009). We used this data set because weaning was found to provoke considerable cross-sucking (e.g. de Passillé et al., 2010). Housing, management and experimental procedures met the requirements of the Canadian Council for Animal Care. 2.1. Animals, housing and management Forty-five female Holstein calves were housed from 5 d or 6 d of age in groups of nine in 7.08 m × 4.74 m pens, with a plastic-coated expanded-metal-floored area at the front of the pen where the feeders were located, and a larger sawdust-bedded concrete-floored area at the back. As the calves entered the treatment at different times, there was a range of ages present in each group. The average age difference between the youngest and the oldest calf within a group was 22.2 d and this ranged from 9 d to 32 d. The feeding area contained one computer-controlled milk feeder linked to a computer-controlled calf starter feeder (CF 1000 CS Combi® , DeLaval Inc., Tumba, Sweden), one computer-controlled hay feeder and one computercontrolled drinker (Insentec B.V., Marknesse, Holland). The milk feeder used warm, pasteurised waste milk. The starter feeders served commercial calf starter mix with 17.4% protein, 6.37% fibre and 4.38% fat content (Unifeed Ltd., Chilliwack, BC, Canada) and were set to dispense the starter in 20 g portions, at a maximum rate of 9 kg/d. Hay was available from the age of 47 d onwards on an ad libitum basis. The feeders and drinkers recognized calves by their RFID tags and measured intakes of milk, starter, hay and water during each visit. The feeders were connected to the computer system at the calf barn for data collection: KalbManager Version 1.1 and Win Institut V02.18.24 programs (Foerster-Technik GmbH., Engen, Germany) were used for the collection of the data from the milk and calf starter feeders, and the Insentec RIC-System IV TIRIS Identification Roughage/Water Version 11 UH7802 program (Insentec B.V., Marknesse, Holland) was used for collection of the data from the hay and water feeders. Weigh scales (Western Scale Smart1, WesternScale Inc., Port Coquitlam, BC, Canada) were installed immediately in front of the milk and water feeders. Additionally, the calves were weighed manually once a week. For purposes of another experiment, the calves had been assigned to three dietary and weaning treatments (A: 6 L/d of milk a day and weaned on d47, B: 12 L/d of milk and weaned at 47 d and C: 12 L/d of milk and weaned at d89, de Passillé and Rushen, 2009). The calves were allocated to different treatment groups balanced by birth weight and age. There were three calves on each treatment in each group. All calves were weaned gradually over 9 d, as this had previously been identified as the least stressful weaning method (Sweeney et al., 2010). Prior to the experiment beginning, the calves had been separated from their mothers within 7 h of birth, fed 4 L
of colostrum within 6 h of birth, and moved to sawdustbedded, individual pens (1.22 m × 2.44 m). During that period, they were fed 3 L of milk twice a day by bottle, at 08:00 h and 15:00 h.
2.2. Behavioural observations Three video cameras were attached to the ceiling of each pen so that the entire pen could be viewed and recorded using digital video recorders (Genetec Inc., SaintLaurent, QC, Canada). The videos were viewed using specialized software (Omnicast Archive Player, Genetec Inc., Saint-Laurent, QC, Canada), with the three cameras being watched simultaneously. Each calf was observed continuously for 12 h/d (occurring between 06:00 and 24:00) at three approximate ages: (1) d37: 10 d before weaning began for calves in treatments A and B; (2) d47: weaning completed for calves in treatments A and B; (3) d79: 10 d before weaning for treatment C, and (4) d89: weaning completed for treatment C. These ages were chosen to give a representative sample of the cross-sucking that occurred before weaning and the increased crosssucking that occurred when the calves were weaned (de Passillé et al., 2010). At each age, we observed the calves for 2 d. At d47 and d89, the calves were watched on the first day that weaning was completed and either 1 d or 2 d later. For d37 and d79, the observation days were chosen within a period of 6 d to maximise the number of calves that were watched on any given day for practical reasons. The duration, location and the identity of the calf being cross-sucked and the identity of the calf cross-sucking were recorded for each cross-sucking event that lasted more than 10 s. Cross-sucking was defined as when the muzzle of one calf was positioned under the belly of another calf, either from the side, or from behind and between the back legs. The mouth/muzzle reached far enough underneath the belly to the point where it would reach the teats or navel of the other calf. If the calf was cross-sucking from behind, its head was at least the length of the distance between the nose and the eyes from the teats or was entirely covered by the hind end of the calf. Each group of calves was watched by a single, trained observer. The location at the start of the event of the calf that was being cross-sucked was recorded as either in (1) the stall of the milk feeder, (2) the stall of the starter feeder, (3) the stall of the hay feeder, (4) the stall of the water bin or (5) in the feeder area but not in one of the stalls, or (6) in the sawdustbedded area. The outcome of each cross-sucking event at a feeder was classified as either: (1) no displacement: the calf that was being cross-sucked remained in the feeder during and for a minimum of 15 s after the bout of crosssucking, which ended with the cross-sucking calf moving away, (2) removal without displacement: the calf that was being cross-sucked left the feeder stall during the bout of cross-sucking and the calf that did the cross-sucking did not enter the feeder within 15 s of the exit and (3) displacement: the calf that was being cross-sucked left the feeder stall and the calf that cross-sucked entered the feeder stall within 15 s of the end of the bout.
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2.3. Data analysis The mean duration of being cross-sucked per day over the 2 sample days at each age was calculated for each calf. We also calculated the overall mean duration summed over the four ages. The distribution of cross-sucking data was skewed and could not be transformed to achieve normality, so nonparametric methods were used for all analysis using SAS 9.1 (SAS Institute Inc., Cary, NC, USA) and Minitab 15 (Minitab® Statistical Software, Minitab Inc., Pennsylvania, USA). Medians, inter-quartile ranges and maximum and minimum values were used throughout for describing the data. Treatment effects were tested using a Kruskal–Wallis test at each age. In order to compare and contrast the calves that differed the most in the duration of being crosssucked, we compared calves that were below the 25th percentile (bottom quartile) in the overall duration of time being cross-sucked with calves that were above the 75th percentile (top quartile) in the overall duration of being cross-sucked. At each age, we compared these two groups of calves for body weight, the duration of time spent in the milk feeder and the duration of time spent in starter feeder using the Wilcoxon rank sum test. The stability across ages in the duration of being cross-sucked was analysed by correlating the duration of being cross-sucked on the four ages using Spearman’s correlation. 3. Results The overall amount of cross-sucking activity was quite low but there were large differences between calves in the duration of time they were cross-sucked (mean duration summed over the four ages: minimum = 0 s; 25th percentile = 10.1 s; median = 16.3 s; 75th percentile = 44.7 s; maximum = 312.5 s). The distribution of time being crosssucked was highly skewed: the 25% of calves that were cross-sucked for the longest time accounted for 68% of the total duration of cross-sucking. We found a low, positive correlation between the mean duration of being crosssucked and the mean duration of cross-sucking (r = 0.39, n = 45, P = 0.008) (Fig. 1). At all ages, the differences between individual calves were much larger than the differences between treatment groups. The effects of the milk allowance and age at weaning were not significant except on d47 (P = 0.014), which was the first day that the calves in treatments A and B were fully weaned off milk. On that day, the calves in treatment C (i.e. fed 12 L/d of milk and weaned at 84 d) were cross-sucked for longer (median = 25.0 s, minimum = 0 s, maximum = 192.5 s) than those in treatment A (fed 6 L/d and weaned at 47 d) (median = 0 s, minimum = 0 s, maximum = 63 s). The calves in treatment B (fed 12 L/d and weaned at 47 d) (median = 0 s, minimum = 0 s, maximum = 106.5 s) were intermediate. There was some stability across ages in the duration of cross-sucking received by a calf. There was a low, positive correlation between the duration of cross-sucking received on d37 and d47 (r = 0.33, n = 45, P = 0.027) and a moderate, positive correlation between d79 and d89 (r = 0.51, n = 45, P < 0.001). The correlation between d47 and d79 was not significant (r = 0.15, n = 45, P = 0.33).
Fig. 1. Duration of time cross-sucking and time being cross-sucked for each individual calf. Each point represents the mean value averaged over the four ages for each calf.
The locations of the calf being cross-sucked at different ages are shown in Table 1. Over all ages, about half of the instances of cross-sucking occurred while the cross-sucked calf was in the feeder area. However, with age there was a shift from calves being cross-sucked most often in the sawdust-bedded area at d37 and d47, to receiving more cross-sucking in and around the feeders at d79 and d89. However, at all ages, only 20–35% of instances of crosssucking occurred while the cross-sucked calf was actually in a feeder stall. In 79.3% of cases where the calf that was cross-sucked was in a feeder stall, the response of the calf being crosssucked was to remain in the feeder stall. In 13% of the cases, the calf left the feeder stall during or at the end of the crosssucking but was not replaced by the calf that performed the cross-sucking. In some of these cases, the cross-sucking continued outside the stall, whereas in others, this terminated the bout. Displacements, where the cross-sucked calf was replaced in the feeder by the calf sucking it, occurred in only 7.8% of cases. Fig. 2 shows the body weights of calves in the top (4th) quartile and bottom (1st) quartile in terms of the duration of being cross-sucked. The calves in the highest quartile for the duration of cross-sucking received had higher bodyweights on d37 (W = 108, P = 0.017), d47 (W = 108, P = 0.017)
Table 1 The percent of all events of cross-sucking received at each age while the calf being cross-sucked was at various locations within the pen. Location
Sawdust-bedded rest area Area around feeders In starter feeder stall In milk feeder stall In hay feeder stall In water drinker stall Number of events
Age (days) 37
47
79
89
Total
67% 11% 7% 10% 3% 2% 61
63% 9% 4% 17% 7% 0% 46
39% 15% 16% 11% 16% 3% 115
49% 15% 21% 8% 6% 2% 100
51% 13% 14% 11% 9% 2% 322
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tiles of calves at any age in their occupancy of the starter feeders (P > 0.10). 4. Discussion
Fig. 2. Box plot of the body weight of calves in the top quartile (crosshatched box) and the bottom quartile (open box) for the duration of being cross-sucked at each age (n = 12 in each quartile). The lower and upper boundaries of the box show the 25th and 75th percentile, respectively, the horizontal line in the box shows the median value, the vertical lines above and below the box show maximum and minimum value and each individual circle shows an individual calf that is a likely outlier.
and d79 (W = 114, P = 0.04), but no significant difference was found at d89 (P > 0.10). Fig. 3 shows the duration of time spent in the milk feeder of calves in the top (4th) quartile and bottom (1st) quartile in terms of the duration of being cross-sucked. There was a tendency for the calves in the bottom quartile to spend more time in the milk feeder than the calves in the top quartile at d37 (W = 184, P = 0.053). In contrast, at d79 and d89 the calves in the top quartile spent significantly more time in the milk feeder than the bottom quartile calves (W = 112, P = 0.030 and W = 114, P = 0.040, respectively). At d47, no significant difference was found between the two quartiles. No significant difference was found between the two quar-
Fig. 3. Box plot of the daily duration of time spent in the milk feeder stall of calves in the top quartile (cross-hatched box) and the bottom quartile (open box) for the duration of being cross-sucked at each age (n = 12 in each quartile). The lower and upper boundaries of the box show the 25th and 75th percentile, respectively, the horizontal line in the box shows the median value, the vertical lines above and below the box show maximum and minimum value and each individual circle shows an individual calf that is a likely outlier.
Our results show that being cross-sucked is not equally likely for all calves in a group, and that the calves that are cross-sucked the most are slightly heavier, spend more time in the milk feeders and do slightly more cross-sucking than calves that are not as cross-sucked as much. Therefore, we found no evidence that cross-sucking serves to displace smaller calves from a feeder. The distribution of duration of time spent being crosssucked was highly skewed with the top quarter of the calves accounting for nearly 70% of the total duration of cross-sucking. We cannot yet conclude whether these differences reflected differences between calves in the “attractiveness” for being cross-sucked or whether this reflects the fact that they did not resist being cross-sucked. As we only recorded events longer than 10 s, it is possible that the calves with very few recorded incidents of receiving cross-sucking were subjected to cross-sucking attempts, but managed to resist them successfully. The calf motivated to cross-suck may have attempted to cross-suck a number of calves until finally finding one that accepted the act without immediate resistance. In support of this, Keil and Langhans (2001) found that only 24–28% of udder sucking attempts lasted long enough for actual sucking movements to occur due to resistance by the calf being sucked. We found moderate correlations between the duration of time cross-sucking and being cross-sucked. This observation is consistent with Keil and Langhans (2001) and Spinka (1992) who found a significant positive correlation between the frequency of udder sucking and being sucked in older heifers. An obvious explanation for this would be mutual cross-sucking. Mutual cross-sucking was frequently observed by Roth et al. (2009) and they suggested that being cross-sucked could directly stimulate the act of cross-sucking. Although we did not systematically record instances of mutual cross-sucking, we only occasionally saw two calves cross-sucking each other at the same time and only two pairs of calves were seen to do this repeatedly. Much cross-sucking occurs around the feeders (Bokkers and Koene, 2001) and we found some evidence that calves that spent most time in the milk feeders were cross-sucked the most. However, it was evident that many instances of being cross-sucked occurred when the calves were not in a feeder. With age, there was a shift towards receiving more cross-sucking in the feeder area, whereas when the calves were young, they were most often cross-sucked when standing on the sawdust-bedded rest area. Relatively little cross-sucking occurred while a calf was actually in a feeder stall. Bokkers and Koene (2001) observed much preputial sucking and manipulation shortly before and after feeding in veal calves housed in groups, with the calf in the feeder stall being the primary subject. They suggested that competition for feeders may intensify the cross-sucking problem. This is in agreement with Weber and Wechsler
H. Laukkanen et al. / Applied Animal Behaviour Science 125 (2010) 91–95
(2001) who reported that calves cross-sucked significantly less frequently during the first 15 min after drinking milk when the milk feeder was equipped with a gate that prevented displacements from the feeder. However, we found no evidence that cross-sucking functioned as a means of displacing calves from the feeders: when the calves were being cross-sucked in the stall, in 80% of the cases they remained in place and the bout was ended by the cross-sucking calf moving away rather than the calf being cross-sucked leaving the feeder. Even when the calf being cross-sucked did leave the feeder stall, in most cases the calf doing the cross-sucking did not enter. We found no evidence that smaller calves were the ones being cross-sucked. Indeed, we found that the large calves seemed to be more at risk for being cross-sucked; this means that it is unlikely the individual’s susceptibility for being cross-sucked is related to social dominance. This observation is in agreement with Lidfors (1993), who found a significant positive correlation between the body weight, weight gain and the frequency of receiving crosssucking in bucket-fed calves. We found little effect of milk allowance or time relative to weaning on the duration of being cross-sucked. On d47, the calves that were un-weaned and drinking 12 L/d of milk appeared to be cross-sucked for longer than the calves that had been weaned, but the differences between treatment groups were much smaller than the differences between individual calves. Since much of the cross-sucking in the group is directed towards a small number of individuals, these animals may be at risk of udder trauma and inflammation, even when the overall level of cross-sucking in the herd is low. Identifying the animals that are at increased risk for being sucked
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could help in controlling the problem and minimizing the negative consequences for the individual animal. Acknowledgements We thank Fernando Borderas, Diogo Stilwell, Sue Vickers, and Gosia Zdanowicz for their help, and the Natural Sciences and Engineering Research Council of Canada and Agriculture and Agri-Food Canada for financial support. The research reported here forms part of the M.Sc. thesis of Helja Laukkanen at the University of Edinburgh. References Bokkers, E.A.M., Koene, P., 2001. Activity, oral behaviour and slaughter data as welfare indicators in veal calves: a comparison of three housing systems. Appl. Anim. Behav. Sci. 75, 1–15. de Passillé, A.M., Rushen, J., 2009. Can the weaning stress of dairy calves be reduced by weaning later? In: Proceedings of the 43rd Congress of the International Society for Applied Ethology, Cairns, Australia, 6–10 July 2009. de Passillé, A.M., Sweeney, B., Rushen, J., 2010. Cross-sucking and gradual weaning of dairy calves. Appl. Anim. Behav. Sci. 124, 11–15. Keil, N.M., Langhans, W., 2001. The development of intersucking in dairy calves around weaning. Appl. Anim. Behav. Sci. 72, 295–308. Lidfors, L.M., 1993. Cross-sucking in group-housed dairy calves before and after weaning off milk. Appl. Anim. Behav. Sci. 38 (1), 15–24. Roth, B.A., Keil, N.M., Gygax, L., Hillmann, E., 2009. Temporal distribution of sucking behaviour in dairy calves and influence of energy balance. Appl. Anim. Behav. Sci. 119, 137–142. Rushen, J., de Passillé, A.M., von Keyserlingk, M., Weary, D.M., 2008. The Welfare of Cattle. Springer, Dordrecht, The Netherlands, p. 303. Spinka, M., 1992. Intersucking in dairy heifers during the first two years of their life. Behav. Process. 28, 41–50. Sweeney, B., Rushen, J., Weary, D.M., de Passille, A.M., 2010. Duration of weaning, starter intake and weight gain of dairy calves fed large amounts of milk. J. Dairy Sci. 93, 148–152. Weber, R., Wechsler, B., 2001. Reduction in cross-sucking in calves by the use of a modified automatic teat feeder. Appl. Anim. Behav. Sci. 72, 215–223.
Contents lists available at ScienceDirect
Applied Animal Behaviour Science journal homepage: www.elsevier.com/locate/applanim
Which dairy calves are cross-sucked? Helja Laukkanen a,b , Jeffrey Rushen a , Anne Marie de Passillé a,∗ a b
Pacific Agri-Food Research Centre, Agriculture and Agri-Food Canada, PO Box 1000, 6947 Highway 7, Agassiz, BC V0M 1A0, Canada The University of Edinburgh, Royal (Dick) School of Veterinary Studies & Scottish Agricultural College, Easter Bush Veterinary Centre, Roslin, EH25 9RG, UK
a r t i c l e
i n f o
Article history: Accepted 13 April 2010 Available online 6 May 2010 Keywords: Dairy calves Cross-sucking Feeding behaviour Abnormal behaviour
a b s t r a c t We examined which calves within a group were the recipients of cross-sucking, whether this was related to body weight or feeding behaviour, and whether cross-sucking served to displace calves from the feeders. Forty-five Holstein dairy calves housed in groups of nine and fed by computer-controlled feeders were used. Calves were fed either 6 L/d or 12 L/d of milk and gradually (over 9 d) weaned off milk either by d47 or d89. Cross-sucking was recorded continuously for 12 h/d on 2 d at approximately 37 d, 47 d, 79 d and 89 d of age. Data on feeding behaviour were collected automatically by the feeders. There were large differences between calves in the duration of time being cross-sucked. There was a moderate positive correlation across calves in the duration of being cross-sucked and the duration of cross-sucking another calf. The top quartile of calves that were cross-sucked accounted for 68% of the total duration of cross-sucking. These calves had significantly higher bodyweights and spent more time in the milk feeders than the lowest quartile at most ages, but no difference was found in the time spent in the starter feeders. The calves were most often cross-sucked in the sawdust-bedded area at d37 and d47 and in the feeder areas at d79 and d89, but only a minority of cross-sucking occurred while the calf was actually in a feeder. In 80% of the episodes of cross-sucking that occurred when the recipient was in a feeder, the receiver remained in the feeder. Cross-sucking rarely resulted in a calf being displaced from a feeder. We concluded that larger calves that spend more time in the feeders seem to be at a higher risk for being cross-sucked but that cross-sucking does not serve to displace animals from the feeders. Crown Copyright © 2010 Published by Elsevier B.V. All rights reserved.
1. Introduction Calves are highly motivated to suck and, when reared separately from their dam, often cross-suck their pen mates. The factors that influence the motivation of calves to cross-suck one another have been studied extensively (reviewed in Rushen et al., 2008) but little is known of the factors that affect which calves are cross-sucked. Intersucking among older cattle is directed primarily at certain individuals (Spinka, 1992), but we do not know if this
∗ Corresponding author. Tel.: +1 6047961732; fax: +1 6047960359. E-mail address: [email protected] (A.M. de Passillé).
is so for cross-sucking by younger calves. Cross-sucking is thought to lead to irritation or even wounding of the body parts being sucked. If cross-sucking is disproportionately concentrated on a few calves within the group, this will increase the likelihood of wounding. The aim of this study was to examine if some calves were cross-sucked more than others and, if so, to identify some of the factors underlying this. Much cross-sucking has been observed to occur around the feeders (Bokkers and Koene, 2001). We examined if the calves being the cross-sucked the most were those that spent most time in the feeders, if crosssucking was directed at the smaller calves in the group, and if cross-sucking resulted in displacements of the crosssucked calves from the feeders.
0168-1591/$ – see front matter. Crown Copyright © 2010 Published by Elsevier B.V. All rights reserved. doi:10.1016/j.applanim.2010.04.002
92
H. Laukkanen et al. / Applied Animal Behaviour Science 125 (2010) 91–95
2. Methods The data were collected as a part of a larger project designed to look at the effects of milk allowance (6 L/d vs. 12 L/d) and weaning age (47 d vs. 89 d) on the growth and behaviour of dairy replacement heifers (de Passillé and Rushen, 2009). We used this data set because weaning was found to provoke considerable cross-sucking (e.g. de Passillé et al., 2010). Housing, management and experimental procedures met the requirements of the Canadian Council for Animal Care. 2.1. Animals, housing and management Forty-five female Holstein calves were housed from 5 d or 6 d of age in groups of nine in 7.08 m × 4.74 m pens, with a plastic-coated expanded-metal-floored area at the front of the pen where the feeders were located, and a larger sawdust-bedded concrete-floored area at the back. As the calves entered the treatment at different times, there was a range of ages present in each group. The average age difference between the youngest and the oldest calf within a group was 22.2 d and this ranged from 9 d to 32 d. The feeding area contained one computer-controlled milk feeder linked to a computer-controlled calf starter feeder (CF 1000 CS Combi® , DeLaval Inc., Tumba, Sweden), one computer-controlled hay feeder and one computercontrolled drinker (Insentec B.V., Marknesse, Holland). The milk feeder used warm, pasteurised waste milk. The starter feeders served commercial calf starter mix with 17.4% protein, 6.37% fibre and 4.38% fat content (Unifeed Ltd., Chilliwack, BC, Canada) and were set to dispense the starter in 20 g portions, at a maximum rate of 9 kg/d. Hay was available from the age of 47 d onwards on an ad libitum basis. The feeders and drinkers recognized calves by their RFID tags and measured intakes of milk, starter, hay and water during each visit. The feeders were connected to the computer system at the calf barn for data collection: KalbManager Version 1.1 and Win Institut V02.18.24 programs (Foerster-Technik GmbH., Engen, Germany) were used for the collection of the data from the milk and calf starter feeders, and the Insentec RIC-System IV TIRIS Identification Roughage/Water Version 11 UH7802 program (Insentec B.V., Marknesse, Holland) was used for collection of the data from the hay and water feeders. Weigh scales (Western Scale Smart1, WesternScale Inc., Port Coquitlam, BC, Canada) were installed immediately in front of the milk and water feeders. Additionally, the calves were weighed manually once a week. For purposes of another experiment, the calves had been assigned to three dietary and weaning treatments (A: 6 L/d of milk a day and weaned on d47, B: 12 L/d of milk and weaned at 47 d and C: 12 L/d of milk and weaned at d89, de Passillé and Rushen, 2009). The calves were allocated to different treatment groups balanced by birth weight and age. There were three calves on each treatment in each group. All calves were weaned gradually over 9 d, as this had previously been identified as the least stressful weaning method (Sweeney et al., 2010). Prior to the experiment beginning, the calves had been separated from their mothers within 7 h of birth, fed 4 L
of colostrum within 6 h of birth, and moved to sawdustbedded, individual pens (1.22 m × 2.44 m). During that period, they were fed 3 L of milk twice a day by bottle, at 08:00 h and 15:00 h.
2.2. Behavioural observations Three video cameras were attached to the ceiling of each pen so that the entire pen could be viewed and recorded using digital video recorders (Genetec Inc., SaintLaurent, QC, Canada). The videos were viewed using specialized software (Omnicast Archive Player, Genetec Inc., Saint-Laurent, QC, Canada), with the three cameras being watched simultaneously. Each calf was observed continuously for 12 h/d (occurring between 06:00 and 24:00) at three approximate ages: (1) d37: 10 d before weaning began for calves in treatments A and B; (2) d47: weaning completed for calves in treatments A and B; (3) d79: 10 d before weaning for treatment C, and (4) d89: weaning completed for treatment C. These ages were chosen to give a representative sample of the cross-sucking that occurred before weaning and the increased crosssucking that occurred when the calves were weaned (de Passillé et al., 2010). At each age, we observed the calves for 2 d. At d47 and d89, the calves were watched on the first day that weaning was completed and either 1 d or 2 d later. For d37 and d79, the observation days were chosen within a period of 6 d to maximise the number of calves that were watched on any given day for practical reasons. The duration, location and the identity of the calf being cross-sucked and the identity of the calf cross-sucking were recorded for each cross-sucking event that lasted more than 10 s. Cross-sucking was defined as when the muzzle of one calf was positioned under the belly of another calf, either from the side, or from behind and between the back legs. The mouth/muzzle reached far enough underneath the belly to the point where it would reach the teats or navel of the other calf. If the calf was cross-sucking from behind, its head was at least the length of the distance between the nose and the eyes from the teats or was entirely covered by the hind end of the calf. Each group of calves was watched by a single, trained observer. The location at the start of the event of the calf that was being cross-sucked was recorded as either in (1) the stall of the milk feeder, (2) the stall of the starter feeder, (3) the stall of the hay feeder, (4) the stall of the water bin or (5) in the feeder area but not in one of the stalls, or (6) in the sawdustbedded area. The outcome of each cross-sucking event at a feeder was classified as either: (1) no displacement: the calf that was being cross-sucked remained in the feeder during and for a minimum of 15 s after the bout of crosssucking, which ended with the cross-sucking calf moving away, (2) removal without displacement: the calf that was being cross-sucked left the feeder stall during the bout of cross-sucking and the calf that did the cross-sucking did not enter the feeder within 15 s of the exit and (3) displacement: the calf that was being cross-sucked left the feeder stall and the calf that cross-sucked entered the feeder stall within 15 s of the end of the bout.
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2.3. Data analysis The mean duration of being cross-sucked per day over the 2 sample days at each age was calculated for each calf. We also calculated the overall mean duration summed over the four ages. The distribution of cross-sucking data was skewed and could not be transformed to achieve normality, so nonparametric methods were used for all analysis using SAS 9.1 (SAS Institute Inc., Cary, NC, USA) and Minitab 15 (Minitab® Statistical Software, Minitab Inc., Pennsylvania, USA). Medians, inter-quartile ranges and maximum and minimum values were used throughout for describing the data. Treatment effects were tested using a Kruskal–Wallis test at each age. In order to compare and contrast the calves that differed the most in the duration of being crosssucked, we compared calves that were below the 25th percentile (bottom quartile) in the overall duration of time being cross-sucked with calves that were above the 75th percentile (top quartile) in the overall duration of being cross-sucked. At each age, we compared these two groups of calves for body weight, the duration of time spent in the milk feeder and the duration of time spent in starter feeder using the Wilcoxon rank sum test. The stability across ages in the duration of being cross-sucked was analysed by correlating the duration of being cross-sucked on the four ages using Spearman’s correlation. 3. Results The overall amount of cross-sucking activity was quite low but there were large differences between calves in the duration of time they were cross-sucked (mean duration summed over the four ages: minimum = 0 s; 25th percentile = 10.1 s; median = 16.3 s; 75th percentile = 44.7 s; maximum = 312.5 s). The distribution of time being crosssucked was highly skewed: the 25% of calves that were cross-sucked for the longest time accounted for 68% of the total duration of cross-sucking. We found a low, positive correlation between the mean duration of being crosssucked and the mean duration of cross-sucking (r = 0.39, n = 45, P = 0.008) (Fig. 1). At all ages, the differences between individual calves were much larger than the differences between treatment groups. The effects of the milk allowance and age at weaning were not significant except on d47 (P = 0.014), which was the first day that the calves in treatments A and B were fully weaned off milk. On that day, the calves in treatment C (i.e. fed 12 L/d of milk and weaned at 84 d) were cross-sucked for longer (median = 25.0 s, minimum = 0 s, maximum = 192.5 s) than those in treatment A (fed 6 L/d and weaned at 47 d) (median = 0 s, minimum = 0 s, maximum = 63 s). The calves in treatment B (fed 12 L/d and weaned at 47 d) (median = 0 s, minimum = 0 s, maximum = 106.5 s) were intermediate. There was some stability across ages in the duration of cross-sucking received by a calf. There was a low, positive correlation between the duration of cross-sucking received on d37 and d47 (r = 0.33, n = 45, P = 0.027) and a moderate, positive correlation between d79 and d89 (r = 0.51, n = 45, P < 0.001). The correlation between d47 and d79 was not significant (r = 0.15, n = 45, P = 0.33).
Fig. 1. Duration of time cross-sucking and time being cross-sucked for each individual calf. Each point represents the mean value averaged over the four ages for each calf.
The locations of the calf being cross-sucked at different ages are shown in Table 1. Over all ages, about half of the instances of cross-sucking occurred while the cross-sucked calf was in the feeder area. However, with age there was a shift from calves being cross-sucked most often in the sawdust-bedded area at d37 and d47, to receiving more cross-sucking in and around the feeders at d79 and d89. However, at all ages, only 20–35% of instances of crosssucking occurred while the cross-sucked calf was actually in a feeder stall. In 79.3% of cases where the calf that was cross-sucked was in a feeder stall, the response of the calf being crosssucked was to remain in the feeder stall. In 13% of the cases, the calf left the feeder stall during or at the end of the crosssucking but was not replaced by the calf that performed the cross-sucking. In some of these cases, the cross-sucking continued outside the stall, whereas in others, this terminated the bout. Displacements, where the cross-sucked calf was replaced in the feeder by the calf sucking it, occurred in only 7.8% of cases. Fig. 2 shows the body weights of calves in the top (4th) quartile and bottom (1st) quartile in terms of the duration of being cross-sucked. The calves in the highest quartile for the duration of cross-sucking received had higher bodyweights on d37 (W = 108, P = 0.017), d47 (W = 108, P = 0.017)
Table 1 The percent of all events of cross-sucking received at each age while the calf being cross-sucked was at various locations within the pen. Location
Sawdust-bedded rest area Area around feeders In starter feeder stall In milk feeder stall In hay feeder stall In water drinker stall Number of events
Age (days) 37
47
79
89
Total
67% 11% 7% 10% 3% 2% 61
63% 9% 4% 17% 7% 0% 46
39% 15% 16% 11% 16% 3% 115
49% 15% 21% 8% 6% 2% 100
51% 13% 14% 11% 9% 2% 322
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tiles of calves at any age in their occupancy of the starter feeders (P > 0.10). 4. Discussion
Fig. 2. Box plot of the body weight of calves in the top quartile (crosshatched box) and the bottom quartile (open box) for the duration of being cross-sucked at each age (n = 12 in each quartile). The lower and upper boundaries of the box show the 25th and 75th percentile, respectively, the horizontal line in the box shows the median value, the vertical lines above and below the box show maximum and minimum value and each individual circle shows an individual calf that is a likely outlier.
and d79 (W = 114, P = 0.04), but no significant difference was found at d89 (P > 0.10). Fig. 3 shows the duration of time spent in the milk feeder of calves in the top (4th) quartile and bottom (1st) quartile in terms of the duration of being cross-sucked. There was a tendency for the calves in the bottom quartile to spend more time in the milk feeder than the calves in the top quartile at d37 (W = 184, P = 0.053). In contrast, at d79 and d89 the calves in the top quartile spent significantly more time in the milk feeder than the bottom quartile calves (W = 112, P = 0.030 and W = 114, P = 0.040, respectively). At d47, no significant difference was found between the two quartiles. No significant difference was found between the two quar-
Fig. 3. Box plot of the daily duration of time spent in the milk feeder stall of calves in the top quartile (cross-hatched box) and the bottom quartile (open box) for the duration of being cross-sucked at each age (n = 12 in each quartile). The lower and upper boundaries of the box show the 25th and 75th percentile, respectively, the horizontal line in the box shows the median value, the vertical lines above and below the box show maximum and minimum value and each individual circle shows an individual calf that is a likely outlier.
Our results show that being cross-sucked is not equally likely for all calves in a group, and that the calves that are cross-sucked the most are slightly heavier, spend more time in the milk feeders and do slightly more cross-sucking than calves that are not as cross-sucked as much. Therefore, we found no evidence that cross-sucking serves to displace smaller calves from a feeder. The distribution of duration of time spent being crosssucked was highly skewed with the top quarter of the calves accounting for nearly 70% of the total duration of cross-sucking. We cannot yet conclude whether these differences reflected differences between calves in the “attractiveness” for being cross-sucked or whether this reflects the fact that they did not resist being cross-sucked. As we only recorded events longer than 10 s, it is possible that the calves with very few recorded incidents of receiving cross-sucking were subjected to cross-sucking attempts, but managed to resist them successfully. The calf motivated to cross-suck may have attempted to cross-suck a number of calves until finally finding one that accepted the act without immediate resistance. In support of this, Keil and Langhans (2001) found that only 24–28% of udder sucking attempts lasted long enough for actual sucking movements to occur due to resistance by the calf being sucked. We found moderate correlations between the duration of time cross-sucking and being cross-sucked. This observation is consistent with Keil and Langhans (2001) and Spinka (1992) who found a significant positive correlation between the frequency of udder sucking and being sucked in older heifers. An obvious explanation for this would be mutual cross-sucking. Mutual cross-sucking was frequently observed by Roth et al. (2009) and they suggested that being cross-sucked could directly stimulate the act of cross-sucking. Although we did not systematically record instances of mutual cross-sucking, we only occasionally saw two calves cross-sucking each other at the same time and only two pairs of calves were seen to do this repeatedly. Much cross-sucking occurs around the feeders (Bokkers and Koene, 2001) and we found some evidence that calves that spent most time in the milk feeders were cross-sucked the most. However, it was evident that many instances of being cross-sucked occurred when the calves were not in a feeder. With age, there was a shift towards receiving more cross-sucking in the feeder area, whereas when the calves were young, they were most often cross-sucked when standing on the sawdust-bedded rest area. Relatively little cross-sucking occurred while a calf was actually in a feeder stall. Bokkers and Koene (2001) observed much preputial sucking and manipulation shortly before and after feeding in veal calves housed in groups, with the calf in the feeder stall being the primary subject. They suggested that competition for feeders may intensify the cross-sucking problem. This is in agreement with Weber and Wechsler
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(2001) who reported that calves cross-sucked significantly less frequently during the first 15 min after drinking milk when the milk feeder was equipped with a gate that prevented displacements from the feeder. However, we found no evidence that cross-sucking functioned as a means of displacing calves from the feeders: when the calves were being cross-sucked in the stall, in 80% of the cases they remained in place and the bout was ended by the cross-sucking calf moving away rather than the calf being cross-sucked leaving the feeder. Even when the calf being cross-sucked did leave the feeder stall, in most cases the calf doing the cross-sucking did not enter. We found no evidence that smaller calves were the ones being cross-sucked. Indeed, we found that the large calves seemed to be more at risk for being cross-sucked; this means that it is unlikely the individual’s susceptibility for being cross-sucked is related to social dominance. This observation is in agreement with Lidfors (1993), who found a significant positive correlation between the body weight, weight gain and the frequency of receiving crosssucking in bucket-fed calves. We found little effect of milk allowance or time relative to weaning on the duration of being cross-sucked. On d47, the calves that were un-weaned and drinking 12 L/d of milk appeared to be cross-sucked for longer than the calves that had been weaned, but the differences between treatment groups were much smaller than the differences between individual calves. Since much of the cross-sucking in the group is directed towards a small number of individuals, these animals may be at risk of udder trauma and inflammation, even when the overall level of cross-sucking in the herd is low. Identifying the animals that are at increased risk for being sucked
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could help in controlling the problem and minimizing the negative consequences for the individual animal. Acknowledgements We thank Fernando Borderas, Diogo Stilwell, Sue Vickers, and Gosia Zdanowicz for their help, and the Natural Sciences and Engineering Research Council of Canada and Agriculture and Agri-Food Canada for financial support. The research reported here forms part of the M.Sc. thesis of Helja Laukkanen at the University of Edinburgh. References Bokkers, E.A.M., Koene, P., 2001. Activity, oral behaviour and slaughter data as welfare indicators in veal calves: a comparison of three housing systems. Appl. Anim. Behav. Sci. 75, 1–15. de Passillé, A.M., Rushen, J., 2009. Can the weaning stress of dairy calves be reduced by weaning later? In: Proceedings of the 43rd Congress of the International Society for Applied Ethology, Cairns, Australia, 6–10 July 2009. de Passillé, A.M., Sweeney, B., Rushen, J., 2010. Cross-sucking and gradual weaning of dairy calves. Appl. Anim. Behav. Sci. 124, 11–15. Keil, N.M., Langhans, W., 2001. The development of intersucking in dairy calves around weaning. Appl. Anim. Behav. Sci. 72, 295–308. Lidfors, L.M., 1993. Cross-sucking in group-housed dairy calves before and after weaning off milk. Appl. Anim. Behav. Sci. 38 (1), 15–24. Roth, B.A., Keil, N.M., Gygax, L., Hillmann, E., 2009. Temporal distribution of sucking behaviour in dairy calves and influence of energy balance. Appl. Anim. Behav. Sci. 119, 137–142. Rushen, J., de Passillé, A.M., von Keyserlingk, M., Weary, D.M., 2008. The Welfare of Cattle. Springer, Dordrecht, The Netherlands, p. 303. Spinka, M., 1992. Intersucking in dairy heifers during the first two years of their life. Behav. Process. 28, 41–50. Sweeney, B., Rushen, J., Weary, D.M., de Passille, A.M., 2010. Duration of weaning, starter intake and weight gain of dairy calves fed large amounts of milk. J. Dairy Sci. 93, 148–152. Weber, R., Wechsler, B., 2001. Reduction in cross-sucking in calves by the use of a modified automatic teat feeder. Appl. Anim. Behav. Sci. 72, 215–223.