We aimed to compare the effect of individual versus pair housing on calves’ reaction to disbudding. We hypothesized that feeding, ruminating, resting, exploration, self-grooming and play would decrease after disbudding while pain-related behaviors (head rubbing, head shaking, foot stamping) would increase. Based on evidence of social buffering across species, we also hypothesized that pair-housed calves would feed, ruminate, rest, explore, groom, and play more but decrease occurrence of pain-related behaviors after disbudding. Lastly, we hypothesized that pair-housed calves would show more social resting and allo-grooming post- than pre-disbudding.
We found that head rubbing and head shaking significantly increased in all calves after disbudding while feeding increased only in pair-housed calves. Any other behaviors did not significantly change. Our results are similar to findings of some authors who studied effect of lidocaine used as the only pain mitigation in hot-iron disbudded calves. However, studies differ in the length of observational period as well as age of disbudded calves. Stilwell et al. (2012) found that 12 weeks old calves treated with lidocaine rubbed their head more 3 and 6 h post-disbudding than sham-disbudded calves6. Sutherland et al. (2018) found that 3 weeks old calves treated with lidocaine did not differ from sham disbudded in feeding of milk and lying time 24 h post-disbudding10. Mintline et al. (2013) found that 4.5 weeks old calves treated with lidocaine played less for 3 h post-disbudding than sham-disbudding calves8. Doherty et al. (2007) did not find any significant differences in grooming, feeding of concentrate and head rubbing (analysed on daily basis for 72 h post-disbudding) between 11 weeks old calves treated with lidocaine and sham-disbudded7. In general, our results on increased head rubbing and head shaking are consistent with findings of other studies which confirmed that both behaviors are reliable indicators of pain in disbudded calves6,26,29,31. Although foot stamping is also considered to be a validated pain-related behavior in disbudded calves32, our results do not support this notion.
To our knowledge there is no study addressing calves’ reaction to disbudding with respect to different housing conditions. The closest to our objective are studies Bolt et al. (2017), de Paula Vieira et al. (2010), Faerevik et al. (2007) and Gingerich et al. (2020). Bolt et al. (2017) and De Paula Vieira (2010) found improved ability to cope with weaning stress in pair-housed calves compared to individually housed individuals17,18. Faerevik et al. (2007) showed that calves vocalized less, were more active and explore more when tested with a companion calf in a separation test33. Gingerich et al. (2020) found that group-housed disbudded calves entered the shelter more frequently when it was not occupied and similarly left it more frequently when it was occupied. Authors explain their results by increased preference of disbudded calves for social withdrawal9.
We found that pair-housed calves increased feeding of hay (and straw but it was observed less frequently) compared to individually housed calves after disbudding which decreased the feeding. It is well known that animals including cattle decrease feeding after experiencing stress34–37. Therefore, it is possible that individually housed calves experienced higher levels of stress caused by disbudding and thus decreased feeding. Conversly, the presence of familiar social companion probably facilitated recovery from disbudding which resulted in increased feeding of hay in pair-housed calves. Despite the more frequent hay feeding, we did not find an increased rumination or concentrate intake in pair-housed calves. Non-significant changes in ruminating (despite the increased frequency of feeding), can show that it is not obvious whether the feeding frequency is connected to the amount of hay consumed or not.
There were either no significant differences between treatments in resting, play, exploration, self-grooming, and pain-related behaviors. The explanation might be that particularly these behaviors simply do not change between individually and pair-housed calves in relation to disbudding. In future studies we encourage researchers to focus on observation of those behaviors which were not included in our ethogram (e.g., standing). It could be also useful to assess calf behavior for a longer period than 24 h as calves experience ongoing pain for 3 weeks following disbudding4. For example, it would be interesting to see how long the change in feeding persists. Furthmermore, we suggest to use other methods to assess welfare of disbudded calves (e.g., cognitive judgement bias task38).
We did not find any significant differences in social resting, active and passive allo-grooming observed in PAIR calves pre- and post-disbudding. It is known that positive social interactions buffer against stress and thus we could expect they occur more frequently when animals experience stress. Our finding did not support this hypothesis. Furthermore, it seems to be to the contrast with results of Ede et al. (2020) who found that calves spent more time in proximity and paid more attention to a conspecific in pain compared to a sham treated calf. However, the authors also found that physical contact occurred infrequently among calves39. Gingerich et al. (2020) found that disbudded calves left shelter more frequently when it was occupied9 and Dunlap et al. (2020) found no evidence that fish affiliated more closely following tail amputation although social interactions mitigated the negative effects of the injury23. Taken together, further research is needed to investigate what quantity and which types of social interactions are effective for social buffering.
Further research should address effect of age and type of social bond on calf reaction to disbudding. Our calves were disbudded at age 58.84 ± 2.01 d (mean ± SD). Research on effect of social support in younger calves would be more applicable to farm practice because farmers prefer disbudding younger calves. For example, 63% of Czech farmers disbud calves before 4 weeks of age. The main reason may be that EU legislation allows the disbudding of calves without the use of pain-mitigating medication until 4 weeks of age2. Age may also affect the existence and/or strength of social buffering among paired calves as the social bonds develop gradually in young cattle40,41. If calves would be housed with dam, a much stronger social bond would be available for the calf than the bond to a peer in the case of pair-housing. Dam is the most preferred social partner during the first weeks of life, as she provides milk, active care and protection42,43. Therefore, it would be worthwile to assees social buffering of maternal presence on disbudded calves.
In conclusion, calves did not change resting, ruminating, play, exploration, self-grooming and foot stamping after disbudding. Pair and individually housed calves did not differ in how they changed resting, ruminating, play, exploration, self-grooming, and pain-related behaviors from pre- to post-disbudding. We found no evidence for increased social support among pair-housed calves in reaction to disbudding as the calves did not change their social resting or mutual allo-grooming behavior from pre- to post-disbudding. However, two pain-related behaviors (head rubbing and head shaking) increased after disbudding which supports a growing body of evidence that both, aneasthetic as well as non-sterodial anti-inflamantory drugs, should be administrated to calves. Feeding of hay increased in pair-housed calves after disbudding. Furthermore, it resulted in more feeding post-disbudding in pair-housed calves compared to individually housed animals. This finding is first evidence that socially housed calves react to disbudding differently than individually housed calves which may be the first indication of social buffering in disbudded dairy calves.