König von Borstel, UtaWaiblinger, SusanneHaskell, MarieBarth, KerstinVogt, AninaAninaVogt2025-04-012025-04-012024https://jlupub.ub.uni-giessen.de/handle/jlupub/20426https://doi.org/10.22029/jlupub-19777Early separation of dairy cows and their calves shortly after birth is increasingly questioned by society, scientists and some farmers. Cow-calf contact (CCC) systems, which allow extended contact between a calf and their dam or a foster cow, are an alternative to this practice with many benefits for the animals’ welfare, but the weaning and separation process remains a major challenge in CCC systems. The aim of this thesis was therefore to compare the behavioral and physiological stress responses of dairy cows and their 3-months-old calves during weaning and separation either via two-step weaning using nose flaps (NF, 2 wks full-time contact while calves wore nose flaps, 1 wk fence-line contact before total separation) or via a gradual reduction of cow-calf contact time (GR, 1 wk half day contact, 1 wk morning contact, 1 wk fence-line contact before total separation, n=18 cow-calf pairs per method). As a secondary aim different indicators for weaning and separation stress were evaluated. The behavioural responses of 36 cow-cow pairs were directly observed in the cow area and via video monitoring in the calf area, which also included the selection gate where calves could switch between areas. Locomotor play levels and lying times of calves, as well as lying and rumination time of cows, were automatically recorded with sensors. Blood and fecal samples were collected for analysis of fecal cortisol metabolite concentrations, relative telomere length and immune responses. Milk yield was continuously recorded, and calves were weighed weekly. For the cows, no significant differences were found between the two separation methods in any of the used behavioral or physiological indicators. However, both methods led to an increase in vocalizations and searching behaviour compared to baseline at several time points, as well as to a transient increase in physiological stress markers, indicating that both methods provoked stress for the cows. For calves, the abrupt milk loss through the nose flap seemed to compromise adaptation of the gastrointestinal tract and led to low weight gains, reduced play behaviour and an increase in inflammatory blood markers. Furthermore, calves with nose flaps exhibited a marked decrease in lying and play behaviour, along with a high number of unsuccessful suckling attempts, which pointed towards a negative emotional state in NF calves. In contrast, GR calves showed higher weight gains, a lower decrease in lying bouts as well as a lower decrease in locomotor play levels during weaning compared to baseline, indicating a better adaption of the gastrointestinal tract to the dietary change as well as a likely less compromised affective state. In addition, the nose flap had caused pressure marks and injuries at the nasal septum of calves after the 14 days of usage. Results from our video analyses suggested that the calves needed to wear the nose flap for at least 4 days in order to effectively reduce suckling motivation, while there seems to be no benefit of using nose flaps longer than this time. However, it could not be determined whether nasal septum injuries were already present in our NF calves after the 4 days of usage. Given the overall beneficial effect of the gradual weaning and separation method for the calves and the missing difference in cows, the GR method seems overall favorable to reduce weaning and separation stress for cow-calf pairs compared to the NF method. Nonetheless, the GR method also caused considerable stress for the animals and recommendations for refinement are given in the thesis, highlighting, among others, the need to truly reduce the milk intake of calves and to focus on loosing established routines rather than just contact time itself. With regard to the stress indicators, it became evident that a low frequency of vocalizations during weaning should not be taken as evidence of low stress levels of animals, if not backed by further indicators. Relative telomere length as sampled in the present thesis was not a valid indicator of cumulative separation stress, while calves’ fecal cortisol metabolite concentrations were found to be a generally valid stress indicator for (unweaned) dairy calves, but unsuitable for comparing pre- and post-weaning states. In conclusion, this thesis provides valuable new insights to improve the weaning and separation process in CCC systems, that directly support practical applications as well as future research on this topic.enAttribution 4.0 InternationalTierwohlRindAbsetzenStressKuhgebundene Aufzuchtddc:630