Beef-on-dairy and Holstein calves: Impacts of breed and pair composition on behavior and performance

Beef-on-dairy calves are present in dairy farms worldwide; however, little is known about their behavior or if social housing with purebred dairy calves may influence each other's behavioral patterns. The aim of this paper was to evaluate, through 2 studies, the effects of breed (Holstein vs. beef-on-dairy [Angus × Holstein] calves) and pair composition on performance, behavior, and behavioral responses in standardized tests. In Study 1 (n = 26 calves: 18 Holstein, 8 beef-on-dairy), we compared behavior and performance between the 2 breeds. Calves were observed by scan sampling (5 d/wk; after morning and afternoon milk meals; 14 scans/d per calf) using an ethogram including lying, self-grooming, exploration, idle, allogrooming, feeding, play, and abnormal oral behaviors. In Study 2 we compared breed and pair composition effects on behavior and performance. Calves were assigned (19 ± 2 d) to one of 3 possible pair composition: Holstein calves in homogeneous pairs (Holstein + Holstein; n = 13 pairs), mixed pairs (Holstein + beef-on-dairy; n = 11 pairs), and beef-on-dairy calves in homogeneous pairs (beef-on-dairy + beef-on-dairy; n = 7 pairs). Behavioral assessments were conducted weekly by scan sampling, twice a day, for 1h around milk meals (30 min before + 30 min after). Calves also underwent behavioral tests: food neophobia (2 times; 19 ± 2 and 48 ± 2 d), novel object (2 times; 16 ± 3 and 41 ± 2 d), unknown human test (65 ± 3 d). In Study 1, beef-on-dairy calves had greater body weight (BW) at weaning than Holstein calves. These calves also had more feeding, idle, and non-nutritive oral behavior scans, but fewer exploratory behavior scans compared with Holstein calves. Together, these results suggest that beef-on-dairy calves differ from Holstein calves in both growth and behavioral patterns during the preweaning period. In Study 2, Holstein calves showed more scans of exploration, whereas beef-on-dairy calves performed more abnormal oral behaviors (non-nutritive oral behaviors and cross-suckling), and feeding behaviors. In the food neophobia test, Holstein calves contacted less, took longer to contact, and consumed less novel food than beef-on-dairy calves. In contrast, in the novel object tests, Holstein calves were more likely to contact the object. Pair composition affected calf behavior, with more pronounced effects on Holstein calves when paired with Beef-on-dairy calves. When paired with beef-on-dairy, Holstein calves showed increased feeding behavior and abnormal oral behaviors and exhibited a longer latency to contact an unfamiliar human compared with homogeneous Holstein calves. BW did not differ between calves housed in mixed versus homogeneous pairs. However, within homogeneous pairs, beef-on-dairy calves were heavier than Holstein calves from approximately 70 d of age onward. Overall, Study 2 indicates that pair mixing influences the behavior of Holstein calves when housed with beef-on-dairy calves, but does not affect performance.