Effects of partial cow-calf contact and social companions on health, performance, and behavior of young calves during cold season

Provision of cow-calf contact (CCC) in combination with pair housing may enhance welfare and stimulate greater intake of both milk and starter feed, thereby improving the performance and health of calves reared under cold conditions. This study was conducted to investigate the effects of combining partial daily CCC (5 h/d) with pair housing (19 h/d) in dairy calves reared in outdoor pens during winter, when the mean ambient temperature was 6.2°C throughout the study period. A total of 30 Holstein calves (birth weight = 37.4 ± 3.4 kg) were enrolled at birth. Fourteen calves received daily dam contact and were pair-housed (DC-PH), while the remaining 16 calves had no dam contact (NC); of these, 8 were pair-housed (NC-PH) and 8 were individually housed (NC-IH). Dam contact was maintained until day 60, after which all calves were weaned and group-housed until day 80. Milk consumption was greater in DC than NC calves (7.4 vs. 5.5 L/d). During the pre-weaning period, starter feed intake (d 0–30) was lower in DC vs. NC calves but not different from day 30–60. Pre-weaning average daily gain and feed efficiency (pre- and post-weaning) did not differ across treatment groups. However, DC-PH calves had superior post-weaning growth compared with NC calves. Rumen development was improved in DC vs. NC calves, as indicated by greater dry matter and NDF digestibility and protozoal counts. NDF digestibility was greater in NC-PH vs. NC-IH calves (87.7 vs. 81.4%). Pre-weaning blood glucose and post-weaning βHBA concentrations were greater, but pre-weaning cortisol was lower in DC calves compared with NC calves. Health challenges and antibiotic treatments were most frequent in DC-PH calves and least in NC-PH calves. During an 8-h behavioral recording prior to weaning, DC-PH calves spent less time devoting to non-nutritive oral activities such as licking the stall, fences, and sucking on other calves, and tended to spend more time in standing or contacting other calves, playing alone, walking, and ruminating. After weaning, DC-PH calves spent more time devoting to eating, resting, rumination, walking, and social interactions than NC calves, with no differences observed between NC-IH and NC-PH calves. In summary, partial daily dam contact (5 h/d), when combined with pair housing, resulted in superior post-weaning growth, improved rumen development, and positive behavioral expression but was associated with greater health risks under suboptimal winter conditions. Partial dam contact may represent a feasible compromise to enhance calf welfare while maintaining dairy productivity and addressing societal concerns regarding early cow-calf separation. However, disease risks should be mitigated through appropriate environmental management.