Effects of twice a day teat bucket feeding compared to twice a day mother suckling on behaviour, health traits and blood immune parameters in dairy calves and immune parameters in cow's milk

Early separation of cow and calf is still common practice in dairy production systems, but interest in calf rearing with cow contact has been constantly increasing in recent years. We tested the hypothesis that calves suckling their mothers twice a day would benefit with regard to behaviour and health traits until four months of age, when compared to twice daily teat bucket fed calves, fed with comparable milk amounts. Moreover, the effect of calf contact beyond the colostrum period on immunoglobulin G (IgG) and lactoferrin content in cow’s milk was investigated in weeks 3, 8, 12 and 16 post partum. We conducted on-farm trials on two organic farms from 2018 to 2020, where we randomly assigned the new born calves by sex and parity status of the mother (primi- or multiparous) to either teat bucket feeding (BF, n = 30 cow-calf couples, 2 ×3–5 L/d warmed bulk milk) or mother suckling (MS, n = 28 cow-calf couples, 2 ×30 min contact after milking). MS calves performed less cross-sucking, but manipulations of objects did not differ between feeding treatments nor did avoidance distance towards humans. Clinical scores on vitality, body condition, indicators for diarrhoea and respiratory disorders, and number of medical treatments differed between farms, but not between feeding treatments. Lactate level (stress indicator) revealed contradictory results between farms (farm 1: BF>MS, farm 2: BF≤MS). Glucose content (indicator of energy level) and packed cell volume (low values indicating anaemia) were higher in MS compared to BF calves. No difference between feeding treatments was found with regard to the immune status indicators mean total protein and IgG content in calf serum. Consistently, average IgG content in cow’s milk did not differ between cows with or without calf contact and showed a clear decrease with time. The variability of lactoferrin content in milk was higher in cows with calf contact, but its average did not differ between feeding treatments nor did it change with time. We conclude that even part-time mother contact twice daily is a means to reduce abnormal behaviour, i.e. cross-sucking, as it satisfies sucking needs of calves better than teat bucket feeding. Although health traits did mostly not differ between feeding treatments, differences between farms underline the influence of management factors on calf health. Cow-calf contact twice daily had no effect on the build-up of the active immune defence until the age of four months