Feeding on the move: assessing the effect of feeding during long-distance ferry transport on the physiology, clinical signs of disease and activity of unweaned calves

Abstract

Long-distance transport of unweaned calves and associated fasting can negatively impact their physiology, and practical strategies to mitigate extended fasting times have not been studied previously. This study aimed to assess changes in the physiology, clinical signs of disease, and activity of unweaned calves as a result of providing access to feed (milk replacer) on board a trailer during a road/ferry/road journey from Ireland to The Netherlands. Calves were transported from an assembly centre (Ireland), via lairage (France), to a veal farm (The Netherlands). Calves were provided milk replacer on-board the trailer during the ferry section of the transport using an on-board feeding system (FEED; n = 40), or included as controls (CONT; n = 60). Calves were blood sampled and weighed, and clinical signs of disease were scored prior to departure from Ireland (Day 0), upon arrival at the lairage (Day 1), upon arrival at the veal farm (Day 2), and 1−week postarrival (Day 9). A subset of calves were equipped with activity sensors and continuous glucose monitors (CGM). Most blood variables differed between FEED and CONT calves on Day 1; glucose was higher (4.8 vs 4.0 mmol/L) and beta-hydroxybutyrate (0.20 vs 0.34 mmol/L), non-esterified fatty acids (0.52 vs 0.71 mmol/L), and lactate (0.85 vs 1.25 mmol/L) were lower for FEED compared to CONT calves; no blood variables showed significant differences at the next timepoint (all P > 0.05). Clinical signs of disease and BW did not reveal significant differences between treatment groups during transport. Step count was higher for FEED than for CONT calves at the time of feeding on the ferry (172 vs 37 steps/h), but not at any other time. CGM glucose was higher for FEED calves at 21 h (5.9 vs 4.9 mmol/L) and 22 h (6.0 vs 4.9 mmol/L), but lower for FEED calves at 27 h (7.4 vs 9.3 mmol/L), 28 h (7.9 vs 9.1 mmol/L), and 30 h (7.3 vs 8.3 mmol/L). In general, blood variables showed a shift towards normal ranges after on-board feeding; however, these effects diminished following a second prolonged fasting period after lairage in France. Differences in clinical signs of disease, weights, activity, and CGM were inconsistent across time points. On-board provision of milk replacer is currently challenging but has the potential to improve the physiological status of calves. Systems need to be developed further, and more research is needed to perfect the on-board feeding of calves during transport.