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Effect of an ad libitum milk supply during the first three weeks of life of dairy calves on heart rate and heart rate variability during feeding.

S. Wiedemann

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06-23-2020

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Abstract:

T64
Effect of an ad libitum milk supply during the first three weeks of life of dairy calves on heart rate and heart rate variability during feeding.
S. Wiedemann*1, L. Prokop2, G. Hoffmann3, M. Kaske4. 1Rhine-Waal University of Applied Sciences, Livestock Sciences and Environmental Impacts Kleve, Germany, 2University of Kiel, Institute of Animal Breeding and Husbandry Kiel, Germany, 3Leibniz Institute for Agricultural Engineering and Bioeconomy, Department Engineering for Livestock Management Potsdam, Germany, 4University of Zurich, Vetsuisse Faculty, Department for Farm Animals Zurich, Switzerland.

The objective of this study was to investigate the effect of nutrient supply during early postnatal life on heart rate (HR) and heart rate variability (HRV) as indicators of the cardiac response. Male and female calves were fed either a restrictive milk allowance twice per day (6 L/d; RES; n = 28) or an unlimited amount of milk (ad libitum; ADL; n = 28) during the first 3 weeks of life. All calves were housed in individual straw bedded hutches. To study the cardiac response to the feeding process on d 21 of life HR, HRV and variables in the time- and frequency domain were measured continuously using a portable recording system. Six time windows of 5 min each were chosen: resting time at 05.00 a.m., start of personnel activity in the barn, 15 min before feeding, during feeding, 15 min after feeding and 1 h after feeding. During resting RES calves had a very low HR (95.6 � 6.1 beats per min) indicating a reduced metabolic activity in comparison to ADL calves (120.4 � 6.0 beats per min; P < 0.05). During feeding HR reached peak values which were comparable in both groups, however the increase in HR was higher in RES calves. HRV variables of the time- and frequency domain indicated a shift toward a sympathetic dominance in the balance of the autonomic nervous system during feeding time particularly in RES calves. Differences between resting and feeding values were demonstrated in RES calves at low frequency and high frequency power, whereas no differences were observed in ADL calves. It can be concluded that particularly the increase in the HR indicated higher excitement in RES calves during times of feeding.

Keywords: heart rate, heart rate variability, ad libitum feeding of calves.