Abstract
The weaning of dairy calves is a significant stressor which can impact on calf performance and welfare. However, many traditional methods of assessing the effects of stressors can be invasive and impractical for farmers. This study aimed to use a combination of non-invasive monitoring technologies alongside traditional measures of calf performance to examine the impact of two contrasting weaning methods commonly used on dairy farms in the United Kingdom. Ninety group-housed Holstein Friesian calves were allocated to one of two weaning methods: (i) gradual weaning (GW) with volume of milk replacer (MR) stepping down from 36 days of age and complete withdrawal of MR at 57 days of age and (ii) abrupt weaning (AW) with consistent daily volume of milk replacer and complete withdrawal of MR at 50 days of age. Feeding regimes were such that calves from both treatments were offered the same total amount of milk powder. Gradually weaned calves displayed increased solid feed intake at an earlier age when compared with AW calves. Feed conversion efficiency (FCE) was reduced in gradually weaned calves between days 36 and 49. However, there was no difference in live weight (LWT) or average daily gain (ADG) throughout this period. Abrupt weaning at 50 days of age resulted in decreased ADG and FCE between days 50 and 56. However, there were no treatment differences in ADG between days 57 and 62. Live weight tended to be increased by 2.2 kg in GW calves when compared with AW calves at the end of experiment on day 63. Frequency of unrewarded visits to the milk feeder throughout the pre-wean period was consistently increased in GW calves. Daily lying time was reduced in AW compared with GW calves in the days following abrupt weaning (days 50-55). However, these differences did not persist between days 57 and 62. Heart rate variability (HRV) tended to be decreased in GW compared with AW calves in the period following complete withdrawal of milk replacer. Findings from the current study suggest that calves offered the same total amount of milk powder can be weaned either gradually from 36 days of age or abruptly at 50 days of age without significant impact to live weight at 63 days of age. However, both behavioural and physiological data collected using the methods described could suggest that gradual weaning of calves from 36 days of age results in an increase in underlying frustration. This study highlights the potential of using a combination of non-invasive monitoring technologies in assessing calf response to common management practices.
Highlights
Weaning is a multifaceted stressor incorporating nutritional, environmental and physiological elements and is one of the most challenging periods for both producers and calves (e.g., [1]).Improper handling of stressors in early calfhood can impact negatively upon future health, welfare and productivity [2]
Calves fed restricted levels of milk are often unable to meet daily energy requirement despite consuming increased amounts of solid feed when compared with calves with increased milk allowance (e.g., [3,23]), this likely the reason for reduced Feed conversion efficiency (FCE) and average daily gain (ADG) observed in gradual weaning (GW) calves during day 36–49
This was likely due to the fact that GW calves were experiencing less of a reduction in available energy than abrupt weaning (AW) calves as they were established on over 1 kg/day solid feed in the days prior to weaning and milk replacer was reduced by only 300 g over 24 h as opposed to the 900 g reduction in AW calves
Summary
Weaning is a multifaceted stressor incorporating nutritional, environmental and physiological elements and is one of the most challenging periods for both producers and calves (e.g., [1]).Improper handling of stressors in early calfhood can impact negatively upon future health, welfare and productivity [2]. Whereby a previously unchanged milk allowance is removed suddenly over 24 h, has been associated with decreased solid feed consumption in the pre-wean period and a decrease or stall in growth rate in the period following the withdrawal of milk [3]. Practices such as step-down or gradual weaning through reduction in volume of milk over a number of days or reduction in number of milk meals have been suggested as a means of reducing the impact of weaning stress. The increased intake was not sufficient to compensate for the reduced intake of milk, leading to lower digestible energy intakes and low live weight gains in the calves weaned over
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