The purpose of this systematic review was to synthesize the evidence on how weaning techniques affect dairy calves’ performance, behavior, and health. The bulk of research focused on weaning age, length, criteria, and alternate weaning strategies. Starter intake, development, habits, and health were all considered outcome measurements.
The majority of research revealed that weaning calves at later ages, for longer periods of time, depending on starter consumption, or utilizing step-down or meal-based milk removal procedures had a favorable influence on overall development. Weaning based on starting intake resulted in faster development and higher feed intakes than weaning at a set younger age. Few research investigated the interaction effects of weaning strategy and milk allowance.
Weaning may result in hunger-related behaviors and decreased wellbeing, although only half of the research examined the impact of the weaning strategy on calf behavior. Weaning at a later age may minimize signals of hunger, however it is uncertain if weaning over longer periods of time or weaning via starting intake lowers or prolongs hunger.
There was little consistency among the few studies that examined calves’ oral habits. Positive welfare markers, like as play behavior, were seldom examined, yet they are critical to understanding calves’ emotional states throughout this potentially stressful diet change. The study’s major goal was seldom health, and statistical comparisons were limited due to small sample numbers.
Over the last two decades, experts have disputed which weaning procedures are most effective at fostering rumen development and growth while reducing indications of hunger and distress. Future research should incorporate behavioral measures of hunger and positive welfare to assess how the calf experiences weaning procedures.
Weaning procedures on dairy farms vary greatly, with some farmers weaning calves at a later age than others. In the UK, 32% of farmers wean calves at 8 weeks, whereas in the Czech Republic, Canada, and the United States, 31% report weaning calves at ≥10 weeks. However, some farmers still wean calves at about 6 weeks.
The choice to wean varies, with some farmers utilizing a mix of criteria to determine if a calf is ready to wean. Milk removal techniques are seldom systematically studied, however dilution of milk is a popular practice utilized by 32% of Swedish farmers and 25% of Canadian farmers that employ hand milk feeding methods.
There is a lack of understanding about appropriate weaning strategies, and agreement is required on which weaning approaches enhance development and health while decreasing hunger and discomfort. A thorough assessment of the scientific literature indicated a general dearth of research on the impact of weaning strategies on dairy calves’ performance, behavior, and health. Most research evaluated various weaning ages and durations, with just 15 looking into weaning using any other approach. Weaning at later ages or over longer periods of time was generally seen as beneficial to overall development, with no studies finding deleterious consequences despite lower or delayed beginning intake.
However, further research is needed to determine how different weaning strategies impact calves’ behavior and emotional state. weaned at a later age seems to minimize behavioral symptoms of hunger, however this is less obvious when weaned over a longer period of time or with lower intake. Future study should incorporate measures of positive wellbeing, which are sensitive to welfare concerns like as hunger and pain and may be useful in discovering low-stress weaning approaches. Due to the small sample size, no conclusions can be formed on calf health under various weaning strategies.
