Individual characteristics in early life relate to variability in weaning age, feeding behavior, and weight gain of dairy calves automatically weaned based on solid feed intake

摘要

Little is known about factors affecting individualvariability in weaning age, feeding behavior, andgrowth of dairy calves. The objectives of this studywere to (1) describe early-life individual characteristicsof dairy calves and how these relate to weaning age,feeding behavior, and performance during the first 15wk of age, and (2) to identify which of these individualcharacteristics predict weaning age of calves automaticallyweaned based on solid feed intake. Early-lifecharacteristics of calves (n = 43) included scores forvitality at birth, drinking ability, learning ability to usethe automated milk feeder in a group pen from d 1 ofage, and personality traits assessed using exposure toa novel environment, a human, and an object at d 21of age. Calves received 12 L/d of milk until d 30 whenmilk was reduced by 25% relative to the individual’sprevious 3-d intake average. Calves were weaned basedon intake of solid feed (milk reduced by 25% at eachof 2 intermediate solid feed intake targets, 225 and675 g/d), and were weaned when they consumed 1,300g/d of solid feed, resulting in variable weaning ages. Aprincipal component analysis identified 5 factors thatwe labeled as low vitality, fearful, strong drinker, slowlearner, and exploratory-active. Calves that were slowlearners weaned at a later age, whereas fearful calvesweaned earlier. No other early-life individual characteristicswere associated with weaning age. Other characteristics(low vitality, strong drinkers, and exploratoryactive)were associated with some measures of feedingbehavior, feed intake, and growth, especially during thepreweaning period. Measures of early solid feed intake(age to start eating and total preweaning intake) werebest able to predict weaning age of calves. Individualearly-life characteristics and measures of early solid feedintake can identify calves likely to do well or struggleduring weaning.