More Milk = Longer Weaning Time
Dr. Trevor DeVries at a dairy conference in Minnesota summarized his thoughts relating levels of milk intake of preweaned calves to method of reducing milk intake, weaning timing, feed type and housing management. [as reported in Progressive Dairy, November 7, 2019, pp49-50]
He observed that when calves are fed enough milk to achieve a 2 pounds a day gain from milk their initial calf starter grain intake is delayed. That means different weaning management is needed compared to calves that are limit-fed milk.
Recall, our goal for calves being weaned is to maintain a level amount of usable energy for the calves both before and after weaning - a consistent level. If we get a drop in energy at weaning we will see an undesirable drop in growth as well.
His research showed that among calves fed for high rates of gain preweaning (high milk feeding) when calves weaned at 8 weeks of age (reduced milk ration spread over 2 weeks) were compared to those weaned earlier at 6 weeks later and longer weaning resulted in maintained their growth rates through the weaning process.
His calf starter grain intake goal at the time all milk feeding is ended is 4.5 pounds of calf starter gain daily. [I can add here this should be higher during cold weather months.]