Did you know that within the initial 6 months of a dairy calf's existence, half of its total stature growth and a quarter of its weight gain happens? The Dairy Calf and Heifer Association's Gold Standards notes why the period following weaning is as pivotal as the weeks leading up to it. Hence, calves in their pre-weaning stage demand significant care and attention to maintain their well-being. In other words, carefully handling weaning is necessary because any misstep can negatively affect their health and overall productivity.

Here are some helpful hints for a smooth post-weaning phase. These tips are from the experts, Dr. Donna Amaral-Phillips of the University of Kentucky Dairy Extension and Dr. Troy Wistuba of Purina Animal Nutrition.

Weaning can be stressful for calves, but a systematic approach can ease the transition. Amaral-Phillips recommends making one change at a time. While the sequence of modifications can vary based on the specific operation, calves should adapt to one change before introducing the next.

For instance, you may gradually decrease auto feeder volumes before removing them altogether. You may also reduce liquid rations to 1X feedings for several days. When moving calves to new housing, keeping them on their pre-weaning grain mixture can be beneficial. Some producers have found success by allowing calves to remain in their pre-weaning housing for a week post-weaning.

The key to changing a calf's diet is to make changes gradually. Wistuba points out that a sudden change from primary milk to a mix of grain and forage can disturb the calf's digestive microbes. He recommends starting with a high-protein (22% protein) starter grain. Feed it freely for the first 10–12 weeks until they consume 10 pounds daily. After that, for the following 12 weeks, introduce them to an 18% high-protein grower feed supplemented with free-choice hay.

Grouping after weaning should be thoughtfully done. The initial post-weaning groups should be kept small, with six or fewer calves. This setup lets the young heifers adjust to group dynamics, find water sources, and reach the feed bunk without undue competition stress. For those calves raised in auto feeder pens, it's best to keep them in their established groups post-weaning.

The well-being of dairy heifers between the ages of two and four months depends on creating user-friendly facilities. Each head should have 12 to 18 inches of feed bunk area. This clearance is designed so all animals can effortlessly access the feed trough. An ideal atmosphere contains enough air circulation without draughts, like in pre-weaning facilities. Amaral-Phillips also emphasizes the significance of offering shelter, dry bedding, and walking surfaces. It should not have any snow or mud. These factors ensure that heifers don't expend extra energy to stay warm or struggle to reach their feed.

Amaral-Phillips stressed the need to concentrate on the diet's overall protein content. Hence, when it comes to feeding heifers, the approach should prioritize their nutritional needs rather than what's readily available. She points out that young heifers, in particular, may not receive sufficient protein for skeletal growth from lower-protein grain mixes (12–14% crude protein). This is true even when combined with forages that test below 18–20% crude protein. Thus, the feed selection must align with the specific needs of the heifers to ensure proper growth and development.

Keeping coccidiosis at bay is one aspect of maintaining weaned calves' healthy growth. As Amaral-Phillips notes, if a coccidiostat like Deccox was present in the pre-weaned starting grain, including a coccidiocide like Rumensin or Bovatec in the post-weaned ration is especially important. After weaning, discontinuing a coccidiostat from the food may allow the coccidian protozoa to finish their life cycle. This will result in a lapse in coccidiosis protection.

The rumen plays a vital role in the well-being of weaned calves. While external appearances can be deceiving, internal developments are of paramount importance. Wistuba states that the rumen volume increases exponentially between 8 and 24 weeks of a calf's life, doubling five times. Beginning feedings with starter grain and offering free-choice water as soon as Day 3 after birth trigger important chemical reactions.

For one, it promotes papillae growth in the rumen wall. However, a sudden shift to a primarily forage diet upon weaning can damage this rumen growth, affecting long-term feed efficiency. Both experts stress the importance of maintaining a balanced grain diet until the 24th week. Heifers are getting ready to switch to a fermented forage diet by this stage since their rumens are developed.

Ensuring a smooth transition from the pre-weaning to the post-weaning phase is critical. This ensures you don't waste the resources invested in the early stages of a calf's life. As Wistuba aptly puts it, there's no "undo" button or method to make up any lost ground during post-weaning. Once progress is lost, you cannot regain it. It's a stark reminder that careful planning and execution in the post-weaning period are just as essential as the pre-weaning efforts. Remember, each stage builds on the successes of the previous one. All these efforts pay off in the growth and development of the calf.