Here is an important fact: 50% of lifetime height growth and 25% of lifetime weigh gain occurs in the first 6 months of the dairy calf's life. Many calves experience post-weaning growth slump which has life long consequences.
Causes of post weaning growth slump:
1) Sudden diet change
The transition of milk based diet to grain or forage diet will disrupt the microbes living in the dairy calf's digestive tract.
This will cause a reduction in feed efficiency and growth.
2) Housing changes
Calves will need some time to adjust when they are moved to a new housing group.
This could cause a drop in feed intake.
3) Insufficient nutrition
Often times, producer will feed based on what is available rather than what do the heifers need.
Feeding what is available will lead to a nutrient gap, affecting growth.
4) Post weaning stress
Post weaning stress will weaken calves' immune systems, causing them to be susceptible to sickness such as scours, diarrhea and other digestive issue which can affect feed intake.
Calves' nutrition pre and post weaning will affect their performance later on. A diet designed to help develop the rumen and increase growth can help to reduce age at first calving and save on costs by reducing days on feed and entering milking herd earlier.
Pre-weaning calf rumen development
Post-weaning growth starts with calf rumen development in the pre-weaning phase.
When a calf is born, the rumen and papillae are not fully developed.
The growth of papillae is correlated with what the calf eats even in the first few weeks of the calf's life.
Feeding grain or calf starter pre-weaning will help to spark chemical reactions in the rumen and help it grow and develop.
Introduce high quality calf starter feed on day 3 of life and feed it throughout the pre-weaned phase will help to jumpstart the rumen prepare the calves for post-weaning transition.
Without a well developed rumen, calves cannot transition into all-forage diets after weaning which will cause reduced feed intakes and growth slumps.
Feeding heifers after weaning
Most farms have proper pre-weaning nutrition plan.
However, for post-weaning nutrition, each farm has their own approach to nutrition.
Some farms offer high forage diets, while some farms offer total mixed ration.
Rumen volume doubles 5 times from 8 - 24 weeks.
However, feeding a high fiber or fermented feed diet immediately after weaning calves will affect rumen development and long-term feed efficiency.
Feeding calf starter ad-libitum through 12 weeks of age with some free-choice hay will help to make the transition smooth and improve growth.
At 24 weeks, the rumen is fully developed and heifers are ready to transition to a fermented feed diet.
A nutrition plan focusing on rumen development in the pre and post weaning phase can help your calves avoid the post-weaning growth slump.