Feeding and weaning strategies to avoid the post-weaning slump

Tana Dennis for Progressive Dairyman Published on 08 March 2018

With increased emphasis on early life feeding programs for replacement heifers, the need for more information regarding successful weaning management is clear. More and more dairy farmers are feeding double, and sometimes nearly triple, the milk feeding rates that had been recommended for decades prior.

While growth rates are often excellent when wet calf milk feeding rates are high, much of the growth advantage gained is lost due to poor growth rates in the weeks following the weaning transition. Several recently published studies attribute the lost advantage, or “weaning slump,” to poor starter digestibility due to less accumulated starter intake before weaning and slowed digestive system development.

When calves are fed more than 2 pounds of milk replacer solids per day pre-weaning, reduced diet digestibility is also seen up to four weeks post-weaning. Interestingly enough, at 4 months old, calves fed 1.5 pounds of milk replacer solids per day pre-weaning have similar bodyweight and frame size as calves fed the 2 pounds of milk replacer per day.

Much of the push for feeding high amounts of milk or milk replacer has been spurred by several recent studies suggesting greater pre-weaning average daily gain increases first-lactation milk production. While the simplest way to increase weight gain is to increase energy and protein intakes by feeding more milk or milk replacer, recent studies from Penn State and the University of Minnesota have shown starter intake is equally important to pre-weaning average daily gain and the subsequent effects on first-lactation milk production.

One benefit of generating the gain from starter intake versus milk is: It positively impacts digestive system development, resulting in little to no weaning slump.

Additionally, one Cornell study linking pre-weaning weight gain to milk production in heifers also reported pre-pubertal average daily gain had a greater impact on first-lactation milk production than pre-weaning average daily gain alone. This suggests a more balanced feeding program that optimizes growth before and after weaning is needed.

Are there ways to fix the issue of low starter intake before weaning when calves are fed high amounts of milk? Studies from the Universities of Alberta and British Columbia have suggested calves should be weaned later and over a longer period of time when more milk or milk replacer is fed.

However, each of these studies had post-weaning periods of only a few days, did not measure structural growth and did not measure diet digestibility or the development of the digestive system. The Provimi research team recently measured growth and diet digestibility over time in calves fed one of four milk replacer programs:

  • 1.5 pounds per day of milk replacer and weaned over three days (6-week weaning)

  • 2.5 pounds per day of milk replacer and weaned over seven days (6-week weaning)

  • 2.5 pounds per day of milk replacer and weaned over seven days (8-week weaning)

  • 2.5 pounds per day of milk replacer and gradually weaned over 14 days (8-week weaning)

After weaning, calves were grouped by feeding program and fed a textured calf starter with 5 percent chopped grass hay until 4 months old. Calves fed 2.5 pounds of milk replacer and gradually weaned had greater starter digestibility through 12 weeks old compared to calves fed 2.5 pounds of milk replacer and weaned over seven days (Figure 1).

Week of age

However, all four treatment groups had similar bodyweight and skeletal frame size at 4 months old. Additionally, growth rates and starter digestibility were greatest post-weaning for calves fed 1.5 pounds of milk replacer compared to calves fed more milk replacer.

Excellent starter intake pre-weaning (at least 35 pounds by 6 weeks old) was a common factor from all of the studies where calves grow well post-weaning. Calves with excellent starter intake before weaning were also fed less milk replacer (1.5 pounds per day). Feed costs and feed costs per unit of growth increase with increasing milk replacer feeding rates (Table 1).

Impact of milk re;pacer feeding program on intake

Feed costs are typically $25 to $60 more per calf as feeding rates increase from 1.8 to 3 pounds of milk replacer and weaning is extended from 6 to 8 weeks old.

With milk replacer costs being six to eight times more than the cost of starter, feeding more milk replacer increases the cost to raise a calf. With no improvements in bodyweight at 4 months old, and a slight reduction in frame growth, the feed cost per pound of bodyweight gain increases on average 28 percent over eight research trials (Table 1).

Since the pre-weaned calf is the most expensive animal to feed and manage on the dairy (due to high feed costs and greater labor demands), preserving growth rates through weaning should start with a milk feeding program that fosters more starter intake to ensure efficient starter utilization and growth post-weaning.  end mark

Tana Dennis
  • Tana Dennis

  • Calf and Heifer Nutritionist
  • Provimi North America
  • Email Tana Dennis

Ways to avoid post-weaning slumps in growth

  • Feed calves about 1.5 pounds of solids daily from milk or milk replacer.

  • If you choose to feed more solids from milk or milk replacer, reduce feeding rate to 1.5 pounds per day or less for three weeks prior to complete weaning.

  • Limit fat concentration in milk replacer (16 to 18 percent is optimal) and in starter (less than 5 percent) to avoid limiting starter intake.

  • Feed textured starters with 35 to 40 percent starch prior to 4 months old to maximize digestible energy intake.

  • Limit hay provision to 5 to 10 percent of the diet from weaning to 4 months old.

  • Ensure calves have adequate amounts of clean water, even in winter.

  • Avoid multiple management procedures at weaning. Disbudding and vaccinations (and castration if feeding bulls) should be performed at least two weeks before initiating weaning protocols.

Before commenting on our articles, please note our Terms for Commenting.