Some of the most common conversations among calf raisers relate to weaning age. What is the best age to wean calves? What is the cost versus benefit of various weaning ages? And what milestones should calves be hitting for successful weaning? 

The results achieved by many calf operations suggest that there is no singular, “perfect” weaning age. Two months of age is common, but some operations wean successfully at as early as 5 weeks. Any age range in between or even beyond can be effective, provided calves are delivered the correct nutrients and ­­­­­hit appropriate growth rate targets.

Table 1 lays out the expected average daily gain (ADG) and bodyweight targets for calves fed various levels of daily milk solids, and for different lengths of the milk-feeding phase. A few important notes related to this data include:

(1)   Early weaned calves (5 weeks -- Holsteins): Growers who wean calves early (5 weeks) often have the goal of minimizing milk replacer input costs and getting calves eating starter grain earlier in life. A typical feeding program would be 1.2 lb. of milk solids per day (40 lb. solids per calf). These calves are often shipped from multiple source farms and sometimes approach 1 week of age by the time they arrive to the farms that raise them. Their initial health status can be poor to average and sometimes they arrive dehydrated. The labor requirement for these calves can be intensive. Realistically these calves will gain approximately 0.8 to 1 pound daily pre-weaning and 1.4 to 1.5 pounds daily post-weaning until approximately 2 months of age. If they post higher ADG than this – particularly in the preweaned phase -- it is typically because they were dehydrated on arrival and that initial body weight is deceivingly low.   

(2)   Later weaned calves (8 weeks -- Holsteins): Holstein and Holstein-cross calves can be fed a range of milk replacer solids, with commensurate gains expected depending if they are fed solids at a low (1.2 lb./day, 70 lb. solids/calf); moderate (1.5 lb./day, 85 lb. solids/calf), or high (2.0 lb./day, 110 lb. solids/calf) level. When looking at most studies reported in expert-reviewed journals, such as the Journal of Dairy Science, few Holstein calves have been reported to double their birth body weight on any program by 2 months of age. However, there are many farms and farm advisors who report greater growth rates than are reported in controlled research.

(3)   Later weaned calves (8 weeks -- Jerseys): Growth of Jersey calves is different than that of Holsteins. Most people wean Jersey calves around 8 weeks of age. Feeding programs are typically a low program of approximately 1 lb. of solids daily (55 lb. solids/calf), or a high program of approximately 1.5 lb. of solids daily (85 lb. solids/calf).

When calves are fed the high milk solids program, their growth rates pre-weaning are faster than lower feeding rates. However, their growth rates post-weaning are typically less. The reason for lower growth rates post-weaning in calves fed high rates of milk solids is that their rumens do not develop as much pre-weaning and digestion of the dry feeds are reduced. So, calves on high milk solids programs are often of similar body weights at 4-plus months of age as calves fed moderate programs.

The net conclusion is that calves can perform well at a range of feeding rates and weaning ages. But each individual farm should have goals in place and measure performance to ensure they are maximizing productivity or striving to improve a metric with time. If your calf weights at 2 months of age are below the values listed in Table 1, set weights that are close to these figures to be your goal. If you are at these weights, set a 2 months-of-age goal of 5 to 8 pounds more. If you are over these weights now, then maybe your goal should focus on another metric like improving health, lowering costs, and managing labor differently.

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