By overcoming nutrient demands for lactation, early weaning offers a viable alternative to improve reproductive performance
Mid-summer can be a great time of year: grass is growing, cows are in good body condition due to lush forages this spring, and calves are old enough to be really growing and muscling-up. To me, there is nothing better than watching a calf who is old enough to be out grazing and growing on his own, and usually oblivious to where his mom is.
Often, because we like the look of those growing calves so much, the majority of beef cattle producers (53% to be exact), decide when to wean their calves primarily based on calf weight or age. Interestingly, according to USDA survey data (Figure 1), only 7% of producers consider cow body condition score as the primary factor to determine weaning time.
I’ll be the first to admit it – it’s not very appealing to even look at young, small, and lightweight calves, never mind weaning them like that. We all love to see big, heavy, stout calves at weaning time. But, numerous studies have demonstrated that weaning calves early can be an effective tool to help improve reproduction and forage availability by reducing nutrient requirements of the cows.
Lactation drain: The case for early weaning
A typical beef cow requires about 10 megacalories of energy per day to maintain her body tissues. When she is lactating, the same cow requires approximately 3 to 6 additional megacalories per day, depending on how many days she has been lactating.
When a calf is weaned earlier than normal, the cow’s overall nutritional requirements are reduced when her lactation stops. Non-lactating cows require about 20-35% fewer nutrients than lactating ones. Interestingly, Oklahoma researchers reported that cows consume about 1% of their body weight less after early weaning. Ultimately, fewer nutrients required per cow means more feed to go around for other more appropriate uses.
Among researchers, it is generally agreed that weaning early can offer these advantages:
- Cows are able to improve their body condition score prior to winter feeding,
- Reproductive performance can improve (as seen by more cows pregnant during the season and/or more cows pregnant earlier in the season) due to reduced nutritional demand and improved body condition scores,
- Greater forage availability for cows or other livestock, including reduced demand on pastures,
- Improved calf performance in drought situations, sometimes including more desirable carcass characteristics.
Early weaning options
Typically, beef calves are weaned at about 6 or 7 months of age. In fact, beef breed associations adjust calf weaning weights to an age constant of 205 days (about 6 ¾ months). However, researchers have reported that calves can be successfully weaned as young as 1½ to 2 months of age.
Calves weaned prior to or during the breeding season (at 2 to 3 months of age) can have immediate effects on reproductive performance in that same year’s breeding season, including changes to conception rate and length of postpartum interval. However, if calves are weaned 1 to 3 months earlier than normal, reproductive performance can only be affected in the next year’s breeding season (due to elevated body condition scores at the end of the upcoming winter).
What am I giving up?
Unfortunately, early weaning does have its downfalls compared to traditional weaning. For instance, in the short-term, income will likely be reduced if calves are sold at a significantly lighter weight. But, it should be noted that lighter calves commonly sell for a higher price per pound, and calf prices also tend to be higher in late summer vs. fall. In contrast, when viewed over the long-term, more future calves will likely be born earlier in the calving season (assuming cows are in better condition and breed back sooner) and will be older and heavier at weaning time in subsequent years.
Early weaning also requires an increased focus on management, and possibly a need for improved animal facilities. Calves weaned earlier than normal can still be sold directly off the cow, but reduced income from the sale of lighter calves can be avoided if calves are pastured separately from the cowherd or placed into a feedlot and backgrounded or finished. In addition to requiring more attention to manage health problems, early-weaned calves also tend to have elevated nutritional requirements for energy, protein, and minerals.
On the positive side, weaning calves early can affect forage availability and cost related to upcoming winter supplementation. New Mexico State University researchers developed a “forage budget” to determine the effect of early weaning on forage availability. Selling calves (and cull cows) 45 days earlier saved 175,000 lbs of forage on a 100 head operation, which was equivalent to the nutritional needs of approximately 25% of the cowherd. This surplus forage can be used to improve cow body condition scores during late summer and fall.
The Bottom Line
Since milk production is a major energy drain on beef cows, adjusting time of weaning has been shown to effectively manipulate cow body condition score. When cows stop lactating, their energy requirements and feed intake reduce substantially (typically in excess of 20 to 30%).
Implementing early weaning will likely have negative short-term consequences, including the possibility for reduced income, increased costs, and the need for more intensive management. However, long-term positive effects can include improved cow body condition score, reproductive performance, and age and weight of calves in subsequent seasons, along with reduced winter supplementation cost.
In reality, early weaning probably offers the most advantage in young cows and in drought situations. Therefore, to experiment with this management option, producers should consider early weaning a portion of their calf crop (e.g. first- and second-calf cows, or old cows) this summer or fall.
Editor’s note: Two publications available on-line contain more information and suggestions for producers interested in early weaning their calves: “Early Weaning Beef Calves” by Greg Lardy and Russ Danielson (North Dakota State University) at http:// www.ag.ndsu.edu/drought/ds-8-97.htm, and “Early Weaning Beef Calves” by Clay Mathis and Manny Encinias (New Mexico State University) at www.cahe.nmsu.edu/pubs/_b/B-126.pdf.