Maintain Performance from Weaning to Breeding

By Dr. Lucas Mitchell, Vita Plus calf and heifer specialist
Many calf growers do a great job tracking preweaned calf growth.  However, after weaning, growing heifers tends to go by the wayside until it is time for breeding.  These “forgotten months” could potentially lead to some disappointing heifers when it comes time for breeding.

A common recommendation is that heifers should be 55% of their mature bodyweight at breeding.  Under- or overshooting this target can have direct financial implications for a farm’s bottom line.

Heifers that fall short of this goal may need to wait to be bred, which will increase feed costs and delay when they can enter the milking herd.  Furthermore, heifers bred when they are too small may have increased difficulty calving and are at a greater risk of not achieving the desired bodyweight at calving, which may decrease their ability to compete at the feedbunk and impair first-lactation milk production.

On the other end of the spectrum, heifers that exceed the targeted bodyweight at breeding may have been able to be bred earlier, which would have decreased feed costs and allowed her to enter the milking herd earlier.  In addition, heifers that are too heavy may struggle to get bred.

Know if your heifers are on track
A critical component in any heifer growing program is knowing the birth weight of calves, mature bodyweight of cattle, and the desired age at first calving.  Birth weights can be obtained by weighing calves shortly after birth, while mature bodyweights can be obtained by weighing third-lactation cattle. Research indicates profits are maximized when heifers are between 22 and 24 months old at first calving.  With these numbers, we can determine the desired weight and age at breeding, as well as the necessary average daily gain (ADG) required to accomplish that goal.  When armed with this knowledge, it is very simple to weigh heifers and determine if they are on track.

Weighing heifers doesn’t have to be a hassle.  The simplest way to incorporate weighing heifers into your schedule is to do it when heifers are moved to different pens.  Portable scales can be set up so heifers must cross them as they are loaded onto a trailer.  Another option is to weigh a load of heifers and then divide the weight by the number of heifers to determine their average bodyweight.  A weight tape can also be an inexpensive tool to estimate and track heifer bodyweights.  When using a weight tape, it is important to train employees to properly use it to ensure accuracy and consistency.  In some cases, it may be easiest if only one or two people always use the weight tape to provide consistent results.

Something else to keep in mind is that bodyweights are not necessarily needed for every single heifer.  Tracking weights for 25% to 30% of your heifers can save some time while still providing an idea of how they are coming along.  However, using this scenario, make sure a representative group of heifers is weighed and the same heifers are weighed each time, otherwise accurate ADG cannot be calculated.

Manage to maintain heifer performance
The greatest risk of inadequate growth after weaning and prior to breeding comes during the first two months after calves are weaned.  It is not uncommon for calves to experience a growth slump during this period, especially if they were previously fed accelerated milk feeding programs.  To avoid this slump, it is imperative to ensure calves are consuming adequate amounts of starter grain prior to weaning.  The general rule of thumb is for a calf to consume 2 pounds of starter per day prior to weaning.

Another risk during the first two months post-weaning is putting calves on a ration containing either too much or poor-quality forage.  This can lead to excessive sorting and impaired growth, and both can deteriorate health.  Adapting calves to new rations over the course of two to three weeks can be an effective strategy to ensure intakes are maintained.  A general recommendation is to keep calves on their preweaned calf starter for a couple weeks after weaning and introduce forage to them as a free-choice option before introducing a total mixed ration.

When it comes time for breeding, a couple heifers may either lag or surpass the rest of the group.  This shouldn’t be too concerning as some natural variation is expected.  In the case of a couple heifers lagging, it may be wise to evaluate their health records.  If they have had multiple health events, you might consider culling them and focusing efforts on your stronger replacements.  If they haven’t had any health struggles, it may be beneficial to keep them on feed until they reach the appropriate weight.

If the entire group of heifers are either too light or too heavy, the growing program should be evaluated.  The first thing to check is breeding age as breeding heifers too early or too late may result in heifers that are too light or too heavy, respectively.  Other factors to keep in mind if breeding-age heifers look disappointing are health events early in life, how they handle the transition after weaning, and the overall nutrition program prior to breeding.

Overall, the importance of tracking heifer growth prior to breeding cannot be overstated.  Breeding heifers at the proper size and age maximizes efficiency and sets these animals up to meet future growth goals at calving.  Meeting growth goals at breeding and calving greatly increases the success rate of heifers once they enter the milking herd.