With all of the ranch activities centered on feeding the cow herd, it can be easy to lose track of replacement heifers.  Heifer gains need not be overly aggressive, but does require that they reach 55 to 65 percent of their mature body weight at breeding to achieve acceptable reproductive performance.

Earlier guidelines used 65 percent of mature weight as the target for replacement heifers at breeding.  For a cow herd weighing an average of 1,100 lbs., this means that replacement heifers weigh 715 lb. at breeding.  Compare this to a 1,400-lb. cow herd where heifers should weigh 910 lb. at breeding.  This 200 lb. difference in the target weights at breeding should encourage producers to know the size of their cows to help better manage a successful growing program for replacement heifers.

Recent heifer development work at Nebraska (R. Funston, Minnesota Beef Cow/Calf Report, 2010) has indicated that successful reproductive performance and economic results can be achieved when heifers are developed to 55 to 60 percent   of mature body weight at first breeding.  The development programs used included:

  1. Grazing corn stalks with the addition of a protein supplement.
  2. Grazing winter range with the addition of a protein supplement.
  3. Conventional drylot management program. 

After the wintering period, heifers were moved to high quality spring pastures for additional gains (2.5 to 3.0 ADG) before and after breeding.  Results from all treatments showed:

Reduction of 0.5 lb. in ADG for heifers on corn stalks compared to other treatments

$45 less feed costs per heifer on either corn stalks or winter range compared to a conventional drylot management program

Puberty was delayed in heifers on grazing treatments but pregnancy rates were similar (85 to 90 percent) across all treatments

These development programs fit well with forage-based resources provided that supplemental protein and other key nutrients are made available.  Current grain markets are putting additional pressure on conventional drylot feed programs; thus supporting the need to consider how to do more with forages on hand.  The trick to realizing a savings in feed costs is to manage replacement heifers and not give up any reproductive efficiency.  A few nutritional items to consider for a successful replacement heifer program regardless of target breeding weight include:

Know the cow herd’s average mature body weight and heifer weaning weights to help you manage the development of your replacement heifers.

Focus on the use of low-cost forages available on your operation when possible; especially early in the development program, i.e., corn stalks, crop residue, stockpiled forages, etc.

If possible, time your breeding program so heifers have an opportunity to graze high quality spring forages to support compensatory gains and provide a positive energy balance.

Provide a well-fortified protein supplement with vitamin and minerals that also includes an ionophore, such as Bovatec® or Rumensin®, to help heifers increase growth performance and reach puberty earlier.

Monitor heifers ahead of the breeding season to determine cycling activity.

For related information, visit our Supplementation and Nutrition featured section. fid=Nutrion_supplements

Source:  Dr. Dan Dhuyvetter, Ridley Block Operations

Rumensin® is a registered trademark of Eli Lilly and Company, Indianapolis, IN.

Bovatec® is a registered trademark of Alpharma Animal Health, Bridgewater, NJ.