As feed and commodity prices fall and cattle prices continue to hold firm at record levels, the incentive to add pounds with "cheap" feeds is present. Proper heifer development hinges on achieving a desired weight before breeding…yet not over-developing heifers to the point they are not prepared to live on pasture and forage-based diets the remainder of their life.
Most literature shows heifers should be developed to 65% of mature body weight, although some have had success at slightly lower percentages. For example, consider the following scenario. Heifer Ranch maintains mature cows that weigh 1400 lbs., they calve on March 1st and their cows wean 45% of their body weight. This results in heifer calves that weight 630 lbs. at weaning. If they are bred to calve on March 1st at two years of age, then she needs to be fed at a programmed gain of 1.04 ADG to weigh 910 at breeding. These numbers are surprising to some, but truth is heifers developed on a steady gain do not need high energy feeds. Develop a least-cost ration, account for "profit robbers," and target 65% of mature weight.
It is important for gain patterns to be steady. Many times I see heifers that are pushed early with creep feeds and subsequent grain until steer calves are sold. Then the heifers are forgotten. However, cattle that are losing weight have poor conception rates. It is important not to burn out heifers and then crash them … all the while expecting them to breed because they are heavy enough. In fact, heifers gaining weight during breeding are far more successful at conceiving.
Some producers that are limit feeding a heifer development ration should certainly consider adding Rumensin to the diet. This has shown to help heifers reach sexual maturity earlier and certainly can help them maintain adequate gains on a limited-fed ration.
My opinion is having heifers on a steady plane of gain, targeted for 65% of mature weight is the best nutritional management plan you can have. Make sure your mineral program is solid. Heifers gaining weight during and after breeding is a great way to help boost breeding success in heifers.
A balanced ration that results in steady, moderate gains before, during, and after breeding along with avoiding over-developing or under-developing will make you happy at preg-check time.
The heifers you are deciding to keep for replacements have a mighty big price tag on them. Proper management and development of these heifers will be crucial to making them profitable additions to the herd.