Introduction

Missouri ranks second in the nation in total number of beef cows with more than two million cows on 60,000 farms across the state. Income from the forage-based beef cattle industry represents the largest source of agricultural revenue within Missouri and presents significant potential to further increase Missouri's on-farm income and total agricultural revenue. The profitability of cow/calf operations in Missouri and throughout the United States is influenced largely by pounds of calf weaned per cow exposed for breeding. Improvements in production efficiency are possible and can be expected to occur with improvements in reproductive management.

Female replacement strategies have one of the greater long-term effects on profitability within a cowherd as any other decision made by a cow-calf producer. Producers must evaluate long and short-term effects of replacement choices and the combined sensitivity of those choices to market price and long-term reproductive integrity of their herds. Decision-making systems that focus only on the short-term effects of female replacement strategies do not measure such things as: reproductive soundness, replacement rate, comparative productive capacity between heifers and cows, death and morbidity rates, disease incidence, conception rates, comparative pregnancy distribution between heifers and cows, calving interval effects on weaning weight and prices, and effect of birth weight on dystocia and subsequent reproduction.

Low adoption rates by farmers of selected management practices designed for improvement of replacement beef heifers suggest that sufficient efforts to demonstrate the utility of these practices have not been made. Because of the obvious potential to improve production, reproductive efficiency, and individual farm income we propose the development of a comprehensive educational program for beef producers in Missouri focusing on development of the replacement beef heifer.

Background

Selection and management of replacement beef heifers involve decisions that affect future productivity of an entire herd. Programs to develop heifers have therefore focused on the physiological processes that influence puberty. Age at puberty is most important as a production trait when heifers are bred to calve as two-year-olds and in systems that impose restricted breeding periods. The number of heifers that become pregnant during their first breeding season and within a defined time period is correlated with the number that exhibit estrus early in the breeding season.

The decision to breed heifers as yearlings involves careful consideration of the economics of production, and the reproduction status and breed type or genetic make-up of the heifers involved. A number of factors influence the ability of a cow to calve in a given year and successively over a number of years. Heifers that calve early during their first calving season have higher lifetime calf production than those that calve late. Because most calves are weaned at a particular time rather on a weight-constant or age-constant basis, calves born late in the normal calving season are usually lighter at sale time than those born early. This tends to decrease the total lifetime profitability of their dams. In many cases subjective methods of selecting replacement heifers have not afforded suitable focus on reproductive traits. The ability to identify heifers with the greatest reproductive potential prior to the breeding season should result in increased reproductive efficiency resulting in improvements in total cowherd productivity and profitability.

Rationale

Results from USDA's National Animal Health Monitoring System (NAHMS) beef cow-calf studies indicate that a small percentage of farms nationwide utilize specific management procedures for replacement beef heifers.

These practices, despite their potential impact and resulting contribution to the reproductive integrity of an entire herd, both short and long-term, have gained only marginal acceptance. These practices help to ensure that heifers entering a herd as raised or purchased replacements will contribute to the general performance and productivity of an entire cowherd immediately and more importantly long-term. These criteria provide an objective assessment of the postweaning to prebreeding development phase and a useful means of objectively selecting or culling bred replacements.

With more than two million beef cows in production in Missouri and roughly one million heifers produced annually, there is significant potential to add value to a large, untapped segment of the beef herd in this state. Currently, an estimated 15 percent of heifers produced annually are retained for breeding purposes. The remainder are fed to slaughter. Therein lies an opportunity to retain greater numbers of heifers to develop and market for breeding purposes within Missouri, surrounding states, the nation, as well as internationally.

One of the largest problem areas for cow-calf operations is the developing phase of the replacement beef heifer and related inadequacies in nutrition and management. Extension programming and industry education should provide a common ground in terms of available technology and emerging management practices. Development of a fundamental understanding of basic principles regarding animal breeding, genetics, reproductive biology, nutrition, animal health and economics are essential in making informed management decisions that sustain long-term economic viability on a farm-to-farm basis. These considerations provide the foundation upon which the Show-Me-Select Heifer Replacement Program is based.