Implications of beef heifer development systems and lifetime productivity

Authors: ENDECOTT, RACHEL - Montana State Extension Service; FUNSTON, R - University Of Nebraska; MULLINIKS, J - New Mexico State University; Roberts, Andrew

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/11/2012
Publication Date: 10/24/2012
Citation: Endecott, R.L., Funston, R.L., Mulliniks, J.T., Roberts, A.J. 2012. Implications of beef heifer development systems and lifetime productivity. Journal of Animal Science. 91:1329-1335.

Interpretive Summary: Research conducted over the last decade comparing traditional, more intensive systems on heifer development strategies to more extensive systems using less feed and relying on compensatory gain reveals the need to re-evaluate industry guidelines. Recent research indicates that developing heifers to weights at time of first breeding that are lighter than those traditionally targeted can reduce development costs while not impairing reproductive performance. One limitation of most research concerning influences of nutrition on heifer development and cow reproductive performance is little or limited consideration of long-term implications. Heifer development protocol and other management strategies have a great potential impact on cow retention and thus overall production efficiency. While limited information exists about the impacts of heifer development strategies on cow longevity, data from other species implies that limiting caloric intake during juvenile development can increase lifespan. Establishing the impact of heifer development protocols on longevity is complex, requiring consideration for nutritional factors following the start of breeding and through subsequent calvings. Factors to consider include the resulting maintenance requirements and behavior traits associated with development protocols. For example, developing to lighter weights prior to first breeding season may be advantageous in maintaining positive energy balance or adapting to negative energy balance through the breeding season in many range settings. Likewise, heifers developed under a range setting may be better adapted to maintain desired metabolic status during breeding than heifers reared in a pen or developed at a high rate of gain. Adequate growth and development to ensure little calving difficulty can be of critical importance for longevity; however, providing additional supplemental feed during postweaning development to accomplish this may be less efficient than later in development. Ultimately, financial requirements of any development system must be evaluated in conjunction with duration of production to establish implications on production enterprises.

Technical Abstract: Research emphasis has been placed on heifer development strategies in recent years, comparing traditional, more intensive systems to more extensive systems using less feed and relying on compensatory gain to reach a target BW. Recent research has suggested that developing heifers to a lighter target BW at breeding (50-57% of mature BW compared to 60-65% BW) reduced development costs while not impairing reproductive performance. One limitation of most research concerning influences of nutrition on heifer development and cow reproductive performance is little or limited consideration of long-term implications. Longevity has a relatively low heritability; thus heifer development and other management strategies have a greater potential to impact cow retention. While limited information exists about the impacts of heifer development strategies on cow longevity, data from other species implies that limiting caloric intake during juvenile development can increase lifespan. Establishing the impact of heifer development protocols on longevity is complex, requiring consideration for nutritional factors following the start of breeding and through subsequent calvings. Factors to consider include the resulting maintenance requirements and behavior traits associated with development protocols. For example, developing to lighter target BW may be advantageous in maintaining positive energy balance or adapting to negative energy balance through the breeding season in many range settings. Likewise, heifers developed under a range setting may be better adapted to maintain desired metabolic status during breeding than heifers reared in a pen or developed at a high rate of gain. Adequate growth and development to ensure little calving difficulty can be of critical importance for longevity; however, providing additional supplemental feed during postweaning development to accomplish this may be less efficient than later in development. Ultimately, financial requirements of any development system must be evaluated in conjunction with duration of production to establish implications on production enterprises.