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Heifer development systems: dry-lot feeding compared with grazing dormant winter forage
1University of Nebraska West Central Research and Extension Center, North Platte 69101, USA. rfunston2@unl.edu
Journal of Animal Science
|April 28, 2011
Summary
Extensive winter grazing for heifers reduced production costs by $45 per head compared to traditional dry lot development. While heifers had lower body weight and puberty rates initially, final pregnancy rates were similar, and they compensated with greater weight gain after breeding.
Area of Science:
- Animal Science
- Reproductive Biology
- Agricultural Economics
Background:
- Heifer development strategies significantly impact reproductive efficiency and economic viability in beef production systems.
- Traditional postweaning dry lot (DL) development involves intensive feeding, while extensive winter grazing (EXT) utilizes natural forage resources.
Purpose of the Study:
- To compare the efficacy and economic impact of traditional postweaning dry lot (DL) heifer development with an extensive winter grazing (EXT) system.
- To evaluate the effects of these two development systems on heifer growth, puberty attainment, reproductive performance, and subsequent calving outcomes.
Main Methods:
- Two hundred ninety-nine Angus-based nulliparous heifers were assigned to either DL or EXT development over three production years.
- EXT heifers grazed corn residue and/or dormant winter grass, while DL heifers were fed a common diet.
- Estrus synchronization and artificial insemination (AI) were employed, followed by a 60-day bull exposure period.
Main Results:
- EXT heifers exhibited lower body weight gain during the winter period and at breeding, with fewer reaching puberty before breeding compared to DL heifers.
- Conception to AI and overall final pregnancy rates did not differ significantly between the two groups.
- Despite lighter body weight at pregnancy diagnosis, EXT heifers showed greater average daily gain post-breeding, resulting in similar pre-calving body weight.
Conclusions:
- Extensive winter grazing is a cost-effective heifer development strategy, reducing production costs by $45 per pregnant heifer.
- While EXT heifers may have delayed puberty and lower initial body weight, they achieve comparable reproductive success and pre-calving body weight to DL heifers.
- Winter development systems did not negatively impact calving ease, calf birth characteristics, or subsequent reproductive rates.
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