Author
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Roberts, Andrew |
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Submitted to: Bovine Connection Proceedings
Publication Type: Proceedings Publication Acceptance Date: 11/1/2009 Publication Date: 12/2/2009 Citation: Roberts, A.J. 2009. Beef cow longevity and efficiency with limited feeding management. Bovine Connection Proceedings p. 13-15. Interpretive Summary: Feed consumed by the cowherd is a major cost of beef cattle production. Much of this cost is for harvested feed provided to supplement developing heifers and pregnant cows through periods when quality and quantity of rangeland forage may be limiting. An abundance of research concerning the influences of nutrition on heifer development and cow reproductive performance has resulted in guidelines on body conditions that reflect a nutrient status that will optimize reproductive performance. However, a major limitation of the research is a focus on short term effects (single production year) with little consideration of long-term implications. Providing cows with sufficient feed to maximize probability of successful reproduction may not result in maximum biological or economical efficiency. Feeding to maximize reproductive rate does not result in differential retention between females with high and low feed requirements. In contrast, managing cows undr reduced feed inputs would more likely result in culling of cows with high feed requirement due to reproductive failure. Furthermore, increasing the proportion of cows with reduced feed requirements are scarce or costly. In addition to reducing cost of development, rearing young animals under caloric restriction has been shown to prolong lifespan in other species. Increasing lifespan can result in decreased replacement rate (more calves to sell) and greater proportion of cows at peak productivity (maximum productivity is between 4 to 11 yrs old). Results at the present time indicate that the long term implication of restricting levels of feed during postweaning development and throughout winter supplementation is improved production efficiency due to decreased utilization of harvested feed, increased efficiency of cows and an apparent alteration of partitioning of nutrient utilization (increased BCS and decreased calf weight) that results in increased retention of cows beyond 5 years of age. Technical Abstract: Feed consumed by the cowherd is a major cost of beef cattle production. Much of this cost is for harvested feed provided to supplement developing heifers and pregnant cows through periods when quality and quantity of rangeland forage may be limiting. An abundance of research concerning the influences of nutrition on heifer development and cow reproductive performance has resulted in guidelines on body conditions that reflect a nutrient status that will optimize reproductive performance. However, a major limitation of the research is a focus on short term effects (single production year) with little consideration of long-term implications. Providing cows with sufficient feed to maximize probability of successful reproduction may not result in maximum biological or economical efficiency. Feeding to maximize reproductive rate does not result in differential retention between females with high and low feed requirements. In contrast, managing cows undr reduced feed inputs would more likely result in culling of cows with high feed requirement due to reproductive failure. Furthermore, increasing the proportion of cows with reduced feed requirements are scarce or costly. In addition to reducing cost of development, rearing young animals under caloric restriction has been shown to prolong lifespan in other species. Increasing lifespan can result in decreased replacement rate (more calves to sell) and greater proportion of cows at peak productivity (maximum productivity is between 4 to 11 yrs old). Results at the present time indicate that the long term implication of restricting levels of feed during postweaning development and throughout winter supplementation is improved production efficiency due to decreased utilization of harvested feed, increased efficiency of cows and an apparent alteration of partitioning of nutrient utilization (increased BCS and decreased calf weight) that results in increased retention of cows beyond 5 years of age. |
