Track 1-08

Description

Proper development of replacement beef heifers is critical and needs to be accomplished at lower costs without sacrificing reproductive performance. The current recommendations indicate heifers should reach approximately 65% of mature body weight (MBW) at breeding for successful reproduction (Patterson et al. 1992; NRC 1996). Meeting heifer maintenance and gestation nutrient requirements are getting more economically challenged for beef producers in western Canada. Therefore, producers are moving from drylot development systems where cattle are housed and fed in pens to the adoption of extensive grazing systems (Kelln et al. 2011) in field paddocks. Limited research has been conducted to determine whether inherent differences in development systems affect reproductive efficiency of heifers. The most commonly used extensive dormant season grazing system in western Canada is pasture grazing forage bales in field paddocks (Kelln et al. 2011).

The objectives of this study were to determine: (1) the effects of developing heifers to a pre-breeding targeted body weight (BW) of either 55 or 62% MBW on dry matter intake (DMI), nutrient intake and reproductive efficiency; and (2) the effects of developing heifers in either field pasture paddocks (PG) or conventional drylot pens (DL) on development system cost over 2 seasons (2010-2012).

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Alternative Pasture Development System and Breeding Weight for Beef Heifers

Proper development of replacement beef heifers is critical and needs to be accomplished at lower costs without sacrificing reproductive performance. The current recommendations indicate heifers should reach approximately 65% of mature body weight (MBW) at breeding for successful reproduction (Patterson et al. 1992; NRC 1996). Meeting heifer maintenance and gestation nutrient requirements are getting more economically challenged for beef producers in western Canada. Therefore, producers are moving from drylot development systems where cattle are housed and fed in pens to the adoption of extensive grazing systems (Kelln et al. 2011) in field paddocks. Limited research has been conducted to determine whether inherent differences in development systems affect reproductive efficiency of heifers. The most commonly used extensive dormant season grazing system in western Canada is pasture grazing forage bales in field paddocks (Kelln et al. 2011).

The objectives of this study were to determine: (1) the effects of developing heifers to a pre-breeding targeted body weight (BW) of either 55 or 62% MBW on dry matter intake (DMI), nutrient intake and reproductive efficiency; and (2) the effects of developing heifers in either field pasture paddocks (PG) or conventional drylot pens (DL) on development system cost over 2 seasons (2010-2012).