Utilization of Corn Residue, Winter Range, or Dry Lot in BeefHeifer Development Systems

Post-weaning heifer development systems that maximize reproductive efficiency and reduce input costs associated with feed is beneficial for cow/calf producers. Two research experiments were conducted to evaluate the effect of post-weaning development systems in beef heifers. In Exp. 1 heifers were developed on corn residue (CR), or dry lot (DL). Heifers developed in DL had increased BW after winter treatment until breeding. Both heifer groups were similar in percent of heifers cycling, AI conception, AI pregnancy, and final pregnancy diagnosis. A subset of AI pregnant heifers were blocked by weight and stratified by winter development system and individually fed using a Calan Gates System to measure individual feed intake. Heifers developed on CR, although lighter, had similar ADG and feed efficiency compared to DL heifers. Excess pregnant heifers were assigned to graze CR during late gestation based on previous heifer development. Late gestating heifers developed on corn CR had similar ADG compared to heifers developed in DL. Similarly, Exp. 2 evaluated the effect of heifers grazing dormant winter range (WR) or grazing CR during post-weaning development. Heifers developed on CR were similar in ADG and BW throughout winter development and breeding. Reproductive performance indicated a similar percent of heifers cycling and final pregnancy diagnosis between groups. A portion of pregnant heifers was blocked by weight and assigned to graze one of three corn residue fields in late gestation based on previous heifer development. Late gestating heifers developed on CR had similar ADG compared to heifers developed on WR. In summary, these experiments provide evidence to support development of heifers on dormant winter forage systems without sacrificing reproductive performance, feed efficiency, and ADG during late gestation. iii DEDICATION I dedicate this thesis to, my loving wife, Brooke, who has always loved, encouraged, and helped, during grad school and life's many trials and tribulations. iv ACKNOWLEDGEMENTS First, I would like to thank my Father in Heaven who has led me by the hand and help me overcome the challenges I have faced. Second, I would like to thank my wife Brooke, and my three little kids, Rainy, Kason, and Quade, for allowing time to work on my projects, homework, and papers. I cannot express all the appreciation you guys deserve, without having a family, grad school would have been much more difficult for me. Third, I would like to thank my parents, Jeff and Keri Jo, for aiding me in achieving my …