Animal Science Department

 

Date of this Version

4-2012

Comments

A THESIS Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science, Major: Animal Science, Under the Supervision of Professors Richard N. Funston and Jennifer R. Wood. Lincoln, NE: May 2012

Copyright (c) 2012 Stetson Phil Weber

Abstract

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.

Advisers: Richard N. Funston and Jennifer R. Wood

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