Animal Science Department

 

Date of this Version

Summer 6-20-2011

Comments

A Dissertation Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Doctor of Philosophy, Major: Animal Science, Under the Supervision of Professors Galen E. Erickson and Rick N. Funston. Lincoln, Nebraska: August, 2011

Copyright 2011 William A. Griffin

Abstract

Three experiments were conducted to determine the effect of calving season and cow wintering systems on cow and calf performance and economics from conception to slaughter, the effect of supplementing steers dried distillers grains while grazing cool season dominated meadow, and a meta-analysis was conducted to determine the effect supplementing dried distillers grains to cattle in forage based growing systems. In the first experiment, cows were bred to calve in spring, summer or fall. Calves from each system were managed as calf-feds or yearlings and followed through finishing. Altering calving season impacted cow BW and BCS but did not affect re-breeding performance or the percent of cows to calve. However, fall calving cows produced fewer weaned calves compared to spring and summer calving cows. In addition, there was a significant effect of calving season on calf finishing performance and economics. Wintering system did not affect performance or profitability of cow systems. The second study evaluated dried distillers grain supplementation to steers grazing cool season meadow. Results from this study suggest that lower levels of DDGS supplementation (0.6% BW) do not effect summer ADG or ending BW. However, when supplementation was increased (1.2% BW) ADG and ending BW were increased. In addition, supplementing dried distillers grains to calves grazing cool season meadow did not affect subsequent feedlot performance but BW at harvest was greater for steers supplemented dried distillers grains. The third study, evaluated dried distillers grains supplementation to cattle in forage based growing systems across multiple studies. Results from this study indicate that cattle supplemented dried distillers grains have greater gains during summer grazing. In addition, increasing the level of dried distillers grains supplementation results in a quadratic increase in ADG and ending BW. Supplementing dried distillers grains resulted in increased overall intake but decreased forage intake with increasing level of dried distillers grains.

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