Document Type

Dissertation - Open Access

Award Date

2021

Degree Name

Doctor of Philosophy (PhD)

Department

Animal Science

First Advisor

Joseph P. Cassady

Second Advisor

Zachary K. Smith

Keywords

Beef, Feedlot, Heat stress, Rye, Silage, Systems

Abstract

Three studies were undertaken to examine strategies to mitigate environmental stress faced by Northern Plains cattle feeders. In the first study, 46 feedlot managers from SD (n = 21), MN (n = 6), and NE (n = 19) were surveyed on use and perceptions of heat stress (HS) mitigation strategies. All respondents avoided cattle handling during heat stress events and incorporated some method of HS mitigation. Buildings or shades were perceived as the most successful strategy (60.9%) and were most commonly named as strategies managers would like to employ (63% for shades and 17.4% for buildings). Increasing dietary corn silage inclusion is a method to deal with challenging weather either by expanding the harvest window or to salvage weather stressed crops. One hundred ninety steers [initial BW 420 kg (SD 24.7)] were used in a randomized complete block design to evaluate the effects of feeding two types of silage germplasm at two inclusion rates. A 2 × 2 factorial treatment arrangement was used with either a conventional hybrid or a hybrid with increased expression of alpha-amylase (Syngenta Enogen Feed corn, Syngenta Seeds, LLC) fed at either 12% or 24% of diet DM. No hybrid by inclusion rate interactions were detected for live growth performance (P ≥ 0.15). Growth performance was unaffected by silage hybrid (P ≥ 0.35). Feeding 24% silage reduced ADG and G:F (P ≤ 0.05), but increased beef produced per ha (P = 0.05). Hybrid cereal rye offers agronomic benefits as a rotational crop, but knowledge is lacking regarding feeding value in finishing beef diets. Two hundred and forty steers (initial BW 404 ± 18.5 kg) were used in a finishing experiment to evaluate the effect of hybrid rye (KWS Cereals USA, LLC, Champaign, IL) as a replacement for dry-rolled corn (DRC). Four treatments were used in a completely randomized design where DRC was replaced by rye (DRC:rye, 60:0, 40:20, 20:40, 0:60). Increased rye inclusion linearly decreased final BW, ADG, and G:F. Estimated NEm and NEg values for rye when fed at 60% of DM were 1.90 and 1.25 Mcal/kg, respectively.

Format

application/pdf

Number of Pages

173

Publisher

South Dakota State University

Rights

Copyright © 2021 the Author

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