Document Type

Dissertation - Open Access

Award Date

2025

Degree Name

Doctor of Philosophy (PhD)

Department / School

Animal Science

First Advisor

Zachary Smith

Abstract

The objective of this dissertation was to investigate how phytogenic feed additives and a pulse feeding monensin sodium strategy would affect growth performance in the receiving and finishing feedlot phases. Three randomized complete block design feedlot experiments and one pooled analysis were conducted to determine the effects of the feed additives and management strategies used in newly weaned and finishing beef cattle. The objective of these experiments were 1) determine if a blend of capsicum oleoresin, clove essential oil, and garlic essential oil (CCG) influences cattle performance, sera metabolites or health outcomes during the feedlot receiving phase; 2) determine if CCG influences growth performance and carcass traits during the finishing phase; 3) pool data from 4 studies to determine the effects of supplementation of CCG on growth performance of steers and intact-bulls; and 4) evaluate the effects of pulse feeding monensin sodium on growth performance, carcass characteristics, and liver abscesses in feedlot cattle. Experiment 1 used Charolais × Angus steers (n = 256; iBW = 273 ± 26 kg) in a 56 d receiving trial. Steers were allotted to 1 of 32 pens (n = 8 steers; 8 pens/treatment) and assigned to treatments: no test product (MON); CCG at 125 mg/steer/d (CCG125); CCG at 250 mg/steer/d (CCG250); or CCG at 500 mg/steer/d (CCG500). MON and CCG500 had greater DMI (quadratic effect; P = 0.01). However, CCG did not improve ADG, nor G:F (P ≥ 0.15). On d 14, CCG500 had elevated NEFA compared to the other treatments (P ≤ 0.05). Ceruloplasmin was decreased (P = 0.04) in steers from CCG250 and CCG500. There was no effect of supplementation on health outcomes (P ≥ 0.12). Experiment 2 used Charolais × Angus steers (n = 96; iBW = 391 ± 34.0 kg) in a 144 d feedlot finishing trial. Steers were weighed and allotted to 1 of 14 pens (6 to 7 steers; 7 pens/treatment) and assigned to 1 of 2 treatments: control diet without the test product (CON) or a diet including CCG at 500 mg/steer daily (CCG). There were no differences (P ≥ 0.10) in any growth performance outcomes from d 1 to 35, 36 to 70, or 71 to 98. From d 99 to 144 steers from CCG tended to have 5% greater average daily gain (P = 0.09) and 8% improved feed conversion (G:F) (P = 0.01). No differences (P ≥ 0.15) were noted for cumulative growth performance measures. No differences were noted for any carcass measurements or categorical carcass outcomes, nor lung or liver health outcomes (P ≥ 0.15). For study 3, data was pooled from experiments in South Dakota (n = 2) and Oklahoma (n = 2), and 1701 steers and 341 intact bulls were used with an iBW of 320 kg (SEM = 1.3) and enrolled into 64 pens (32 pens per treatment) with 6 to 80 head per pen. Within each study, pens were assigned to 1 of 2 treatments: 1) non-supplemented control (CON); 2) supplemented with 500 mg/steer daily of CCG. Receiving and finishing period were analyzed separately and combined No statistical differences were observed for any growth performance measurements during the receiving period (P ≥ 0.16). However, during the finishing period, supplemented steers had improved G:F by 2.3% (P = 0.04) and tended to have a greater ADG by 1.7% (P = 0.07). When the data was analyzed combined, steers that were supplemented with CCG had improved G:F by 2.8% (P = 0.02) and ADG tended to be 2.0% greater (P = 0.07). Experiment 4 used Charolais × Angus steers (n = 64; initial shrunk BW = 450 kg) in a 165 -d finishing feedlot trial. Steers were allotted in 1 of 10 pens (n = 6 to 7 steers; 5 pens/treatment). Treatments were 1) continuous monensin sodium feeding (MON) 2) pulse feeding monensin sodium (PF). The monensin sodium feeding regimen for PF entailed a 28-d administration period, followed by a subsequent 28-d withholding period without monensin. There were no differences (P ≥ 0.11) in any growth performance outcomes from d 1 to 111, and 140 to 165. However, from d 112 to 139, MON steers tended to have greater ADG (P = 0.09), and improved G:F (P = 0.02). No differences were noted for cumulative growth performance (P ≥ 0.59). No differences were noted for any carcass measurements or categorical carcass outcomes, nor liver health outcomes (P ≥ 0.34). The results from the studies in this dissertation suggest that supplementation with CCG positively influences growth performance in beef steers and intact bulls fed diets containing monensin sodium. Furthermore, this response is consistent across multiple phases of growth and management conditions. Additionally, pulse feeding monensin sodium did not compromise overall growth performance or carcass characteristics compared to continuous supplementation. Notably, comparable performance was achieved using only half the total monensin sodium dosage provided to the MON group. These findings indicate potential for both strategies to enhance production efficiency. Further research is warranted to investigate interactions with diet composition, cattle type, and management systems to optimize their application in commercial feedlot settings.

Library of Congress Subject Headings

Beef cattle -- Feeding and feeds.
Beef cattle -- Growth.
Feed additives.
Antibiotics in animal nutrition.
Monensin.

Publisher

South Dakota State University

Download

Included in

Beef Science Commons

Share

COinS
 

Rights Statement

In Copyright