Session: Ruminant Nutrition I: Feed Additives

287 - Effects of a Novel Rumen-protected Folic Acid Supplement on Feedlot Performance and Carcass Characteristics of Beef Steers

Thursday, July 15, 2021

8:45 AM – 9:00 AM EST

Location: Kentucky International Convention Center (KICC), L005/009

Presenting Author(s)

Erin L. Deters, n/a

Post-doctoral Research Associate
Iowa State University
Ames, Iowa

PDF Slides and Audio

Author(s)

EN

Emma Niedermayer

Iowa State University
Ames, Iowa
OG

Olivia N. Genther-Schroeder, n/a

Senior Research Scientist
Iowa State University
Ames, Iowa
CB

Christopher Blank

Iowa State University
Ames, Iowa
RC

Remy Carmichael

Iowa State University
Ames, Iowa
SH

Sarah Hartman

Iowa State University
Ames, Iowa
Elizabeth M. Messersmith

Iowa State University
Ames, Iowa
KV

Katherine VanValin, n/a

Assistant Extension Professor
University of Kentucky
Princeton, Kentucky
MB

Mark E. Branine, Ph.D.

Research Nutritionist
Zinpro Corporation
Eden Prairie, Minnesota
SH

Stephanie L. Hansen

Associate Professor
Iowa State University
Ames, Iowa

To assess effects of a novel rumen-protected folic acid (RPFA) supplement, 180 Angus-cross steers (292 ± 18 kg) were blocked by body weight to pens and randomly assigned to dietary treatments (n = 6 pens/treatment): target intake of 0 (CON), 30 (RPFA-30), 60 (RPFA-60), 90 (RPFA-90), 120 (RPFA-120), or 150 (RPFA-150) mg RPFA·steer^-1·d^-1. Steers were weighed on d -1, 0, 55, 56 (end of growing), 86, 87, 181, and 182. Liver and blood were collected (two steers/pen) before trial initiation and at the end of growing and finishing. Data were analyzed as a randomized complete block design using ProcMixed of SAS (fixed effects of treatment and block; experimental unit of pen). Liver abscess scores were analyzed using ProcGenmod of SAS. Contrast statements evaluated polynomial effects of RPFA and compared CON vs. RPFA-30. At end of growing, RPFA linearly increased plasma folic acid (P < 0.01) and linearly decreased plasma glucose (P = 0.01). Liver folic acid concentrations at end of growing were greatest for CON, RPFA-90, and RPFA-120 (cubic P = 0.01), and growing period (d 0 to 56) average daily gain and gain:feed were greatest for CON and RPFA-120 (cubic P ≤ 0.03). At end of finishing, RPFA linearly increased plasma folic acid concentrations (P < 0.01), and liver folic acid concentrations were lesser for CON vs. RPFA-30 (P = 0.04). Severe liver abscess percentage tended to be greater for CON vs. RPFA-30 (P = 0.09), while dressing percent was lesser for CON vs. RPFA-30 (P = 0.04). Overall (d 0 to 182) carcass-adjusted gain:feed tended to be greater for CON vs. RPFA-30 (P = 0.09). Although RPFA increased plasma folic acid concentrations throughout the study, feedlot performance was not improved, possibly due to low vitamin B12 status (plasma < 200 pg/mL) of steers, regardless of treatment.