Document Type

Thesis - Open Access

Award Date

2023

Degree Name

Master of Science (MS)

Department / School

Animal Science

First Advisor

Zachary Smith

Keywords

B vitamin, beef, growth, liver, steers, trace mineral

Abstract

Trace minerals (TM) and vitamins are essential to improve production output and efficiency in beef cattle. The first experiment was conducted to investigate if the delivery method of TM and Saccharomyces cerevisiae yeast culture influence growth performance and hepatic TM content of receiving steers. The second experiment evaluated the effect of supplemental protected B - vitamins to finishing steers. Experiment 1 used Charolais x Angus steers calves (n = 192; 256 ± 14 kg) in a 49-d receiving experiment. Within 36h of weaning, steers were weighed, allotted to 24 pens (n = 8 steers/pen; 8 pens/treatment) and randomly assigned to treatments: traditional receiving diet (Con); traditional receiving diet plus the “stress-pack” directly in the diet (Force); traditional receiving diet plus a low-moisture, cooked molasses block fortified with the “stress-pack” (Tub). The “stresspack” was offered the first 28 d of the 49-d experiment. Hepatic biopsy samples were collected from a subsample of steers (n = 14 steers) on the day of weaning and subsequent samples were collected from the same steer (n = 1 steer/pen) on d 14, 28 and 49 for hepatic TM concentration determination. A treatment × day interaction (P ≤ 0.01) for hepatic Cu concentration was noted. Force had greater hepatic Cu (P ≤ 0.05) compared to Tub and Con at each sampling point. Tub had greater hepatic Cu compared to Con on d 14 and 28 (P < 0.05), but was similar to Con on d 49 (P > 0.10). Force tended (P = 0.08) to have greater DMI compared to Tub from d 1 to 14. From d 15 to 28, steers offered “stress-pack” had greater DMI (P = 0.01) and tended (P = 0.07) to have greater ADG compared to Con by 12.5%. From d 29 to 49, “stress-pack” steers had greater DMI (P = 0.01) and Force consumed 6.9% more DM compared to Tub (P = 0.01). Cumulative DMI (P = 0.01) and ADG (P = 0.05) was greater for Force compared to Tub by 5.4% and 9.4%, respectively. These data indicate that application of a “stresspack” in diets offered to newly-weaned cattle enhanced production responses, but delivery method influences DMI and daily gain. In experiment 2, steers (n = 246; initial shrunk BW = 411 ± 25.8 kg) from two sources, were used in a 126-d experiment to evaluate use of a rumen-protected B – vitamin blend (RPBV). Within 48 h after arrival, steers were individually weighed and processed. Steers were then allotted to one of 24 pens (n = 10 to 12 steers; 8 pens/treatment) and randomly assigned to 1 of 3 treatments: 1) No RPBV; 2) RPBV1 at 1 g/steer·d1; 3) RPBV2 at 2 g/steer·d1. During the first 14 d cattle received two transition diets. From d 15 to 126 cattle were fed the final diet containing [dry matter (DM) basis]: 53% dry-rolled corn; 23% corn silage; 20% MDGS; and 4% suspended supplement. No differences (P ≥ 0.13) were found for DMI, live final BW, ADG, or G:F. Carcass-adjusted final BW, ADG, and G:F were not influenced by treatment (P ≥ 0.59). Hot carcass weight (HCW), dressing percentage, marbling score, kidney-pelvic-heart fat, or BW at 28% empty body fat did not differ among treatments (P ≥ 0.11). Ribeye area (REA) was altered (quadratic effect, P = 0.02) by treatment; steers from RPBV1 had decreased REA compared to others. Additionally, calculated yield grade (YG) and calculated retail yield (RY) were altered (quadratic effect, P ≤ 0.01) by treatment; steers from RPBV1 had increased YG and decreased RY compared to others. Estimated empty body fatness tended (P = 0.06) to be greater from steers fed RPBV compared to control. Overall, USDA YG distribution was altered by dietary treatment (P = 0.01). The proportions of YG1 and YG5 carcasses were unaffected by treatment, but there was a shift in the proportion of carcasses that graded YG2, YG3, and YG4 among treatments. Distribution of USDA Quality Grade was not altered by treatment (P = 0.53). No differences were observed on liver abscess prevalence or severity among treatments. The use of RPBV altered carcass muscularity and rib fat accumulation influencing the overall YG distribution. However, RPBV did not appreciably influence any cumulative growth performance measures or liver abscess outcomes in these steers.

Library of Congress Subject Headings

Beef cattle -- Feeding and feeds.
Feed additives.
Trace elements in animal nutrition.
Vitamin B in animal nutrition.

Number of Pages

99

Publisher

South Dakota State University

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Rights Statement

In Copyright