Date of Award

Winter 12-27-2018

Level of Access Assigned by Author

Open-Access Thesis

Degree Name

Master of Science (MS)

Department

Animal Sciences

Advisor

Juan Romero

Second Committee Member

Seanna Annis

Third Committee Member

Eric Gallandt

Additional Committee Members

Brian Perkins

Jennifer Perry

Abstract

Our objectives were to evaluate the antifungal properties of technical lignins against 3 molds and 1 yeast causing hay spoilage, and for their ability to preserve alfalfa hay nutritive value. In experiment 1, 8 technical lignins and propionic acid (PRP; positive control) were tested at a dose of 40 mg/mL. The experiment had a randomized complete block design (RCBD, 4 runs) and a factorial arrangement of 3 molds × 10 additives (ADV). The effects of ADV on the yeast were also evaluated with a RCBD. Across fungi, sodium lignosulfonate (NaL) and PRP were the only treatments with a 100 ± 2.8% inhibition. In experiment 2, the minimum inhibitory (MIC) for selected technical lignins and PRP were determined. Among technical lignins, NaL had the lowest MIC across molds (< 33.3 mg/mL) and MgL for the yeast (26.7). However, PRP had values that were several fold lower across all fungi (< 3.33). In experiment 3, a RCBD (5 blocks) with a 3 (ADV; NaL, MgL, and PRP) × 4 (doses: 0, 0.5, 1, and 3% w/w fresh basis) factorial arrangement of treatments was used to evaluate the preservative effects of ADV in high moisture alfalfa hay inoculated with a mixture of the fungi previously tested and incubated under aerobic conditions. After 15 d, relative to untreated hay (14.9 ± 0.77%), DM losses were lessened by doses as low as 1% for NaL (3.39) and 0.5% for PRP (0.81). This was explained by a reduced mold count in both NaL at 3% (3.92 ± 0.55 log cfu/fresh g) and PRP as low as 0.5% (3.94) relative to untreated hay (7.76). Consequently, sugars were best preserved by NaL at 3% (10.1 ± 0.283% DM) and PRP as low as 0.5% (10.5) vs. untreated (7.99), while keeping NDF values lower in NaL (45.9 ± 0.66% DM) and PRP-treated (45.1) hays at the same doses, respectively, relative to untreated (49.7 ± 0.66% DM). Hay DMD was increased by doses as low as 3% for NaL (67.5± 0.77%), 1% MgL (67.0), and 0.5% PRP (68.5) vs. untreated hay (61.8). In the case of NDFD, 0.5% for MgL and PRP (30.5 and 30.1 ± 1.09% DM, respectively) and 1% for NaL (30.7) were the lowest doses increasing NDFD relative to untreated hay (23.3). Total volatile fatty acids were increased to the greatest extent by NaL at 3% (111.9 ± 1.3 mM) relative to spoiled hay (86.7). Across technical lignins, NaL was the best hay preservative. However, its effects were limited compared to PRP at equivalent doses. Despite not having an effect on preservation, MgL improved DMD by stimulating NDFD. Further research needs to be conducted to isolate the most antifungal fraction of NaL and to understand the stimulatory effects of MgL on fiber degradation. Keywords: hay preservation, technical lignins, ruminal digestibility.

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