Date of Award

Fall 12-20-2020

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

Anne Lichtenwalner

Additional Committee Members

Brian Perkins

Denise Skonberg

Abstract

The aim was to screen and optimize low-cost lignosulfonates (LST) as legume silage and hay preservatives to decrease losses of DM and nutritive value due to spoilage. In experiment 1, we evaluated the effects of untreated silage (0%), sodium lignosulfonate (NaL) and magnesium lignosulfonate (MgL) applied independently at 0.5, 1, and 1.5 (% w/w, fresh basis) and INO (Pediococcus pentosaceus and Lactobacillus plantarum; 5 and 4 log cfu/fresh alfalfa g, on high moisture alfalfa (Medicago sativa L.) silage nutrient preservation. Data were analyzed as a randomized complete block design (RCBD; 5 blocks) and linear and quadratic polynomial contrasts were used to determine dose rate effects for NaL and MgL and orthogonal contrasts for INO effects. At opening (d 229), both MgL and INO increased DM loss (~13.7 vs 11.3% of DM) due to a lower production of lactic acid (~7.55 and 7.83 vs 9.23% of DM, respectively) which resulted in a higher pH relative to untreated silage (~4.41 and 4.46 vs 4.33; respectively). The high acidification in untreated silage resulted in additives not reducing further the proteolysis that occurred relative to control, measured as NH3-N (~11% of N). Overall, all additives tested failed to improve the preservation of high moisture alfalfa silage nutrients. In experiment 2A, we determined the minimum inhibitory (MIC) and minimum fungicidal concentration (MFC) of 4 sodium lignosulfonates [Sappi (NaSP), Sigma-Aldrich (NaAl), Beantown (NaBT), and Spectrum (NaUM)], 1 magnesium lignosulfonate [Sappi (MgSP)], 2 chitosan sources [naive (ChNv) and microparticles (ChMp)], and propionic acid (PRP; positive control) against 3 molds and 1 yeast isolated from spoiled alfalfa hay. Our results showed that both chitosans had the strongest fungicidal activity against all the fungi tested with exception of M. circinelloides at both pH 4 and 6. Among lignosulfonates, we found that NaSp was the most antifungal and was further optimized to produce LST. However, none of the lignosulfonates inhibited the molds or yeast at pH 6. Across additives, PRP inhibited all fungal strains at both pH levels. In experiment 2B, we used a factorial combination of three preservatives (LST, ChNv, and PRP) and 5 concentrations (0, 0.25, 0.5, 1, and 2% w/w fresh basis) to determine the effects of their application on the preservation of nutrients in high moisture alfalfa hay. Data were analyzed as a RCBD replicated five times. After 23 d of aerobic storage, LST and PRP prevented DM losses to the same extent with doses as low as 0.25% compared with the untreated hay (~1.61 vs 24.0%). This was explained by reduced mold counts for as low as 1% LST (< 2.0) and as low as 0.5% PRP (< 2.0) compared with untreated hay (6.76 log cfu/fresh g). However, ChNv did not affect DM loss or molds count (~23.2% and 6.59 log cfu/fresh g, respectively). Also, DM digestibility was increased for at least 0.25% LST (71.1) and 1% PRP (71.4) compared with untreated hay (69.3%). As a consequence, both LST and PRP increased total VFA with doses as low as 0.25% compared with the untreated hay (93.6 and 95.1 vs 83.3 mM, respectively). In summary lignosulfonates initially tested did not improve the preservation of nutrients in high moisture legume silage but an optimized lignosulfonate showed promise as a low-cost preservative for high moisture legume hay.

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