Animal and Veterinary Sciences, University of Maine, Orono 04469.
School of Biology and Ecology, University of Maine, Orono 04469.
J Dairy Sci. 2020 Jul;103(7):6114-6134. doi: 10.3168/jds.2019-17764. Epub 2020 May 14.
Our objectives were to evaluate technical lignins for their antifungal properties against 3 molds and 1 yeast causing hay spoilage, and their ability to preserve ground high-moisture alfalfa hay nutritive value in vitro. 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 the ADV on yeast were evaluated separately with a RCBD. Sodium lignosulfonate (NaL) and PRP were the only treatments with 100 ± 2.8% inhibition of fungi. In experiment 2, the minimum inhibitory concentration (MIC) for selected lignins and PRP were determined. At pH 4, NaL had the lowest MIC across the molds (20-33.3 mg/mL) and magnesium lignosulfonate (MgL) for the yeast (26.7) among the lignins. However, PRP had MIC values that were several-fold lower across all fungi (1.25-3.33). In experiment 3, a RCBD (5 blocks) with a 3 (ADV; NaL, MgL, and PRP) × 4 (doses: 0, 0.5, 1, and 3% wt/wt fresh basis) factorial arrangement of treatments was used to evaluate the preservative effects of ADV in ground high-moisture alfalfa hay inoculated with a mixture of the fungi previously tested and incubated under aerobic conditions in vitro. After 15 d, relative to untreated hay (14.9), dry matter (DM) losses were lessened by doses as low as 1% for NaL (3.39) and 0.5% for PRP (0.81 ± 0.77%). The mold count was reduced in both NaL at 3% (3.92) and PRP as low as 0.5% (3.94) relative to untreated hay (7.76 ± 0.55 log cfu/fresh g). Consequently, sugars were best preserved by NaL at 3% (10.1) and PRP as low as 0.5% (10.5) versus untreated (7.99 ± 0.283% DM), while keeping neutral detergent fiber values lower in NaL (45.9) and PRP-treated (45.1) hays at the same doses, respectively, relative to untreated (49.7 ± 0.66% DM). Hay DM digestibility was increased by doses as low as 3% for NaL (67.5), 1% MgL (67.0), and 0.5% PRP (68.5) versus untreated hay (61.8 ± 0.77%). The lowest doses increasing neutral detergent fiber digestibility relative to untreated hay (23.3) were 0.5% for MgL and PRP (30.5 and 30.1, respectively) and 1% for NaL (30.7 ± 1.09% DM). Across technical lignins, NaL showed the most promise as a potential hay preservative. However, its effects were limited compared with PRP at equivalent doses. Despite not having an effect on preservation, MgL improved DM digestibility by stimulating neutral detergent fiber digestibility. This study warrants further development of NaL under field conditions.
我们的目标是评估技术木质素的抗真菌特性，以对抗导致干草变质的 3 种霉菌和 1 种酵母，并评估其在体外保存高水分苜蓿干草营养价值的能力。在实验 1 中，8 种技术木质素和丙酸（PRP；阳性对照）以 40mg/mL 的剂量进行测试。该实验采用随机完全区组设计（RCBD，4 次运行）和 3 种霉菌×10 种添加剂（ADV）的因子排列。ADV 对酵母的影响单独用 RCBD 进行评估。木质素磺酸钠（NaL）和 PRP 是唯一对真菌有 100±2.8%抑制作用的处理。在实验 2 中，确定了选定木质素和 PRP 的最小抑菌浓度（MIC）。在 pH4 时，NaL 对所有霉菌的 MIC 值最低（20-33.3mg/mL），而镁木质素磺酸钠（MgL）对酵母的 MIC 值最低（26.7）。然而，PRP 的 MIC 值在所有真菌中都低几个数量级（1.25-3.33）。在实验 3 中，采用 5 个区组（5 个块）的 RCBD，具有 3（ADV；NaL、MgL 和 PRP）×4（剂量：0、0.5、1 和 3%wt/wt 新鲜基础）的处理因子排列，用于评估 ADV 在接种了先前测试过的真菌混合物的高水分苜蓿干草中的保鲜效果，并在有氧条件下进行体外孵育。15d 后，与未处理的干草（14.9）相比，NaL 的剂量低至 1%（3.39）和 PRP 的剂量低至 0.5%（0.81±0.77%），DM 损失减少。NaL 在 3%（3.92）和 PRP 低至 0.5%（3.94）的霉菌计数均低于未处理的干草（7.76±0.55log cfu/fresh g）。因此，与未处理的干草（7.99±0.283%DM）相比，NaL 在 3%（10.1）和 PRP 低至 0.5%（10.5）时保存糖的效果最好，同时在相同剂量下，NaL（45.9）和 PRP 处理（45.1）干草的中性洗涤剂纤维值较低，而未处理的干草（49.7±0.66%DM）则较高。NaL 的剂量低至 3%（67.5）、MgL 的剂量低至 1%（67.0）和 PRP 的剂量低至 0.5%（68.5）时，干草 DM 消化率高于未处理的干草（61.8±0.77%）。与未处理的干草（23.3）相比，使中性洗涤剂纤维消化率增加的最低剂量分别为 0.5%MgL 和 PRP（30.5 和 30.1）以及 1%NaL（30.7±1.09%DM）。在技术木质素中，NaL 作为一种潜在的干草保鲜剂最有前景。然而，与 PRP 相比，在等效剂量下，其效果有限。尽管对保鲜没有影响，但 MgL 通过刺激中性洗涤剂纤维消化率提高了 DM 消化率。本研究有必要在田间条件下进一步开发 NaL。
