Bacterial and Fungal Microbiota of Guinea Grass Silage Shows Various Levels of Acetic Acid Fermentation

This study aimed to gain insights into the bacterial and fungal microbiota associated with the acetic acid fermentation of tropical grass silage. Direct-cut (DC, 170 g dry matter [DM]/kg) and wilted (WT, 323 g DM/kg) guinea grass were stored in a laboratory silo at moderate (25 °C) and high (40 °C) temperatures. Bacterial and fungal microbiota were assessed at 3 days, 1 month, and 2 months after ensiling. Lactic acid was the primary fermentation product during the initial ensiling period, and a high Lactococcus abundance (19.7–39.7%) was found in DC silage. After two months, the lactic acid content was reduced to a negligible level, and large amounts of acetic acid, butyric acid, and ethanol were found in the DC silage stored at 25 °C. The lactic acid reduction and acetic acid increase were suppressed in the DC silage stored at 40 °C. Increased abundances of Lactobacillus, Clostridium, and Wallemia, as well as decreased abundances of Saitozyma, Papiliotrema, and Sporobolomyces were observed in DC silages from day three to the end of the 2 month period. Wilting suppressed acid production, and lactic and acetic acids were found at similar levels in WT silages, regardless of the temperature and storage period. The abundance of Lactobacillus (1.72–8.64%) was lower in WT than in DC silages. The unclassified Enterobacteriaceae were the most prevalent bacteria in DC (38.1–64.9%) and WT (50.9–76.3%) silages, and their abundance was negatively related to the acetic acid content. Network analysis indicated that Lactobacillus was involved in enhanced acetic acid fermentation in guinea grass silage.

Prevalence of Mycotoxins and Endotoxins in Total Mixed Rations and Different Types of Ensiled Forages for Dairy Cows in Lithuania

In this study, 119 samples of total mixed rations and different types of ensiled forage (maize and grass silage, and haylage) collected in 2019–2020 from dairy farms in Lithuania were analyzed to evaluate the quantitative occurrence of mycotoxins and endotoxins. Samples were analyzed using high-performance liquid chromatography (HPLC) with a fluorescent (FLD) and an ultraviolet detector (UV) of mycotoxins and a detection assay based on the ELISA technology for endotoxins. The study included toxins regulated within the European Union (aflatoxin B1 (AFB1), zearalenone (ZEA), deoxynivalenol (DON) and T-2 toxin) and nonregulated toxins (endotoxins). Mycotoxin analysis showed that 49.58% of the samples out of 119 were positive for AFB1, 52.11% for ZEA and DON, 55.47% for T-2 toxin and 84.04% for endotoxins. In the contaminated samples, the highest mean values of AFB1 and T-2 toxin were determined in the grass silage samples, while ZEA and DON–were determined in the maize silage samples. Maize silage samples had the highest ZEA and DON concentrations, exceeding the EU maximum permissible concentration limits. In the haylage samples, AFB1 mycotoxin exceeded the maximum concentration limits. The highest mean value of endotoxins was determined in the total mixed rations samples. This is the first study to provide information about the concentrations of mycotoxins and endotoxins in total mixed rations and different types of ensiled forages for dairy cows in Lithuania.

Authenticity of Hay Milk vs. Milk from Maize or Grass Silage by Lipid Analysis

Hay milk is a traditional dairy product recently launched on the market. It is protected as “traditional specialty guaranteed” (TSG) and subjected to strict regulations. One of the most important restrictions is that the cow’s feed ration must be free from silage. There is the need for analytical methods that can discriminate milk obtained from a feeding regime including silage. This study proposes two analytical approaches to assess the authenticity of hay milk. Hay milk and milk from cows fed either with maize or grass silage were analyzed by targeted GC-MS for cyclopropane fatty acid (dihydrosterculic acid, DHSA) detection, since this fatty acid is strictly related to the bacterial strains found in silage, and by HPLC-HRMS. The presence of DHSA was correlated to the presence of maize silage in the feed, whereas it was ambiguous with grass silage. HPLC-HRMS analysis resulted in the identification of 14 triacylglycerol biomarkers in milk. With the use of these biomarkers and multivariate statistical analysis, we were able to predict the use of maize and grass silage in the cow’s diet with 100% recognition. Our findings suggest that the use of analytical approaches based on HRMS is a viable authentication method for hay milk.

Histidine Promotes the Glucose Synthesis through Activation of the Gluconeogenic Pathway in Bovine Hepatocytes

Histidine (His) is considered to be the first-limiting amino acid (AA) on grass silage-based diets in lactation cows, which correlate positively with lactose yield. The higher glucose requirements of lactating cows can be met through a combination of increased capacity for gluconeogenesis and increased supply of gluconeogenic precursors. However, the effect of His on the expression of gluconeogenic genes in the bovine hepatocytes is less known. Therefore, this study aimed to investigate the regulatory effect of His on the key gluconeogenic genes and glucose output in bovine hepatocytes. The addition of 0.15, 0.6, and 1.2 mM His in a medium significantly enhanced (p < 0.05) the viability of bovine hepatocytes. Remarkably, 1.2 mM His induced profound changes (p < 0.05) in the mRNA level of key genes involved in gluconeogenesis, including PCK1, PCK2, FBP1, and G6PC in vitro. Furthermore, the mRNA expression of PCK1 was significantly elevated (p < 0.05) by the addition of 1.2 mM His at 3, 6, 12, and 24 h of incubation. The hepatic glucose output increased (p < 0.05) linearly with increasing His concentration. These findings indicate that the addition of His may be efficiently converted into glucose via the upregulation of genes related to the gluconeogenic pathway.

Combined Butyric Acid and Methane Production from Grass Silage in a Novel Green Biorefinery Concept

In a Green Biorefinery, grass silage can be a source for lactic acid, proteins, amino acids and fibres. Processing residues can be used for anaerobic digestion and methane production. But by changing the ensiling conditions, butyric acid fermentation can be achieved. That makes grass silage also a potential substrate for a combined butyric acid and methane production. The objective of this study was to determine the potential of butyric acid production at different ensiling conditions applied to grass and measuring the methane yield potential of solid residues after a separation step. The highest butyric acid concentration in the produced press juice was 20.1 ± 4.5 g kg−1 and was achieved by carbonated lime addition and a reduced dry matter content after 90 days at mesophilic storage conditions. This resulted in a theoretical butyric acid yield of 332 kg ha−1 a−1. For the fibrous leftover press cake, a theoretical methane production potential of 2778 m3CH4 ha−1 a−1 was reached. The results show that theoretically a combined production of butyric acid and methane can be realised in a Green Biorefinery concept. Graphic Abstract

Aerobic stability of tifton 85 silage with and without pre-drying in the sun

The objective of this study was to evaluate pH, ammoniacal nitrogen, and aerobic stability of silage of Tifton 85 grass silage with two dry matter contents at different silos opening times. The experimental design was completely randomized, in a subdivided plots scheme, in which the silages constituted the plots and aerobic exposure times the subplots, with four replications. To verify the aerobic stability of the silages, the temperature and pH were analyzed at seven hours after the silos were opened (1, 24, 48, 72, 96, 120, and 144 hours). The pH reached adequate levels for conservation only after 90 days of fermentation for the silages with and without pre-drying in the sun. Ammoniacal nitrogen remained below the recommended limits in both silages. As for the silage temperature, no loss of aerobic stability was observed. However, the observed pH revealed a break instability after 72 hours when the silos were opened at 28 days, with no changes for the remaining silage periods. It is possible to obtain suitable silages from Tifton 85 with or without pre-warming in the sun, however, a minimum fermentation period of 90 days should be adopted. The studied silages presented high aerobic stability, but when kept silage for only 28 days, they should be consumed by the animals within 48 hours after the supply.

Effects of different banana crop residue hays on ensiling BRS capiaçu grass on fermentation profile, aerobic stability and nutritional value of silage

The objective of this study was to evaluate the BRS capiaçu grass silage combined with different hays of banana crop residue on fermentation profile, aerobic stability and nutritional value. The treatments consisted of elephant grass cv. BRS capiaçu (Pennisetum purpureum Schum.) ensiled with 37.44% banana peel hay, 36.06% banana pseudostem hay and 37.00% banana leaf hay, on a dry matter (DM) basis and control silage (no additive). The experimental design used was completely randomized, with five treatments and five replicates. Forage was collected when it reached 3.5 meters in height (90 days). Experimental PVC silos of known weight, 50 cm long, 10 cm diameter, were used for silage making. For all treatments, silage aerobic stability breakdown started after 64 hours exposure to air. The BRS capiaçu grass control silage or silage combined with pseudostem hay (mean of 73.15 kg t GM-1) presented effluent losses 40.46% higher than those observed for BRS capiaçu grass silage + banana leaf hay and 69.17% in relation the BRS capiaçu grass silage + banana peel hay. The inclusion of banana crop residue (hay) when ensiling BRS capiaçu grass decreased 13.93% gas losses compared to the control silage (mean of 3.11% DM). Higher values of total digestible nutrients, metabolizable energy and digestible energy content was found in BRS capiaçu grass silage + with banana peel hay. The greater in vitro dry matter digestibility and in vitro neutral detergent fiber digestibility was observed for BRS capiaçu grass silage combined with pseudostem hay. The inclusion of 37.44% banana peel hay improves the fermentation profile and aerobic stability of BRS capiaçu grass silage.

323 Effect of an Acidogenic Diet with Phytogenic Supplementation on in Situ Degradability of Corn and Wheat Grain, and Grass Silage in Dairy Cows

Modern dairy production systems require larger inputs of energy in diets to increase milk yield. Therefore, dairy cows are at risk of experiencing subacute ruminal acidosis (SARA). The objective of this study was to evaluate grains and forage rumen degradability in cows fed different diets supplemented with a phytogenic (PHY) feed additive. The experiment was conducted with nine rumen-cannulated non-lactating Holstein cows blocked in two groups of four and five animals, and were part of a cross-over design. This study consisted in 2 runs separated by a 12-week washout period, in which cows grazed on pasture. Each experimental run had one week of forage (F) feeding, one week of transition to a high grain (HG) diet, and four weeks of HG (65:35 concentrate to forage ratio in dry matter basis). Cows were supplemented with PHY (a blend of menthol and thymol) or a control carrier (CON) from week F. Corn and wheat grain were ground through a 4 mm screen, while grass silage was ground through a 6 mm screen. Sampling for in situ degradability was performed in F and in week four of HG diet. Data were analyzed with SAS with week of feeding and supplementation as fixed effects and cow as random effect. Corn and wheat 24-h dry matter (DM) and organic matter (OM) degradability increased during HG diet compared with F (P &lt; 0.05), grass silage DM and OM 48-h degradability was reduced by HG diet compared to F (P &lt; 0.01). Additionally, wheat grain 24-h OM degradability was higher for PHY compared to CON under F and HG diet conditions (P = 0.05). Overall, diet composition and SARA conditions can influence grains and fiber degradability in the rumen.