Fermentation Acids, Aerobic Fungal Growth, and Intake of Napiergrass Ensiled with Nonfiber Carbohydrates

Effects of brewer's spent yeast inclusion level and ensiling duration on fermentative, fungal load dynamics, and nutritional characteristics of brewer's spent yeast-based silage

Objective

This study was conducted to evaluate the effect of brewer's spent yeast (BSY) inclusion level and ensiling duration (ED) on fermentative, fungal load dynamics, and nutritional characteristics of brewer's spent-yeast based silage.

Materials and methods

To prepare the silages materials, 4 BSY inclusion levels (0, 10, 20, and 30%) to replace BSG and 3 ED (2,4 and 6 weeks) were arranged in 4 × 3 factorial combination using a completely randomized design (CRD) in 5 replications. The ratio of brewery spent grain (BSG) to wheat bran (WB) used majorly as protein and energy sources, respectively was 30:69 with a 1% salt addition. Parameters measured include observation for surface spoilage, yeast and mold colony count, silage temperature, pH, total dry matter loss (TDML), major proximate, detergent fractions and permanganate lignin, in-vitro organic matter digestibility (IVOMD) and estimated metabolizable energy (EME) values.

Results

The study revealed that at any BSY inclusion level and ED, extensive mold growths and discolorations were not observed. However, slightly higher values of 6.5, 5.7, and 12.2 colonies forming unit (CFU)/g DM yeast, mold, and total fungal counts (TFC), respectively were recorded only at the 6 weeks of the fermentation period with 30% BSY inclusion level. Brewer's spent yeast inclusion level and ED had a significant (P < 0.05) effect on silage temperature (mean = 18.05 °C) and pH (mean = 4.16). Among proximate and detergent values, crude protein (mean CP g/kg DM = 204.5), neutral detergent fiber (mean NDF g/kg DM = 552.9), and acid detergent fiber (mean ADF g/kg DM = 115.9) responded significantly (P < 0.05) to both BSY inclusion levels and ED.

Conclusion

Among nutritional quality, CP, IVOMD, and EME of silage samples were subjected to substantial improvements when silage masses were prepared from 20% BSY inclusion levels and when the same silage materials were allowed to ferment for four weeks. In addition, the lab-based experiment should be supported with additional silage quality parameters like volatile fatty acid content of the silage materials and supplementation of ruminant livestock under both on-station and on-farm conditions using either a pilot and/or target animals.

Effects of urea-treated oil palm frond on nutrient composition and in vitro rumen fermentation using goat rumen fluid

Ammoniation of oil palm frond (OPF) with non-protein nitrogen (N) sources has been shown to improve the nutritional value and digestibility of OPF in ruminants. This study evaluated the effect of treating OPF without (control) or with different urea levels (1%-5%) on chemical composition and in vitro gas production, digestibility and fermentation properties using goat rumen fluids. The results showed that the treated OPF with urea (1%-5%) had significantly lower (p < 0.05) dry matter (DM), organic matter (OM) and ash contents than that of the control. The crude protein (CP) content of treated OPF increased (linear p < 0.05; quadratic p < 0.05) with increasing levels of urea inclusion (1%-5%), whereas the contents of neutral detergent fibre (NDF) and acid detergent lignin (ADL) were significantly (p < 0.05) decreased. The CH₄ (ml/500 mg DM incubated) production decreased (linear p < 0.05) with increasing levels of urea inclusion in treated OPF silage. However, in vitro DM and OM degradability were significantly (p < 0.05) increased by higher inclusion levels of urea (4% and 5%). OPF treated with 4% or 5% urea also revealed significantly (p < 0.05) higher total volatile fatty acids and ammonia-N than the control and OPFs treated with 1%-3% urea. Ammoniation of OPF with urea improved its nutritional value and in vitro rumen fermentation profiles in goats. The impact was more pronounced for 4% or 5% urea-treated OPF.

Biotechnological application of sustainable biogas production through dry anaerobic digestion of Napier grass

Napier grass (Pennisetum purpureum), represents an interesting substrate for biogas production. The research project evaluated biogas potential production from dry anaerobic digestion of Napier grass using batch experiment. To enhance the biogas production from ensiled Napier grass, thermal and alkaline pre-treatments were performed in batch mode. Alkali hydrolysis of Napier grass was performed prior to batch dry anaerobic digestion at three different mild concentrations of sodium hydroxide (NaOH). The study results confirmed that NaOH pretreated sample produced high yield of biogas than untreated (raw) and hot water pretreated samples. Napier grass was used as the mono-substrate. The biogas composition of carbon dioxide (30.10%), methane (63.50%) and 5 ppm of H₂S was estimated from the biogas. Therefore, fast-growing, high-yielding and organic matter-enriched of Napier grass was promising energy crop for biogas production.

The effects of additives in napier grass silages on chemical composition, feed intake, nutrient digestibility and rumen fermentation

The effect of silage additives on ensiling characteristics and nutritive value of Napier grass (Pennisetum purpureum) silages was studied. Napier grass silages were made with no additive, fermented juice of epiphytic lactic acid bacteria (FJLB), molasses or cassava meal. The ensiling characteristics were determined by ensiling Napier grass silages in airtight plastic pouches for 2, 4, 7, 14, 21 and 45 d. The effect of Napier grass silages treated with these additives on voluntary feed intake, digestibility, rumen fermentation and microbial rumen fermentation was determined in 4 fistulated cows using 4×4 Latin square design. The pH value of the treated silages rapidly decreased, and reached to the lowest value within 7 d of the start of fermentation, as compared to the control. Lactic acid content of silages treated with FJLB was stable at 14 d of fermentation and constant until 45 d of ensiling. At 45 d of ensiling, neutral detergent fiber (NDF) and acid detergent fiber (ADF) of silage treated with cassava meal were significantly lower (p<0.05) than the others. In the feeding trial, the intake of silage increased (p<0.05) in the cow fed with the treated silage. Among the treatments, dry matter intake was the lowest in the silage treated with cassava meal. The organic matter, crude protein and NDF digestibility of the silage treated with molasses was higher than the silage without additive and the silage treated with FJLB. The rumen parameters: ruminal pH, ammonia-nitrogen (NH₃-N), volatile fatty acid (VFA), blood urea nitrogen (BUN) and bacterial populations were not significantly different among the treatments. In conclusion, these studies confirmed that the applying of molasses improved fermentative quality, feed intake and digestibility of Napier grass.

Acute colic possibly caused by phytobezoar derived from napier grass in 5 Japanese black cows reared in the same farm

For 6 years, 5 Japanese Black cows of the same herd showed anorexia, depression, and dehydration with no feces in the rectum. Biomedical examination of 3 animals showed severe hypokalemia and hypochloremia. Although the first 3 animals died or were slaughtered (causes unknown), necropsy results showed that the cow in case 4 had intestinal obstruction due to phytobezoar derived from napier grass, fed mainly to the cattle as roughage. Therefore, farmers were recommended to avoid the hard root-stem portion of napier grass as roughage. Consequently, less phytobezoar was recovered from the fifth cow, and no similar clinical case of intestinal obstruction was observed thereafter. This is the first report on intestinal obstruction caused by phytobezoars derived from napier grass.

Effects of water-soluble carbohydrate content on silage fermentation of wheat straw

To determine a suitable initial water-soluble carbohydrate (WSC) content to make wheat straw natural fermentation successful and to study fermentation characteristics, glucose was used to adjust the initial WSC content to 1.4%, 4.0%, 5.0%, 6.0%, 7.0%, 8.0%, 9.0%, and 10.0% dry matter (DM) in the wheat straw. At 30 d of fermentation, there were three pHs: when the initial WSC content was 1.4%, the pH was 5.5; when the initial WSC contents were 4.0%, 5.0% and 6.0%, the pHs were near 5.1; and when the initial WSC contents were 7.0%, 8.0%, 9.0% and 10.0%, the pHs were near 4.0. The pattern of changes in WSC content during the fermentation was similar to that in pH. At 30 d of fermentation, there existed a dividing line in WSC remnants between the initial 6.0% WSC treatment and the initial 7.0% WSC treatment. When the initial WSC content was more than 7.0%, the remaining WSC content was more than 23.7 g/kg DM. When the initial WSC content was less than 6.0%, the remaining WSC content was less than 13.6 g/kg DM. Particularly for the 1.4% WSC treatment, the remaining WSC content was 2.1 g/kg DM. The results of the microbiological enumeration showed that with the increase in initial WSC content, the numbers of lactic acid bacteria (LAB) and other bacteria generally decreased. Denaturing gradient gel electrophoresis (DGGE) results showed that when the initial WSC content was beyond 7.0%, the LAB of the fermentation system were detected.

Proteolysis, Fermentation Efficiency, and In Vitro Ruminal Digestion of Peanut Stover Ensiled with Raw or Heated Corn

Peanut stover (PS) is similar to full-bloom alfalfa hay in chemical composition. The objective of this study was to assess the effect of adding raw or heated corn meal to PS at ensiling on silage N components, fermentation acids, and digestion by ruminal microorganisms. The PS was collected after harvesting of peanuts and ensiled immediately without and with addition of raw or heated corn meal (100 g/kg of fresh weight). Corn was added to PS so that the initial mixture would contain adequate dry matter (DM) (approximately 30%) and additional nonfiber carbohydrate to enhance silage fermentation. After 8 wk of silo fermentation, corn-treated silages contained less structural carbohydrates but more non-fiber carbohydrates compared with the untreated control. A shift from hemicellulose to nonfiber carbohydrate use during silage fermentation was evident by corn treatment. Additional corn at ensiling resulted in silage N with less water-soluble N, protein N, nonprotein N, nonprotein nonammonia N (peptides plus amino acids), and ammonia N. Based on changes in soluble nonprotein N before and after ensiling, the amount of proteolysis was approximately 66% for control silage and was nearly 40% lower in response to corn treatment. Adding corn increased silage lactic acid, but both acetic and propionic acids decreased. These changes were reflected in the lower pH and higher fermentation efficiency with corn-treated silages. More DM was digested and greater amounts of volatile fatty acids, except for branched-chain acids, were produced in vitro by ruminal microorganisms with corn-treated silages. In addition, incubations with silage treated with heated corn contained higher concentrations of acetic and propionic acids compared with raw corn. In vitro ammonia accumulation per unit of DM digested was lower for corn treatments than the control, and for heated corn vs. raw corn-treated silage. These results indicate that supplementation of either raw or heated corn on PS at ensiling could minimize proteolysis and improve fermentation efficiency. Advantages from using heated vs. raw corn could extend beyond silage fermentation and include rumen microbial fermentation.