Document Type : Research Paper
Authors
1 Department of Animal Science, Faculty of Agriculture, Razi University, Kermanshah, Iran.
2 Department of Animal Science, Razi University, Kermanshah, Iran.
3 گروه علوم دامی، دانشکده کشاورزی، دانشگاه رازی، کرمانشاه، ایران.
Abstract
Introduction: Ensilage is one of the methods of preserving forage plants for livestock feeding. The use of carbohydrate sources to prepare of silage improve the quality of fermentation by producing high lactic acid concentrations. The aerobic stability of silage after exposure to air is one of the quality parameters of silages. Heterofermentative lactic acid bacteria are among the additives that have been used to improve the aerobic stability of silages. However, there is no information on the use of the Lactobacillus fermentum on the aerobic stability of Napier grass silage with or without the use of carbohydrate sources.
Aim of study: This research was conducted to study the effect of Lactobacillus fermentum 92069 and molasses on fermentation properties, aerobic stability and in vitro digestibility of Napier grass silage as a new forage source (introduced for the first time) in the country.
Material and methods: Napier grass was cultivated at experimental station of school of Agriculture, Razi University on May 2021. In order to prepare Napier grass silage, the forage was harvested, chopped and treated with 0, 3 or 6 % molasses with or without 0, 1 × 106 cfu or 2 ×106 cfu of Lactobacillus Fermentum 92069 per gram of fresh forage. Forage was ensiled in laboratory silos with four replicates. After 90 days of ensiling, chemical composition and fermentation products of silages such as lactic acid, butyric acid, acetic acid, ammonia nitrogen and in vitro digestibility were determined. The fungal population of silages including yeast and mold were also determined. During the aerobic fermentation process, aerobic stability of the silages and changes in pH and the population of fungal in the silages were determined.
Results and Discussion: Increasing the level of molasses was associated with an increase in dry matter and soluble carbohydrates of silage. The lowest pH values (3.90 to 3.97) and higher production of lactic acid concentration (47.9 to 53.3 g/kg dry matter) were observed in silages containing the high level of molasses with or without bacterial inoculant. The effect of using Lactobacillus fermentum increased the production of acetic acid, but had no effect on the aerobic stability. There was no difference in the fungi population of silages from different treatments. The digestibility of dry matter and organic matter and also metabolize energy were higher in silages containing molasses with or without bacterial inoculant.
Conclusion: The current research regarding the Napier grass silage prepared with no additive had a relatively good quality. However, the use of molasses led to an improvement in the anaerobic fermentation and digestibility. The aerobic stability of Napier grass silages in spite of an increase in acetic acid was not affected by the addition of the Lactobacillus fermentum up to 2 ×106 cfu/ g fresh forage.
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