Document Type : Research Articles
Author
Department of Animal Science, Faculty of Agriculture, Lorestan University, Lorestan, Iran
Abstract
Introduction: The climatic conditions of Iran in terms of lack of water resources and the high water demand of most of the common fodder plants have caused the production of quality fodder in the country to face serious restrictions. Therefore, it is very important to find and optimally use new fodder sources to feed ruminants in order to reduce environmental pollution. One of the new sources of fodder that may have a favorable nutritional value are plants of the Paulowniaceae family in China and East Asia. Several types of paulownia are known in the world. These plants are known for their high growth rate and intense photosynthesis, which are specific to C4 plants, and with wide leaves with a diameter of about 90 cm. The trunks of these trees are used in the wood industry, so the commercial production of Paulownia wood produces a large mass of leaves, which are usually used as natural fertilizers. At the age of about 6 to 8 years, the production leaf of each Paulownia tree reaches about 100 kg. When the leaves have a favorable nutritional value, they can be used as fodder in feeding ruminants. Paulownia leaves contain phenolic compounds, especially phenolic, saponin and flavonoid acids, which may modulate rumen fermentation and produce beneficial effects such as improving nitrogen metabolism and microbial protein synthesis, as well as reducing methane gas production in the rumen.In Iran, there has been no study on the nutritional value of paulownia leaves for use in animal feed. Therefore, the aim of this research was to investigate the chemical composition of paulownia leaves and then to investigate the nutritional value, parameters of gas production, digestion and fermentation characteristics of silage resulting from the mixture of different levels of Tebjoo hybrid variety of paulownia leaves with fodder corn in vitro.
Material and Methods: The required amount of corn forage and paulownia leaves (Tebjoo hybrid variety) was prepared and transferred to the laboratory. At first, the chemical composition of corn gorage and Paulonia leaf samples was immediately determined based on conventional methods. Then, both forages were chopped into 2-4 cm sizes using a hand chopper for silage. The experimental silages were consisted of substituting Paulownia leaves for forage corn at level 0 (corn silage only), 25, 50, 75 and 100% of Paulownia leaves, respectively. The silage operation of the treatments was done in plastic containers and the silage period lasted 60 days. Determining the chemical composition of fresh fodders and the nutritional value of experimental silages including chemical composition, in vitro gas production and fermentation parameters, nutrient digestibility and enzyme activity were carried out based on a completely random design.
Results and Discussion: Results indicated that dry matter (DM), organic matter (OM), crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), ether extract (EE), lignin, non-fibrer carbohydrates (NFC) and water soluble carbohydrates content of fresh paulownia leaves were 266, 911, 173, 402, 201, 35.5, 86.4, 404 and 91.2 g/kg DM, respectively. The mentioned chemical composition in paulownia silage were 273, 902, 164, 393, 191, 38.8, 74.5, 386 and 25.4 g/kg DM, respectively. With increasing substitution of paulownia leaf silage instead of corn silage, DM, CP, lignin, EE, NFC and ammonia nitrogen concentration increased linearly (P<0.05). However, OM, NDF and ADF decreased linearly (P<0.05). By increasing the replacement level of paulownia leaf instead of corn silage up to the full replacement level, in vitro gas production (GP) in 24, 36 and 48 hours, GP potential (coefficient b) and short-chain volatile fatty acids concentration decreased linearly (P<0.05), although it linearly increased ammonia nitrogen concentration and microbial protein synthesis (P<0.05). The activity of carboxymethyl cellulase and filter paper degrading activity decreased linearly by increasing the inclusion of paulownia leaf instead of corn silage up to the full replacement level (P<0.05). However, ruminal alpha-amylase and protease activity showed a linear increase (P<0.05).
Conclusion: The present study showed that the paulownia leaf of hybrid variety of Tebjoo has a favorable nutritional value as a new forage source in animal nutrition. Also, the preparation of experimental silages by including different levels of paulownia leaves instead of corn silage increased crude protein and water soluble carbohydrates contents in the silage, which is recommended for animal feeding in the conditions of significant shortage of protein resources in the country. However, it seems necessary to carry out more in vivo studies to confirm the results of this research.
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