تأثیر سطوح مختلف تفاله‌چغندرقند و یونجه خشک به تنهایی و توأمان به عنوان جاذب‌الرطوبت بر خصوصیات کمی و کیفی ذرت سیلوشده

Introduction
Ensiling crops with low dry matter results in low quality silages that produce a lot of effluent during ensiling. So, the high level of moisture of these silages stimulates Clostridium fermentation and creates silage with the smell of butyric acid and low nutritional value, and as a result, its consumption in ruminants is reduced. On the other hand, ensiling plant materials with high humidity produces large amounts of leachate, which is not only difficult to collect, but also contains a large amount of nutrients with high digestibility. The problem of collecting and maintaining sewage has made ranchers and farmers think of ways to prevent sewage production. One of the solutions to reduce wastewater production is addition of moisture absorbent materials, which can be used as an alternative to reduce wastewater. Dry sugar beet pulp is one of the products that is produced in the process of sugar production in the factory (Macdonald et al, 1991 and Woolford et al, 1983), these materials also are supplied in the form of strings, or pellets with or without molasses (Macdonald et al, 1991). Dry alfalfa is one of the widely used feed materials in livestock farms, which is easily available to livestock farms and can be used as a moisture absorbent in corn silage (Ayaz et al, 2013). Therefore, the purpose of this research is to investigate the effect of using different levels of dry sugar beet pulp and alfalfa fodder separately and simultaneously as moisture absorbers on the chemical composition of corn silage, digestion kinetics and laboratory fermentation of corn silage. The population of rumen protozoa and different parts of corn silage protein.
Material and Methods
Fresh corn forage was harvested from the field with 2-3 cm pieces. Laboratory-scale silos were prepared in polyethylene tubes with dimensions of 50 x 11 cm, which were equipped with a rubber cap to close the silo door and a drain valve to exit the effluent. Based on the wet weight of corn fodder, moisture absorbent materials were added to different treatments, dry sugar beet pulp and chopped alfalfa, and the experimental treatments included: 1- corn silage without additives (control), 2- corn silage with 1.25% chopped alfalfa and 3.75% of dry sugar beet pulp 3- corn silage with 2.5% chopped alfalfa fodder and 2.5% dry pomace of sugar beet 4- corn silage with 3.75% chopped alfalfa and 1.25% dry sugar beet pulp, 5- corn silage with 5% chopped alfalfa fodder, 6- corn silage with 7.5% chopped alfalfa forage, 7- corn silage with 5% dry sugar beet pulp, and 8- corn silage was mixed with 7.5% dry sugar beet pulp. Before making silage, the chemical composition of corn fodder, alfalfa and dry sugar beet pulp was measured in the laboratory (Table 1). The amount of corn silage produced in different treatments was measured and recorded.
The experimental silage samples were ground after drying and dry matter, ash, organic matter and crude protein (AOAC, 2002) and NDF and ADF were measured to perform the gas test, dried silage samples were ground using a 1 mm mill. Broderick and Kang's method (Broderick et al, 1980) was used to measure ammonia nitrogen concentration. Ruminal fluid protozoa population count (Dehority 2003) and different protein parts (A, B1, B2, B3 and C) were measured by the method of Listeria et al. (1996). The amount of metabolizable energy and the digestibility of organic matter of the experimental silages were estimated (Menke and Steingass 1988) and the total volatile fatty acids were calculated (Makkar 2010).
Results and Discussions
The effect of adding different levels of chopped dry alfalfa and dried sugar beet pulp on the chemical composition of corn silage is shown in Table 2. The amount of dry matter showed a significant difference between experimental silages (p<0.05). Crude protein content of corn silage containing 7.5% dry alfalfa was higher than other treatments, and corn silage containing 5% dry sugar beet pulp and silage without additives had the lowest crude protein content (p<0.01). By adding moisture absorbing materials (dry sugar beet pulp and chopped dry alfalfa to the corn silage), silage dry matter content increased and the production effluent decreased. In line with the results of the present experiment, increasing the amount of alfalfa forage as a moisture absorber in corn silage increases the amount of crude protein (Moeinizade et al, 2013).
The effect of adding different levels of chopped dry alfalfa and dry sugar beet pulp on gas production parameters, ammonia concentration and the total protozoa population are shown in Table 3. Different levels of dry alfalfa and dry sugar beet pulp did not affect the gas production parameters. Similar to the results of this experiment, it was shown that the addition of dry alfalfa to corn silage compared to corn silage without additives did not affect gas production and its rate (Ozturk et al, 2006). Ammonia concentration and total population of protozoa were not affected by the type and amount of moisture absorbent material. One of the factors affecting rumen ammonia concentration is the rate of decomposition of protein source. The higher the degradability of the protein source used, the correspondingly higher rumen ammonia concentration (Lima et al, 2010). It has been shown that adding wheat straw to corn silage had no effect on rumen ammonia nitrogen content (Alsahmi 2008).
Table 3 shows that estimated metabolizable energy, total volatile fatty acids and organic matter digestibility were not significantly different. It was shown in a study (Ozturk et al, 2006) that by adding alfalfa to corn silage, there was no difference in its dry matter digestibility compared to silage without additives (without moisture absorbent) and with increasing the ratio of alfalfa in corn silage, the amount of dry matter digestibility and the metabolizable energy of silage increased significantly (p<0.05). These results show that corn silage containing moisture absorbent materials may provide more metabolizable energy to ruminants.
Protein fraction (table 4) were affected by moisture absorbent materials, so that the lowest amount of parts A and B2 related to corn silage contains 7.5% of dry sugar beet pulp, and the highest amount of parts A and B2 related to corn silage It contains 7.5% of chopped alfalfa fodder (p<0.01)., There was no significant difference between B1 part of the protein among the experimental treatments. Corn silage containing 7.5% and 5% of dry sugar beet pulp accounted for the lowest and highest fraction of B3 protein, respectively (p < 0.01), and corn silage without additives and corn silage with 7.5% dry sugar beet pulp, respectively. The least and most part C of the protein were allocated to themselves (p<0.01).
Conclusion
Addition of chopped dry alfalfa and dried sugar beet pulp to corn silage was associated with an increase in silage dry matter and reduced the amount of produced effluent, and in the meantime, corn silage containing 7.5% of dry chopped alfalfa had better results than other silages. Corn silage containing different levels of chopped dry alfalfa and dried sugar beet pulp had different protein fractions, and the difference in these fractions can affect the amount of protein broken down in the rumen and the amount of protein passing to the lower parts of the digestive tract.