Evaluation of chemical composition and nutritional value of dried rumen fluid by spray drying with various hydrocolloids in vitro

Slaughterhouse rumen fluid contains microbial proteins, volatile fatty acids, microorganisms, vitamins and minerals. Rumen fluid has a very diverse population of bacteria and other microorganisms. Rumen bacteria have a thick bacterial polysaccharide (BPS) coating, so this fluid contains hundreds of bacterial polysaccharide molecules. Rumen fluid activity does not appear to be highly dependent on the diet. Bacterial polysaccharides are potent antigens and remain active even after autoclaving (Muscato et al., 2002). On the other hand, it contains high levels of ammonia and phosphorus, which, when disposed of in slaughterhouses, cause environmental pollution. Its nutrients cause eutrophication when excreted in soil and waterways. It is therefore important to find consistent uses of ruminal fluid (Trit and Schuchardt, 1992). The benefits of recycling these wastes are firstly reducing environmental pollution and secondly producing a feed source for ruminants (Mundal et al., 2013.(Spray drying has recently been used to dry biologically active compounds (Tribizenk et al. 1997). It is a simple, fast, and economical technique for obtaining powder from a solution or a liquid suspension (such as an enzyme suspension) (Bajsic and Kranjsevik 2001). This method is widely used in the pharmaceutical and dairy industries to dry milk, whey, antibiotics, vitamins, and enzymes (DeVos et al. 2010). spray drying changes the liquid to a solid form and causes transport, storage, easy examination, and uniform mixing and distribution in food formulations in small amounts (Tan et al. 2005). Some materials are used in the spray drying method as stabilizers to protect active molecules from heat. These include carbohydrates (such as starch, maltodextrin, and dextrose), gums (gum arabic, acacia gum, alginates, and carginals), proteins (milk proteins, whey, and gelatin) (Aghbashloo et al., 2012), Chitosan (2004). These materials improve stability during the manufacturing and storage process, as well as reducing stress and protein denaturation (Maiori et al. 2005). This study was performed in order that these compounds are biologically active after drying by spray drying, and also ruminal fluid can be converted into an enzyme source.

Slaughterhouse rumen fluid obtained by filtration with 4 hydrocolloids of sodium alginate, guar gum, chitosan and maltodextrin in 1% (volume / weight) ratio was dried by spray drying. The chemical composition of the produced powders including the percentage of dry matter, protein, ether extract, in neutral detergent fibre and non-fibrous carbohydrates were determined. To determine gas production and nutritional parameters, 1 and 2 g of each powder were dissolved in 100 ml of 0.1 M phosphate buffer at pH 6.8 and sprayed on alfalfa grass, wheat straw and silage corn (10). Ml per 5 g of feed) and incubated for 24 hours at 39 ° C. Fresh ruminal fluid and phosphate buffer were selected as positive and negative control groups The method of Monk et al. (1979) was used to measure the amount of gas produced Digestible organic matter, metabolizable energy, short-chain fatty acids, lactation specific energy and total volatile fatty acids were estimated using their own formulas.

The results showed that there was a statistically significant difference between dried rumen fluid with different hydrocolloids and without hydrocolloids in terms of chemical composition (P <0.05). The highest percentage of crude protein was related to dried rumen fluid with 1% maltodextrin. The amount of gas produced from incubation of alfalfa hay with processed ruminal fluid was significant at all times except 24 and 48 hours after incubation (P <0.05). Gas production parameters were significantly different (P <0.05). In the case of wheat straw and corn silage, the amount of gas produced was significant at all times except 6 and 12 o'clock (P <0.05). The highest amounts of digestible organic matter (DOM), metabolizable energy (ME) and specific lactation energy (NEL) were related to wheat straw processed with fresh rumen fluid. The highest values of nutritional parameters were related to corn silage processed with rumen dried with 2% maltodextrin. Changes in gas production kinetics of enzyme-treated feeds have been reported previously. Elghandour et al. (2013) stated that increasing doses of an enzyme preparation from a ruminal bacterium, Ruminococcus flavefaciens, increased gas production from four fibrous feeds at all incubation times. Similarly, rate of gas production in two of the four fibrous feeds increased in response to higher doses of the enzyme preparation. Colombatto et al. (2003) observed higher in vitro ruminal organic matter digestibility for enzyme-treated feeds using an in vitro gas production method. This effect is attributed to the increase in degradation rate achieved via a combined effect of direct enzyme hydrolysis and synergistic action between the endogenous (ruminal) and exogenous enzymes. Wallace et al. (2001) examined the effect of two enzymatic preparations on the fermentation of corn and grass silages using an in vitro ruminal gas production method and reported that the rate of gas production increased at concentrations much higher than the recommended application rates. They also observed the highest correlation between increased gas production and enzyme activities against micro-granular cellulose (Wallace et al., 2001).Nutritional parameters, amount of metabolizable energy, total volatile fatty acids, digestibility of organic matter in silage corn were also significantly affected by dried rumen fluid with different hydrocolloids (P <0.05).

This study showed that dried rumen fluid with different hydrocolloids is biologically active and alive and has the ability to become an enzymatic source. Maltodextrin hydrocolloids are also more successful among hydrocolloids in maintaining protein percentage, gas production, and nutritional parameters. Therefore, slaughter ruminal fluid is of great value.