عنوان مقاله [English]
Introduction: Feed shortages as well as the allocation of more than 75 percent of the cost of livestock feed, challenge-where in ensuring animal protein needed by society has created accurate estimation of the nutritional value of animal feeds, especially the use of agricultural waste As a new source of food supply, it can be an important step in meeting the needs of livestock and reducing breeding costs (Nikkhah et al, 1990). Potato plant with a cultivated area of more than 22 million hectares in the world and production of 376 million tons is the number one tuber crop (FAO, 2016). At present, a large amount of potato crop is allocated to animal feed worldwide, approximately 35% of the total potato crop is wasted during processing as waste (Agricultural Report, 2009). These wastes add to environmental problems if not consumed properly. Biotransformation of agricultural wastes and wastes compared to other processing methods increases the nutritional value of the compounds and causes the least pollution to humans, livestock and the environment. On the other hand, it costs less than other methods (Nikkhah and Amanloo, 1992). Large amounts of ruminal contents are produced daily as wastes in slaughterhouses (Said et al, 2015) and are considered environmental pollutants. Abouhief, Kraidees et al. (1999) that the high cost of disposing of these wastes requires a revision of slaughterhouse by-product management (Rincon, Bermudez-Hurtado et al. 2010). Reduces (Cherdthong, Wanapat et al. 2014). Protein is one of the most important factors limiting food intake for ruminants (Mapato, Wanapat et al. 2010). Today, various plant sources (oilseed meal), animal sources (meat powder) and seafood (fish meal) and non-protein nitrogen (urea and slow-release urea) are used to provide the protein needed by livestock. Utilization of non-nitrogen sources Protein reduces the cost of feed consumed in animal feed and improves production efficiency in ruminants (Horn, Telford et al. 1979, Herrera-Saldana and Huber 1989, Gado, Mansour et al. 1998, Holden 1999, Wang, Wu et al. . 2010).Nitroza is a slow-release non-protein nitrogen source for ruminants containing 40% nitrogen, equivalent to 250% crude protein. Nitrogen is a compound with a special structure that causes the slow release of ammonia in the rumen. Fiber-digesting bacteria need a constant amount of ammonia throughout the day (equivalent to 10-15 mg / dL) for their proper growth and function. This amount of ammonia ensures the proper nutrition of bacteria that play an important role in fiber digestion. Ammonia imbalances occur in normal diets. The rumen is deficient at significant hours of the day and at other times has an increase in ammonia. Potato waste is the product of inappropriate environmental conditions, inappropriate harvesting, physiological changes, damage by insects and pests, etc. Potato waste is an ideal substrate for biohydrogen products, and during the simple fermentation process by applying rumen fluid (rumen liquor microorganisms) achieved from the slaughterhouse and adding slow-release urea (Nitroza), it can be assumed as a high protein byproduct. This study is investigating the potential of using rumen liquid microorganisms with slow-release non-protein nitrogen source for bioconversion of potato wastes by measuring CP, N-NH3, VFA, pH, digestibility and nutrient composition in the fermentation medium. Material and Methods: Rumen fluid was obtained from the slaughterhouse (400 mL) and added to potato wastes (200 g) along with different levels (1.5, 3, 4.5 gr) of nitrogen from the Nitroza source and incubated for 24 h at 39 ̊C. Data were analyzed in a completely randomized design (CRD).
Results and Discussion: Protein content in experimental treatments was significantly (P<0.05) higher than the control group, and the highest level was related to 3 g Nitrogen level (27.223). In the presence of rumen microorganisms, potato wastes with 1.5 g nitrogen from the Nitroza source had the highest digestibility (81.33) during 24 h incubation (P<0.05). The pH of the fermentation medium of the experimental groups ranged from 4.60 to 7.43 for potato waste along with rumen microorganisms group to the added levels of 4.5 g Nitrogen source respectively (P<0.05). In general, based on the results of the present study, rumen liquid microorganisms along with Nitroza as a non-protein nitrogen source can be used in bio-conversion of potato waste to increase nutritional value and nutrient composition. The results of Swingersren et al. (2007) showed that more than half of the raw potatoes remained non-degradable after 5 hours of incubation with ruminal fluid. In vitro disappearance of dry matter and organic matter of potato, skin lesions were reported to be 85.38% and 88.7% and it is probable that these results are slightly dependent on crude fiber (Horn et al. 1979) and digestion rate is more related to starch (Gado et al. 1998). 1 gram of nitrogen from nitrogen may be related to the supply of sufficient ammonia from Nitroza and increase digestion. The results of the study of the effect of various additives including nitrogen on the disappearance of dry matter using the Holden method are reported in Table 5.
Conclusion: Based on the results, adding different sources of nitrogen had a significant effect on food digestibility (p<0.05). According to the results, it can be said that using ruminal microorganisms for bioconversion of potato waste along with supplementation with different levels of non-protein nitrogen sources, including nitrogen, significantly increased the nutritional value of potato waste, which thus in addition to the use of various sources of non-protein nitrogen, research can be done on agricultural wastes that have no marketability and its disposal to the environment causes many problems, slaughterhouse waste. Which are environmentally polluting and used the resulting substance in the diet of ruminants.