Recently, there is a great interest about the amount of residue resulted from fish rearing which will have a decisive factor in sustainability of fish farming along the coming years.
With increased concern in environment friendly aquaculture practices, the aquaculture industry has been concentrating on strategies to decrease the environmental impacted wastes from aquaculture facilities.
The major hazardous nitrogen metabolic product in aquaculture is ammonia, constituting about 70% of nitrogenous waste excretion in fish.
Due to harmful impact on fish, ammonia accumulation is of specific concern.
Additionally, nitrite accumulation is considered as an urgent problem which is associated with the recirculating water in the aquaculture system, causing severe physiological alteration leading to fish mortalities.
Effluents from aquaculture need to be treated before discharge into adjacent aquatic ecosystems.
The rate of ammonia is directly associated to the feeding rate, the protein intake and metabolic efficiency.
Dietary protein is the ultimate source of most ammonia in the ponds where fishes are fed.
When nutrient retention and assimilation is low, a great portion of nitrogen is excreted in the aquaculture system which eventually pollutes the environment.
Accordingly, fish diet is affecting water quality through ammonia excretion, which is the principle end product of protein metabolism in aquatic animals.
Hence, a balanced amount of protein in diet can improve growth and reduce ammonia excretion. Yucca Shidigera Extract (YSE) supplementation in fish diet has been proved effective in reduction of ammonia in aquaculture.
Saponin-containing YSE are currently used in the feed industry for control of ammonia and odor. Several possible modes of action were postulated including direct binding of odoriferous compounds (ammonia) to some component of YSE such as saponin, which inhibit microbial fermentation of protein as well as urease inhibition, increased bacterial use of ammonia or by conversion of ammonia to another compound.
A study reveals that yucca causes significant decreased levels of ammonia and nitrite in the aquaria water and increase in nitrate in water. Dietary YSE decrease urea and ammonia levels in the blood and caeca, thus maybe essential for improving the health, by reducing ammonia emission. (1)
Production and accumulation of ammonia in the aquaculture ponds may also be due to other factors like degradation of waste feed and degradation of dead plants and animals, apart from the excretory products of fishes and shrimps. Fishes and shrimps behave lethargic due to the variations in the osmotic pressure.
They are unable to consume food which affects their daily growth. Due to decreased oxygen levels in ponds, shrimps and fishes might suffocate to death. Moreover, an intentional increase in respiration results in a damage to gills, and reduces the ability of blood to transport oxygen. Continued exposure of shrimps and fishes to the sub-lethal concentration of ammonia results in the increased susceptibility to diseases. (1)
Yucca schidigera (Agavaceae), commonly names Yucca, a native plant in arid deserts of American southwest and Mexico, is also in Zhejiang Province, China grown as an ornamental.
Glycol fraction of the extracts from Yucca is found to be effective in binding the free ammonia from surrounding environment. The compound Polyhydroxy stilbene which performs the urease-inhibiting activity, is rich in the bark of Yucca schidigera.
The use of Yucca schidigera extract in aqua farms has shown the excellent results towards the reduction of the ammonia level, improving the water quality and consequently the farm productivity.
(1) BioCURB Dry is a blend of organic molecules and Yucca schidigera extract which binds the preformed ammonia by immediate relieve from the ammonia stress, neutralizes off flavor of ammonia by removing the irritating odor due to ammonia and arrest the further production of ammonia effectively by inhibiting the enzyme urease.
(2) Chicken meat is definitely an important source of dietary protein, and the industry has developed high grade because of intensive farming techniques, comprehensive and balanced feeding, automation equipment and other new technologies. However, diseases in production are problematic especially with the development of antibiotic-resistant bacteria. Therefore, exploring safe, green and efficient additives that increase immunity in broilers has become a research priority.
(3) Steroidal saponins and polyphenols are the main active fractions of YE, they play an important role in it’s application. First of all, saponins can make better environment for digesting and absorbing due to ammonia-inhabiting activity. Secondly, resveratrol, which is found in the Yucca schidigera bark can protect animals from diseases because of it’s antioxidant, antiviral, anti-inflammatory and iNOS expression-inhibiting capability.
Studies show that body weights of birds fed on diet containing 120mg/kg YE were higher than the others, and addition of YE to the diet improved broiler’s average daily gain and feed conversion rate at 42 days of age. Immune cells develop and proliferate in immune organs, and their status determines the level of immune function.
The thymus is a central immune organ that can induce the maturation of T lymphocyte. The spleen is the largest immune organ in birds where immune response occurs. The Bursa of Fabricius is a poultry unique immune organ, which can induce the lymphoid stem cells to mature in the bursa dependent lymphocyte. Supplementation with YE does not result in any discernable effects on weight of these organs but have a trend that low dose can induce while high dose reduces the immune organ indexes.
Saponins can stimulate secretion of cytokines and trigger innate immunity as well as enhance humoral and cellular immune responses. The 100mg/kg YE mainly increases IgG and induced IgM along with the time gone, 200mg treatment brought lower IgA and higher IgM, and 300mg made IgA down.
The results show an adjustment effect of YE on the humoral and cellular immune responses, and 100 or 200mg/kg YE had a positive effect. Methanol extract of Yucca gloriosa roots or Yucca aloifolia leaves exhibit strong radical scavenging activity. These suggest YE supplementation of chicken feed may be beneficial in the antioxidative functions of broiler chickens.
(4)Yucca is recognized as source of sustenance and drug by native Indians due to it’s health-promoting activity and already has possessed GRAS label as food supplements. Yucca powder and juice are available in the market, and their main applications are in animal nutrition, in particular as a feed additive to reduce fecal odors and ammonia, hydrogen sulfide and some other harmful volatile compounds in domestic animal excreta.
(1) Alfaro DM, Silva AVF, Borges SA, Maiorka FA, Vargas S, Santin E. Use of Yucca schidigera extract in broiler diets and its effects on performance results obtained with different coccidiosis control methods. J Appl Poult Res. 2007; 16(2): 248-254
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Dosdata Ruyet J P, Covès D, Duttog Gassete, Le Roux A and Lemarié G (2003), “Effect of Chronic Exposure to Ammonia on Growth, Food Utilization and Metabolism of the European Sea Bass (Dicentrarchus Labrax)”, Aquatic Living Resources,Vol. 16, pp. 509-520
(3) Piacente S, Montoro P, Oleszek W, Pizza C. Yucca schidigera bark: phenolic constituents and antioxidant activity. J Nat Prod. 2004; 67: 882-885.
(4) Kelly AM, Kohler CC. Effects of Yucca schidigera extract on growth, nitrogen retention, ammonia excretion, and toxicity in channel catfish Ictalurus punctatus and hybrid tilapia O. mossambicus × O. niloticus. J World Aquacult Soc. 2003; 34: 156-161
(5) El-Saidy DMS, Gaber MMA. Effect of Yucca schidigera on water quality and growth performance of Nile tilapia (O. niloticus L) fingerlings Egyptian. J Aquat Biol Fisher. 2004; 8: 33-50.