Aquatic macrophytes are highly productive plants, which are characterized by their wide distribution and habitat and to present an accelerated growth, this factor has caused many of the studies on these plants are directed towards its control with emphasis on eradication.
However, in many developing countries with experience in management, this vegetation is utilized as feed for farm animals with the advantage of high productivity that produces bumper crops. Recently, interest in these plants has increased due to its high nutritional value, a fact that favors as an alternative source in animal feed. Another element in its favor is that they have the ability to grow rapidly on nutrient-rich wastewater to produce biomass rich in protein. These plants have been used in diets for ducks, fish and pigs, found a great representation of each of these species spread throughout the world.
Socioeconomic and technological conditions of Third World countries do not allow the development of animal production that is incremental and sustainable if the parameters are set by production models transferred from developed countries, although it is clear that the vast majority of livestock production is closely related to the use of high technology and volumes of grain and protein sources, usually not produced in sufficient quantities and cost in developing countries. Which results in these countries heavily dependent on imports of these products, which under current conditions have become insufficient to maintain production expectations necessary to meet popular demand, prompting the potentiation of feeding traditional alternative.
The tropics offer a number of alternatives for food which we take, for animal production more in line with our conditions, using available resources to maximum environmental bearing in mind that we have a wide variety of plants, show a remarkable growth rate and a high yield per area and provide a quantity of biomass, enough to supply much of the nutritional needs both protein and energy in animal feed (ESTEVES, 2002).
The purpose of any exploitation of cattle is to convert the plant material in a food suitable for human consumption of meat, milk, wool, fur and other products. Waste products of animals such as dung and urine can be used as fertilizer for crops and forages.
Since most aquatic plants is a small value for human consumption, a practical use of this resource is as fodder for livestock. If these are considered in this way then it is appropriate to treat them as a forage crop and is considered best to use them in fresh, dry hay, or forage preserved as well as these silos by analyzing for the type of livestock may be more appropriate and advantage of their use. One disadvantage is that water harvesting as forage for livestock is rarely animals can be fed wing spot this because the water depth, the risks of mud, and pathogens, or water pollution by animals (Little, 1979 .)
Such is the case of aquatic plants that have been considered as an alternative for the production of different species of animal production, for this reason a detailed description of the aquatic macrophytes and their achievements in animal feed.1.1 PIGS
In tropical conditions macrophytes have been used to respond to this production, within these there is a group of plants for their nutritional value as a viable alternative to it. In places where rainfall, irrigation, or freshwater sources are adequate natural or artificial, aquatic plants are highly productive of biomass resources, high protein and fiber an ideal complement to free ration components thereof, as cane juice, honey and tallow, for possible use in pigs (ECG, 2002).
The fish that have been used in feeding pigs with greater impact, mainly Azolladebido growth rate, its relatively easy handling and incorporation into feeding systems for pigs. Among its specific advantages are: High rate of conversion of nitrogen in protein (up to 9 t / ha / year) through its association with the alga Anabaena azollae and amino acid composition very similar to that of the ideal protein. Other aquatic species, with rapid growth and high protein content (up to 40%) Lemna minor, this has been used in diets for piglets replacing some of the protein supplied (ECG, 2002).
These plants are used on farms through recirculation systems matter where you are on a path of purification of waste water from swine facilities, and in turn, constitute a protein source in feed for pigs. Where they are considered plants such as Eichhornia crassipes water hyacinth, duckweed Lemna and Azolla spp spp as protein sources for inclusion in the inventory of tropical protein sources, unconventional, leaf nature. The idea of integrating the use of floating aquatic macrophytes pig farming is particularly attractive, because this way the nitrogen is recycled in this form of production (LY, 1993)
Little is known about the digestive utilization of these plants by pigs, research by LY (1993), indicate that the digestibility in vivo and in vitro protein of the macrophytes is rather low which reported values (%) of 40.2, 36.3, 0; in vivo for Azolla, Lemna, E.crassipes respectively 54.5 and in vitro for Azolla, Lemna 57.2, 41.3 E. crassipes, this due to the high content of cell wall and therefore, crude fiber, this can be a limitation in the use of high levels of leaf floating aquatic sources. Experiments in intact pigs or ileorectostomizados have established the degree of decline in the digestible energy of the diet by increasing crude fiber in it, from the introduction of these macrophytes. Where the answer is rather negative in the water hyacinth, Azolla and moderate, assimilated to the variations found in studies of this interdependence in cereal grains and legumes (LY, 1993).
Water hyacinth can be used in its fresh form, some people prefer to use after it is subjected to a heat process, using machines to slice the plant into small pieces. This plant is high in vitamins (B and C), but high moisture content possible contamination with pathogens causing people not to use the plant in its fresh form for food.
Most farmers prefer 70-80% prior to use cooking with other ingredients like ground corn, rice bran and wheat bran, where the hyacinth is 60 -65% of the volume. It is believed that boiling increases the digestibility of the fiber of this plant, also it acts as a laxative and is especially beneficial for pregnant sows and any animal showing digestion problems (Little, 1979).
Diets containing 0, 10 and 20% of Eichhornia crassipes, sugar molasses type B and soybean meal, respectively, the water hyacinth was from a hog waste pond, which was dried and ground to be included as flour in the diet. Eichhornia meal containing ash, 18.98%, crude fiber, 34.54%, crude protein, 16.45%, gross energy, 16.96 kJ / g dry this diet was offered twice daily to pigs from 45 kg to determine digestibility. Where it was observed that the digestibility of crude protein and organic matter decreased significantly (P <0.001) from 87.0 to 54.8% and from 94.9 to 74.4%, respectively, for treatments with 0 and 20% flour of Eichhornia. By the same token the digestibility of crude fiber decreased significantly (P <0.01) and the daily flow of SCFA and ammonia increased (P <0.001). The digestibility of crude protein and organic matter from water hyacinth meal is very low and its use is not recommended in diets as a means of recycling of N (DOMINGUEZ et al., 1997).
The silage also serves as food for pigs. This is done by cutting the plants and leaving them to wither in the sun for 2 to 3 days, where they are mixed with corn meal and molasses, only to be awaited for a month and a half to two months, the conserved forage through bins used between 15 -25% of the total diet. Where long fed through this system of conservation, showed a greater weight gain (Little, 1979).
Studies in pig feeding rations containing Eichhornia crassipes, whose diets contained 1.54 kg of the ground and boiled and 2.4 kg of concentrate, showed weight gains of 1.54 kg / week, while the other gained 2 kg / week.
On the other hand it was found that crossbred pigs fed a white sludge containing water hyacinth showed a weight gain of 0.48 kg / day and feed conversion of 3.38 (Little, 1979).
Duckweed also has been used in Mexico to feeding pregnant sows and piglets, replacing the protein from soybean meal by 80%, with very good results in production. In Venezuela, fishmeal used in conjunction with Lemna minor and Azolla filiculoides in rations for pigs (Arroyave, 2002).
The addition of sea algae meal has resulted in a decrease in the digestibility of protein, fiber, organic matter, nitrogen-free extract and dry matter and reduce the retention of nitrogen, sea algae should be considered a source of minerals and protein and energy not to feed pigs. The use levels of up to 5% has presented good results, produce higher levels of diarrhea problems (RECHCIGL, 1993).
Tests conducted with crossbred pigs to measure the weight gain in animals fed with Salvinia auriculata and compared with the grass Brachiaria brizanta, each as a supplement to basic rations of rice bran and corn. It was found that the pigs ate less Salvinia (0.76 kg / day) than grass (1.5 kg / day), this low consumption volume is attributed to fresh Salvinia and its palatability. The dry Salvinia pigs were offered but they did not eat at all. For this reason the pigs had less weight gain compared with the pasture. Therefore the authors concluded that the Salvinia auriculata is of little practical value in the feeding of pigs (Little, 1979).
In the municipality of the Guajaro is common the use of Ipomoea aquatic for feeding pigs without any treatment and presumed results are good as far as it is a widespread practice in the area but has not been done to on a technical evaluation of the growth performance and feed conversion.
In the food industry for poultry constantly turn the alarm on new ingredients or new additives that can improve the efficiency of the finished food or who can provide an economy without reducing quality.
In this case the macrophytes constitute a major source of xanthophyll pigments which are found in the carotene content of which are soluble oils found in some plants. There is great diversity of xanthophylls, some of these are very effective in imparting the yellow color of chicken skin and darkening of the egg yolk. Furthermore, the xanthophyll contained in water plants resulted in a good color to stir the yolks; As the xanthophyll contained in yellow maize (Little, 1979).
Although there is little shortage of xanthophyll in the United States, many countries do not have a source of xanthophyll ingredients available, and have a high demand for highly pigmented grills and dark egg yolks, shortages exist in these regular xanthophyll, so aquatic plants are considered as an alternative to inclusion of xanthophylls in animal feeding (Little, 1979).
Small and tender plants such as Lemna and Wolffia are excellent as food for ducks. Lemna minor being rich in nutrients and vitamins. It contains 30 -32% 30-35% albumin and starch. In the liver and egg yolks animals fed duckweed had a volume of vitamins and carotene from 2 to 3 times higher than that of birds (Arroyave, 2002).
In countries like the Philippines water hyacinth is directly supplied to ducks to meet their fiber requirements, this is consumed by the ducks leaving only the hard stems of this plant. Lemna minor has been tried as food for domestic ducks and results in weight gain and egg production were comparable to the usual protein supplement, with the advantage of a 25% reduction in feed costs (Arroyave, 2002).
Aquatic organisms such as fish and shellfish have high protein requirements, therefore, used for feeding the nutrient-rich foods. Fish meal has traditionally been used as the main resource, but its high cost and increased the growing demand for aquaculture, as well as habits of cultivated land, have made efforts be made to find alternative sources of conventional and unconventional protein.
Therefore it is necessary to search for alternative sources of vegetable protein to substitute for fishmeal wholly or partly in aquaculture feed. Therefore the available information focuses on oilseeds, pulses, aquatic plants, other higher plants, algae and microbial proteins such as fungi, bacteria and yeast (Martinez, 1998).
These plants can be used as feed for herbivorous fish or processed into flour to be included as an ingredient in feed, but the feasibility of their use depends on the costs of collection and processing. Macrophytes are distributed globally, being found in almost all environments and are usually considered as pests by interfering with various economic activities, it would be important to use (Appler et al., 1984).
Between fish with high potential for cultivation are grass carp, and some species of tilapia and Puntius javanicus, for which it is estimated that a population of these tents could consume 19.9 tons of aquatic plants to produce 195 kg of fish meat. Depending on the size and age, the fish have preferences for certain types of weeds and therefore its effectiveness will vary to some extent in a fish farm. For its part fry 30 to 50 g feed on aquatic macrophytes such as water lentejilla, but older individuals prefer larger vegetation (PILLAY, 1997).
The addition of 10% flour water hyacinth (Eichhornia crassipes) in diets for channel catfish Ictalurus punctatus resulted in growth above the witness, however, noted that the fish do not eat food with more than 40% of this material, due to the reduction in the palatability of the high fiber content of the lily. Tilapia are better able to use this facility after undergoing the composting process, accepting up to 50% of the material in your diet without affecting growth (Martinez, 1998).
Oreochromis niloticus fed with Azolla pinnata grows well with levels of up to 42% inclusion of this macrophyte meal in diets containing 35% protein. While other research has noted a marked reduction of growth in the same species, replacing animal protein with this fern in diets containing 30% protein. Apparently the differences are related to energy and protein content in diets (Martinez, 1998).
It is considered that the nutritional value of aquatic macrophytes as food is more fresh. Studies by HASSAN AND EDWARDS (1992) found that Lemna is an appropriate supplemental food for herbivorous fish such as tilapia Oreochromis niloticus. Because is used almost exclusively for feeding herbivores. Use problems are the high levels of water they contain and the high costs of extraction. Have been used as food such as flour and fresh. Where it is considered that the fresh form has the highest nutritional value, these products are used regionally and unless there is a low cost industrial process will be difficult to integrate in the list of feed materials.
Lemna, in its fresh state, has been used to replace 50% of conventional protein diet (fish meal and soybean meal) in feed for fish, obtaining encouraging results with respect to survival and height at the end of production cycle. In the same form of presentation has proven to be suitable for the growth of Oreochromis niloticus, both laboratory and earthen ponds in Taiwan. The same was observed for the commercial cultivation of Azolla in Oreochromis mossambicus and Oreochromis hornorum in the state of Morelos, Mexico (Ponce et al., 2004)
When using fresh Lemna sole ingredient in feed for tilapia (monoculture), carp India and China (polyculture), good results were achieved due to decreased handling and the cost of their upbringing, which has shown that fish meet its requirements in the ponds only with this food, even though nutrient concentrations in this state are diluted in fresh plants (Gonzales, 1997).
Found in studies of tilapia production of 3.7 t / ha / year from the fertilization of the water with excreta and 13.4 t / ha / year with the addition of aquatic plants as a food supplement (GARCIA et al ., 2000).
Studies on the growth of hybrid carp to determine the preference and consumption of food which consisted of a combination with six species of aquatic plants, found that most of the species present a predominance of preference on Lemna gibba other aquatic plants.
But studies comparing the growth of hybrid tilapia (Oreochromis niloticus X Oreochromis aureus) cultured in high densities in an experimental recirculating unit and fed with commercial feed and duckweed Lemna gibba, for 89 days with duckweed or a combination of duckweed and commercial pet food. Found that animals fed a combination of commercial feed and Lemna showed better results were observed when fed only with duckweed, the proportion of food was low, obtaining a good conversion (1: 1) and a growth rate Poor relative (0. 67% of body weight daily). When fish are fed a combination of commercial feed plus duckweed, observed that the growth rate of the fish turned to food conversion ratios of 1. 2 and 1. 8. Seventy percent were assimilated mixed diet of converting only 21% of this (Cross, 1994).
In relation to feed costs in intensive tilapia in Africa, these have been halved, but the combination of the diet of fish feed and Lemna gibba considering this aquatic plant can contribute much of the diet of herbivorous fish in Oreochromis hornorum, Oreochromis niloticus, Oreochromis mossambicus, Cyprinus Carpio, finding encouraging results about 20% inclusion in the diet in commercial production systems.
Because of this alternative are considered in the possible inclusion of more than two aquatic plants to compensate for the deficiencies of some nutrients like essential amino acids in which a proper combination, may well increase the quality of the protein (GONZALES, 1997).
According to the chemical composition of aquatic plants are feasible to be used as partial substitutes for protein concentrates as part of the rations of fish and other farm animals, especially when taking into account the high cost of commercial feeds. The use of certain aquatic plants for animal feed will depend on the needs, requirements and quality of these (Gonzales, 1997).
One of the ways is through conservation of forage silage, comparison studies conducted to determine the palatability between the water hyacinth Eichhornia crassipes and grass to grass Panicum purpurascens, which were stored in three silos containing each of the forage and a third a mixture of these two, they were kept for two months this food being tested in cows where it was observed that the animals were reluctant to take the water hyacinth and even after they added salt to it.
However, the mixture of grass to grass with water hyacinth was fed to cows is surprising to see the animals eating the silage. In a second experiment with the water hyacinth and the same silage for 6 days more, observing the animals during the course of this time tasted this food. Presenting an average consumption of grass in ranges of 9.52 to 13.52 kg, an average of 11.52 kg and from a mixture of grass and water hyacinth for silage was 10.10 to 14.53 kg at an average of 12.27 kg and hyacinth silage water was 12.79 to 17.97 kg on average de15.38Kg. These forages stored in silos had a variation in color, kept water hyacinth has a better yellow or amber color. The grass to brown-yellow and the mixture of the two presented an intermediate color between the two (Little, 1979).
Water hyacinth was compared with Pangola (Digitaria decumbens) kept in silos as food for sheep. Pangola and Eichhornia crassipes were Recoil without fade and cut into pieces 1.6 cm tower condensed into a 1.23 mx 2.46 m, being compressed in a press Eichhornia Vincent (1.27 kg/cm2, 42 rpm) to remove moisture. Where were extracted Four kg of dried citrus which were added 5 kg of sugar cane molasses per 100 kg of compressed plant material.
These forages were performed on the respective analysis (% dry matter) where they presented a varied chemical composition observed similar analysis, only the water hyacinth presented higher content of crude protein and ash. The cattle used for this test had a higher preference for Pangola. The digestibility of dry matter, organic matter and crude protein Pangola was higher than that of the hyacinth. It suggests that further research on the conservation of water hyacinth by silo and mineral imbalances especially Ca, P ratios, and high concentrations of K should be corrected suggest researchers (Little, 1979).
Voluntary ingestion of water hyacinth by sheep and cattle was higher in treatments containing 4 kg dry citrus pulp and 1 kg of sugar cane molasses per 100 kg of water hyacinth waste press, these treatments had a high acidity , low ash and less corrosion of the surface both in vivo and in vitro in sheep. The digestibility of grass pangola (Digitaria decumbens) was higher than for kinder treatment of silage hyacinth. The preservation of silage was satisfactory hyacinth formic acid, propionic, acetic. The acceptability of these treatments for cattle was higher with high lactic acid and low pH, these results indicate a potential value of silage as feed for ruminant animals cut (Little, 1979).
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