Nutritional value of aquatic ferns (Azolla filiculoides Lam. and Salvinia molesta Mitchell) in pigs
2009
Leterme, Pascal | Londoño, Angela M. | Muñoz, Jaime E. | Súarez, Jeimmy | Bedoya, Carlos A. | Souffrant, Wolfgang B. | Buldgen, André
Aquatic ferns (AFs) such as Azolla filiculoides and Salvinia molesta are grown on swine lagoons in the tropics and used to feed pigs. The present work aimed to determine their nutritional value. Azolla samples collected in Colombian pig farms contained from 184 to 317g crude protein/kg DM, 469-620g NDF and 98-145g ash. Those of Salvinia contained from 112 to 169g crude protein/kg DM, 518-629g NDF and 161-232g ash. The content in all macro- and micro-minerals were high and exceeded the pig's requirements expressed per kg diet. The proteins of the two species presented a similar amino acid profile and contained from 47 to 53g lysine/kg protein, 11-17g methionine, 53-55g threonine and 14-15g tryptophan. A digestibility study in 60kg pigs was carried out with diets containing maize, soybean meal, minerals and 0, 125 or 250g AF/kg diet. The weight and length of the digestive organs was also measured. The presence of AF decreased the faecal digestibility of crude protein, NDF and gross energy of the diet (P<0.001). The ileal protein digestibility decreased (P=0.03) with the increase in AF level in the diet. The digestible energy content per kg AF, calculated by difference between the basal diet and that of the diet containing 125g AF/kg was 10.76MJ/kg DM for Azolla and 6.58 MJ/kg DM for Salvinia. AF intake did not affect the gastrointestinal tract, with the exception of an increase in the length and weight of the colon of pigs fed 250g AF/kg diet (P<0.01). In conclusion, Azolla and Salvinia are good sources of minerals and essential amino acids but their interest is limited in pig production by their low digestible energy and protein content.
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