Ácido linoléico conjugado em dietas para Tilápia-do-Nilo (Oreochromis niloticus) e pacu (Piaractus mesopotamicus)

Abstract

Four experiments were carried out to evaluate the deposition and the dietary conjugated linoleic (CLA) in Nile tilapia (Oreochromis niloticus) and ?pacu? (Piaractus mesopotamicus). In the experiment 1, a total of fifty six Nile tilapias (121.08 ± 8.48 g) were used and fed with commercial extruded diet (28% of crude protein and 3000 kcal of digestible energy) supplemented with 1.2% of CLA, for 49 days, to determine the CLA deposition in Nile tilapia fillet. In the experiment 2, eighty Nile tilapias (109 ± 10 g) were used and fed with the same commercial diet used in the experiment 1, with soybean oil addition (control) and 1.2% of CLA, during 90 days, to evaluate the CLA addition influence on performance, chemical and fatty acids composition of fillets and liver. In the experiment 3, a total of one hundred thirty five Nile tilapias (263.33 ± 25.03 g) were used and fed with pelleted diet (32% crude protein and 3200 kcal of digestible energy) without and with 0.5 and 1% of CLA, to evaluate the dietary CLA on flesh quality, plasmatic lipidic profile, body and fillets fatty acids profile and performance. In the experiment 4, a hundred and twelve ?pacus? (256.19 ± 24.09 g) were used and fed with the same diet of the experiments 1 and 2, without or with 1.2% of CLA to evaluate the CLA deposition and its influence on performance and whole fish, fillets, and liver fatty acid profile, during 60 days. In the experiment 1, the CLA rate deposition was determined by Gompertz function (y=a . exp{-b . exp[-kt]}). Dietary CLA decreased monounsaturated fatty acids concentration on Nile tilapia fillets and its utilization during 30 days before slaughter is enough to maximum CLA deposition in fillets of Nile tilapia. In the experiment 2, no differences on protein efficiency rate, carcass yield, hepatosomatic index and visceral fat were observed. The dietary CLA improved weight gain, feed intake and feed:gain ratio. xvi There was a protein increasein fillets of tilapia fed with CLA. Fish fed with diets having supplemented with CLA showed an increase in saturated fatty acids composition, reduction in n-6 fatty acids in the fillets and increase in n-3 fatty acids and total polyunsaturated fatty acids composition in the liver. In the experiment 3, there were no effects of dietary CLA on weight gain, feed intake, feed:gain ratio, protein efficiency rate, hepatosomatic index, visceral fat, fillet yield and survival. Dietary CLA resulted in an increase in the whole body protein and in a decrease in the fillet lipid content, compared with the fish fed control diet. Dietary CLA was incorporated into the whole body and fillets at expense of unsaturated fatty acids. An increase of saturates fatty acids, especially 18:0 in whole body and fillet was observed. No effects on liquid holding capacity and fillet texture were observed. The CLA addition decreased the blood total cholesterol and triacylglycerols. In the experiment 4, brokenline analysis indicated that the cis-9, trans-11, trans-10, cis-12 and the total CLA maximum deposition in "pacu" tissue was established at 23, 20 and 21 days, respectively. CLA was deposited in high concentrations in all studied "pacu" tissues. No differences on performance and whole fish, fillet and liver compositions were observed. Dietary inclusion of CLA affected the total percentages of polyunsaturated and monounsaturated fatty acids in whole fish, fillet and liver. It was concluded that dietary CLA can be incorporated in Nile tilapia and "Pacu" tissues as functional food to improve human health.