“In this experiment, the effects of different levels of fish oil and poultry fat (FO+PF) on the performance and Breast fatty acids composition of broiler chickens assessed. 3% oil in 4 diets were altered with replacing PF by FO (T1=3%PF, T2=2%PF+1%FO, T3=1%PF+2%FO, and T4=3%FO) and were given ad libitum to the birds throughout the growth period. The performance was calculated at 42 d old and the fatty acid profile were determined after withdrawal of FO from the diet (during one -wk) before slaughtering in 49-d old . Higher live weight, weight gain and lower feed conversion ratio (FCR) were recorded for birds T3 (1%PF+2%FO). High FO concentrations (2 and 3% levels) decreased the saturated (SAT) and monounsaturated FA contents (MUFA) and increased the polyunsaturated FA contents (PUFA) , mainly as linolenic acid and long chain n-3 FA ( C22:6n-3 , C22:5n-3 , C20:5n-3 ) in the breast samples. By replacing the FO diet with the experimental mixture (T2 and T3) and with 3% FO diet (T4), the n-3 and n-6 FA contents increased. However, increase in the amount n-3 FA in compared to n-6 FA contents was doubled in the tissue investigated. Therefore, the n-6: n-3 ratio was decrease to be optimal ratio.
INTRODUCTION
The long chain omega-3 polyunsaturated fatty acids (LC n-3 PUFA) have long been recognized as an important factor in animal feeding. In man and intensively reared animals it appears that diets have become unbalanced in terms of the make-up of fat particularly polyunsaturated fatty acids .The content of omega-3 (n-3) fatty acids has declined and that of omega-6 (n-6)fatty acids increased. By supplementing with fish lipids which are rich in LC n-3 PUFA, the balance can be restored (Bezard et al, 1994; Toncer et al, 1987; Manilla et al, 1999 and Lopez Ferrer et al, 2001).
Fish oil, source of the n-3 fatty acids are supplied as alpha linolenic acid (C18:3 n-3, LNA), eicosapentaenoic acid (C20:5 n-3, EPA) and docosahexaenoic acid (C22:6 n-3, DHA) and poultry fat contain the n-6 fatty acids mainly linoleic acid (C18:2 n-6, LA) and arachidonic acid (C20:4 n-6, AA). With use from fish oil will ensured optimal ratio of n-6: n-3 in diet and increase of effectiveness of linolenic acid. Several studies with diets rich in LNA have failed to control of n-3 and n-6 FA content in chicken tissues (Ajuyah et al, 1993; Scaife et al, 1994 and Lopez Ferrer et al 1991). The use of fish oil (the main source of LC n-3 PUFA) is restricted due to odor constraints in the final product (Hargis and Van Elswyk, 1993).
Thus, this study was conducted to evaluate the effect of use from a composition of oil/fat to be replacing FO with PF to evaluate the effect on broiler carcass fatty acid composition and to determine optimal level of dietary fat to ensure of EPA and DHA amounts and reduce of n-6: n-3 ratio of chicken meat. Their effect on performance was also evaluated.
MATERIALS AND METHODS
Fish oil supplied with collaborator of MEHREGANE KHAZAR (BANDAR ABBAS) company and poultry fat purchased at SEFIDAN MORGE TABRIZE industrial slaughtering unit. This oils stored in dark station at 40c until to mixing with diet.
A total of five handered unsexed one-d-old ROSS chicks were obtained from a commercial hatchery (SAMIN Hatcheries Co., MARAGEH). The chicks were fed a common basal broiler starter diet from 1 to 20 days (starter period). At 21d , 160 male chickens were sexed and randomly resigned to cages of 1 1/8 meters (10 per cage) and fed experimental diets [ diets of containing 3%PF(T1) , 2%PF+1%FO(T2) , 1%PF+2%FO(T3) and 3%FO(T4) ] throughout a 21-d growth period . The experimental diets formulated to be isonitrogenouse (19/5 %CP) and isoenergetic (3136 kcal/kg ME), in accordance with the 1994 recommendations of the National Research Council (NRC). The birds were given access to water and diets ad libitum.
CONCLUSIONS
The results of present experiment indicated that increase of fish oil level in dietary fat resulted in improve of performance in chickens and the n-6 PUFA and n-3 LC PUFA content of breast tissue increased with replacing PF by FO . Of course, increase in amounts of n-3 LC PUFA was almost doubled. But, unlike the n-3 content, the n-6 content in tissues is far more dependent on the n-6: n-3 ratio than on the n-6 FA content in the diet. This n-3 LC-PUFA was almost independent of the n-6 concentration in the diet. Thus, optimal ratio of n-6: n-3 in tissue can only be achieved by adding marine products as fish oil to chicken diets.
Farrell, D.J. (1995) The enrichment of poultry products with the omega (n)-3 polyunsaturated fatty acids: a selected review.
Proceedings of Australia’s Poultry Science Symposium, 1995. 7: 16-21.
Establishing link between omega-3 fatty acids in fish and reduction in coronary heart disease by demonstrating how a diet rich in fish oil lowers blood triglycerides and improves elasticity of large arteries.
The Institute’s research into fish oil began soon after reports emerged of Inuits in Greenland having minimal coronary disease, probably due to their omega-3 rich marine foods.
Initially showing the marked triglyceride lowering effect of fish oil (high blood triglyceride levels are now recognised as a major risk for heart attack), Baker Institute researchers investigated possible mechanisms in clinical studies. They found that fish oil lowered the production of both triglycerides and of the protein apoB, a building block of lipoproteins, which transport fats in the blood (Nestel, P et al. J Clin Invest 1984).
The importance of specific fish oil fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in cardiovascular health were also shown at the Baker Institute. These compounds improve elasticity of large arteries and reduce arterial stiffness — a major factor causing hypertension (Nestel, P et al. Am J Clin Nutr 2002).
On the basis of the recognised health improvements brought about by long-chain omega-3 fatty acids, recommendations have been made to increase their intake, primarily through the consumption of fish, especially oily fish.
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