Effects of Different Levels of Dietary Fish Oil and Poultry Fat on Performance
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.
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 tobe 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 1×1×0/8 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 tobe 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. The composition and calculated nutrient composition of the treatment diet is shown in Table 1.
Table 1: Composition and calculated nutrient content of diets fed to chicks
Ingredients and Composition, % Starter diet 1 Experimental Withdrawal
diet Plan diet 2
Yellow corn 62.50 61.50 55.50
Wheat – – 20.00
Soybean meal 30.50 31.00 20.10
Fish meal 4.00 1.00 1.55
Added fat/oil 3/ PF/ FO – 3.00 –
Monocalcium phosphate 0.80 – –
Dicalcium phosphate – 0.90 –
Bone meal – – 0.80
Oyster shell 1.20 1.40 1.00
DL-Methionine 0.30 0.20 0.07
Salt 0.20 0.30 0.23
Vitamin/mineral premix4 0.45 0.45 0.45
Coccidiostat 0.05 0.10 0.10
Vit E – 0.10 0.10
Vit A 0.10 0.05 0.10
Total 100.00 100.00 100.00
Calculated nutrient content
ME (kcal/kg) 2,950 3,136 3,020
Crude protein (%) 21.20 19.50 17.11
Calcium (%) 0.32 0.14 0.15
Available P (%) 0.32 0.21 0.23
Methionine (%) 0.37 0.31 0.28
Methionine+cystine (%) 0.65 0.56 0.52
Lysine (%) 1.22 1.07 0.90
1starter diet fed to birds from 0 to 21 d.
2oil remove for one wk before slaughter (to decreased of unacceptable odors)
3three percent added fat: T1, control diet = 3% poultry fat (PF); T2 = 1% fish oil (FO) + 2% PF; T3 = 2% FO + 1% PF; T4 = 3% FO
4provides per kilogram of diet: vitamin A, 9,000,000 IU; vitamin D3, 2,000,000 IU; vitamin B1, 1,800 mg; vitamin B2, 6,600 mg; vitamin B3, 10,000 mg; vitamin B6, 3,000 mg; vitamin B12,15 mg; vitamin E, 18,000 mg; vitamin K3, 2,000 mg; vitamin B9, 1,000 mg; vitamin B5, 30,000 mg; vitamin H2, 100 mg; folic acid, 21 mg; nicotinic acid, 65 mg; biotin, 14 mg; choline chloride, 500,000 mg; Mn, 100,000 mg; Zn, 85,000 mg; Fe, 50,000 mg; Cu, 10,000 mg; I, 1,000 mg; Se, 200 mg;
A GC apparatus consisting of a Dany GC-1000 (Italy), equipped with FID detector, data processor (DS-1000, Dany), hydrogen generator model GLAIND-2200 (Italy) and a split/split less injector was used. Separations of fatty acids were performed on An Altech Econo-Cap, EC-1000 capillary column (30 m×0.25 mm i.d., film thickness 0.25 μm).
Methanol, n-heptan, diethylether and other chemicals were all from E. Merk (Germany). Fatty acid standards mix was purchased from supelco co. High pure helium (99.999%) was from Roham Gas Co. (Midde East Dubai, United Arab Emirates).
The total lipid fraction was extracted according to Folch et al. method . For determination of fatty acids about 500 mg of the samples were freeze-dried and extracted with chloroform-methanol mixture (2:1). After vaporization of solvent derivatization reaction was carried out on residue by adding 1 ml of potassium hydroxide 2 M in pure methanol and then shacked for 1 h at room temperature (25±1˚C). The methyl esters were extracted in 3×0.5 ml n-heptan and 1 µL was injected to GC.
The initial column temperature was maintained at 75 ˚C for 1 min and then raised at 30 ˚C / min to 182 ˚C and held for 8 minute and temperature was then increased at 7.5 ˚C / min to 200 ˚C and held 1 min. Helium was used as carrier and makeup gas, which their flow rates are 1.2 ml/min and 25 ml/min respectively. The injector and detector temperature were held at 250 ˚C and 260 ˚C respectively. Injections of samples were made in split less mode.
The experiment was based on a completely randomized design. The experimental unit being the pen average for each performance variable. The data were analyzed by means of one-way ANOVA. When analysis of variance indicated a significant treatment the means were compared by multiple range tests. Significance was accepted at the 5% confidence level. The data are expressed as means and their standard errors (SE).
RESULTS and DISCUSSION
Fatty acid composition of supplemental fats
The fatty acid profiles of the test oil and fat show that the poultry fat (animal origin) used in this study are rich in linoleic acid, C18:2n-6 and fish oil (Marin origin) have high concentrations of linolenic acid (LNA, C18:3n-3) and long-chain n-3 PUFA naming eicosapentaenoic acids (EPA, C20:5n-3), docosapentaenoic acid (DPA, C22:5n-3) and docosahexaenoic acid (DHA, C22:6n-3) (Table2). These data are consistent with those obtained in other studies (Phetteplace and Watkins, 1990; Olomu and Baracosa, 1991; and Manilla et al, 1999). Since the fatty acid composition of broiler chicken carcass may be influenced considerably by that of the diet (Miller and Robish, 1969; Hargis and Elswyk, 1993), it is expected that diets containing oils and fat of different origin will influence carcass fatty acid composition, reflecting their predominant fatty acids. On the other hand, The PUFA content was also obtained from direct deposit from dietary fat and, to a much lesser extent, from de novo synthesis through elongation and desaturation from the other groups as reported by Lopez-Ferrer et al (2001).
Table 2. Fatty acid composition of added fat/oil to growth diet
Fatty acid3 poultry oil fish oil
Percentage of total fatty acids
C14:0 4.43 7.33
C16:0 25.08 19.61
C16:1n7 Trans 5.31 7.76
C18:0 8.36 5.36
C18:1n9 26.84 18.95
C18:1n7 8.01 0.17
C18:2n6cis 17.70 3.41
C18:3n3 1.70 9.93
C20:1n9 0.20 0.45
C20:4n6 0.40 0.79
C20:5n3 0.00 11.50
C24:0 0.00 3.46
C22:5n3 0.00 2.21
C22:6n3 0.00 8.30
Others 1.97 2.77
Total SAT 37.87 35.76
Total MUFA 40.36 27.33
Total PUFA 19.80 34.14
Total n6 18.10 4.20
Total n3 1.70 29.94
1Values are means of two determinations
2SAT = saturated; MUFA =monounsaturated fatty acid; PUFA=poly-
Unsaturated fatty acid
3Others fatty acids that no detected
Influence of the experimental diets on live weight, growth rate, feed intake and feed conversion ratio (FCR) in the broiler chickens
The all of performance parameters showed significant difference with the exception of the feed intake. With the increase of FO contains and decrease of PF levels, improved feed efficiency, weight gain and final weight in male broiler chickens (P<0.01). This resulting for T2, T3 and T4 were better that those for T1 (Table 3). The effect of type of fat on efficiency feed could be related to degree of unsaturation, because some outers (Alao and Balnave, 1985; Pinchasov and Nir, 1992; Zolisch et al, 1997) have reported that digestibility of fat increases as the degree of unsaturation increases. The inclusion of fish oil in poultry diets has also been reported to have no effect on consumption of feed (Huang et al, 1990) significantly higher weight gain, final weight and significant improvement in FCR (Farell, 1995) was observed in the chickens fed added dietary fat contain 1%PF+2%FO (T3) compared to other three fat sources (3%PF, 2%PF+1%FO and 3%FO). This is in agreement with the findings of Huang et al (1990), Newman et al (1998), Crespo et al (2001, 2002) and Lopez Ferrer et al (1991, 2001). Fish oil rich in n-3 fatty acids reduce the catabolic response induced by immune stimulation and effectively may promote growth (Chin et al, 1994). Table 3: Performance parameters1of chicks according to different amounts of fish oil in diets (21 to 42 d) Experimental diets 2 Variable T1 T2 T3 T4 SE P 3 Live weight (g/bird) 1.92 d 1.97 c 2.05 a 2.02 b 0.577 ** Feed intake (g/bird) 122.67 122.80 122.88 122.83 0.191 NS Weight gain (g/bird) 61.22 d 63.45 c 66.82 a 65.65 b 0.217 ** FCR (g: g) 1.97 a 1.93 b 1.84 d 1.87 c 0.006 ** a, b Values in the same row and variable with no common superscript differ significantly (P 0.05; *= P<0.05; **= P<0.01 Influence of dietary fats on tissue fatty acid composition The fatty acid composition of the broiler carcass lipids is generally a reflection of the fatty acid profile of the diet fed (Tables 4a and 4b). This is consistent with the results of a number of earlier studies (Yau et al., 1991; Zolisch et al, 1997; Ochrimenko et al., 1997 and Lopez-Ferrer et al., 2001). The lipids of the breast muscle in chickens fed fish oil diet showed significant increases in the concentration of total PUFA. However, the relative proportion of the n-6 FA, mainly as LA, C18:2 n-6, increased in breast tissue (P<0.01) when PF was replaced by FO, while had higher concentrations in poultry fat than dietary fish oil. Because High levels of n-3 LC-PUFA might have decreased the desaturation and elongation of LA to its derivatives, as reported by Be´zard et al (1994) in mammals. On the contrast, the chickens fed diets contain fish oil, rich in linolenic acid (C18:3n-3), showed higher C18:3n-3 deposition in tissue investigated. The diets contaning of fish oil, rich in long-chain n-3 PUFA (eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA) and docosahexaenoic acid (DHA) resulted in deposition of these fatty acids in chicken breast (Table 4b). Differences in all n-3 LC-PUFA contents in chicken meat between T2 and T3 were minimal which included FO at 1 and 2% of the dietary fat (3%). However, the proportion of the LC n-3 depot was much higher when Diet 4, with 3 % FO, was given throughout experiment (T4). The PUFA content was also obtained from direct deposit from dietary fat and, to a much lesser extent, from denovo synthesis through elongation and desaturation from the other groups as reported by Lopez-Ferrer et al.(2001). EPA, DPA, and DHA content in tissues were more dependent on their dietary content than on conversion from their precursor. Their presence in tissues at high levels can be considered a marker of the use of fish products in formulated diets. The n-6: n-3 ratio of chicken tissue decreased with altering of substituting PF by FO. The mixture of FO plus PF (T2 and T3) is best fat levels than other treatments. Optimal EPA, DPA, and DHA levels and n-6: n-3 ratio is achieved. The saturated (SAT) and monounsaturated fatty acids (MUFA) content of breast decreased when PF was replaced by FO in 3% dietary fat that the predominant SAT being palmitic acid (C16:0) and stearic acid (C18:0) and the predominant MUFA being oleic acid (C18:1 n-9) . This is in agreement with the findings of Yau et al. (1991) and Scaife et al. (1994). This effect could be due to the dual origin of oleic acid in meat (direct depot from diet and de novo synthesis in liver and tissue). The high palmitic acid (C16:0) content in T1 could account for the high level of oleic acid in meat, through elongation and desaturation (Lopez ferrer et al., 2001). Table 5. Saturated and monounsaturated fatty acid composition of breast muscle lipids of chickens as influenced by experimental diets Experimental diets 2 Fatty acid3 T1 T2 T3 T4 SE P 4 (% of total methyl esters of fatty acids) C14:0 2.02c 2.72bc 3.32ba 4.05a 0.24 *** C16:0 15.65a 12.80b 12.53b 12.45b 0.37 *** C18:0 16.39a 14.92a 10.21b¬ 10.12b 1.06 ** C24:0 1.09d 3.18b 2.65c 4.13a 0.03 *** Total SAT 34.41a 33.63ba 28.63c 30.86bc 1.00 ** C16:1n7 trans 0.60b 0.46b 1.91a 0.70b 0.13 *** C18:1n9 32.67a 29.18b 20.70c 27.81b 0.60 *** C18:1n7 2.22a 0.93b 0.83b 1.17b 0.10 *** C20:1n9 0.57d 0.57d 0.75c 6.06a 0.02 *** Total MUFA 36.07a 31.73b 24.21d 29.69c 0.62 *** a,b Values in the same row and variable with no common superscript differ significantly . 1 Values are means of eight observations per treatment and their standard errors. 2 T1 = diet with 3% poultry fat (PF); T2 = diet with 2% PF+ 1% fish oil (FO); T3 = diet with 1% PF + 2% FO and T4 = diet with 3% FO 3 SAT = saturated; MUFA monounsaturated fatty acid 4**= P<0.01; ***= P<0.001 Table 5. N-6 and n-3 PUFA composition of breast muscle lipids of chickens as influenced by experimental diets Experimental diets 2 Fatty acid3 T1 T2 T3 T4 SE P 4 (% of total methyl esters of fatty acids) C18:2n6cis 2.76c 1.86d 4.92b 12.15a 0.24 *** C20:4n6 1.59b 1.76a 1.80a 1.21c 0.03 *** Total n6 4.35d 6.68c 8.66b 13.36a 0.26 *** C18:3n3 1.59b 0.70c 2.17a 2.40a 0.11 *** C20:5n3 1.04d 5.84c 8.53b 10.54a 0.04 *** C22:5n3 0.15d 0.10b 0.20a 0.29a 0.02 *** C22:6n3 0.15d 0.66c 2.39b 3.80a 0.15 *** Total n3 3.79d 12.41c 16.27b 20.04a 0.21 *** Total PUFA 8.14d 8.14d 24.85b 33.16a 0.42 *** n6: n3 1.14a 0.53c 0.53c 0.66b 0.02 *** a,b Values in the same row and variable with no common superscript differ significantly . 1 Values are means of eight observations per treatment and their standard errors. 2 T1 = diet with 3% poultry fat (PF); T2 = diet with 2% PF+ 1% fish oil (FO); T3 = diet with 1% PF + 2% FO and T4 = diet with 3% FO 3 PUFA= polyunsaturated fatty acid 4***= P<0.001, 5ND=No detected 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 . 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