Benha Vet.Med.J., Vol. 17, No. 1, June. 2006

Effect of different dietary sources of fat on broiler chickens: 3- Meat of broiler fed diet containing thermally oxidized frying oil and human health.

N.A. Khadr ,Dept . of Nutrition and Clinical Nutrition .Fac. of Vet. Med., Benha Univ

Abstract There is an urgent need in nutritional societies to develop products that can lower human dietary cholesterol intake. The experiment was conducted to study the effect of different frying oil on cholesterol levels and meat quality of broilers chickens. The responses of broilers tested in this study were serum cholesterol , triglycerides , tissue cholesterol and thiobarbituric acid reacting substances (TBA) values. A total of 45 day old broiler chicks were randomly distributed into 3 experimental groups and fed a standard broiler diet for 8 d. The chicks were fed from 9th to 52 days of age isocaloric and isonitrogenous diets containing 7.02% of 3 different oil sources raw frying oil, heated frying oil for 8 and 48 h respectively. The thigh meat, liver and adipose tissue were excised from 3 carcasses per treatment and evaluated after freeze storage for oxidative stability and cholesterol content. The thermal treatment of frying oil had specific effect on cholesterol level in serum, livers and adipose tissue and Oxidative stability of broiler meat. The consumption of heated oils interferes physically or biochemically with normal cell functions of broiler chicks resulting in changes in the lipid profiles of broiler. Chicken meat is high in saturated fat and cholesterol and is usually considered unhealthier for human. The meat of broiler fed diets containing thermally treated frying oils especially for 48 h has short period for storages as reflex of vitamin E disturbance. The results of the present study showed that broiler chicks fed diets containing extensively heated frying oils produce unhealthy meat for human.

Introduction

Changes in human diets over past 100 to 150 year, particularly in terms of dietary fat intake and its effect on human health, have become a major interest in nutrition research (45; 32). Epidemiological and scientific evidence has shown a strong Benha Vet.Med.J., Vol. 17, No. 1, June. 2006 relationship between total fat intake and composition and a number of diseases, including coronary heart disease, cancer, diabetes, and depression (39; 23; 31; 27). Over the last century, the amount and proportion of animal fat in human diets has increased in many societies. These increases have been associated with the occurrence of cardiovascular diseases (32; 27). Coronary heart disease and arteriosclerosis are strongly related to the dietary intake of cholesterol and saturated fatty acids. In addition, a strong relationship has been demonstrated between cellular cholesterol concentration and Alzheimer’s disease (36). It is widely acknowledged that there is an urgent need to return to balanced fatty acids in the diet by decreasing intake of cholesterol and saturated fat (12). Chicken meat is low in fat and cholesterol and is usually considered healthier than other protein sources, especially red meats of mammalian origin. Because sufficient amounts of cholesterol can be synthesized endogenously to meet physiological demands, dietary cholesterol is not considered an essential nutrient for adults and children over the age of 2 years. Infants and children younger than 2 years of age may not consume sufficient cholesterol to meet the demand for the developing nervous system. Because hepatic cholesterol production, a deficiency will not develop. On the other hand, high intensity of poultry production requires fast growing strains and concentrated energy ration, so poultry rations are often supplemented with oils. Feeding diets with added fat to poultry can confer several economic advantages by providing increased energy levels at a lower cost and is becoming common practice (33). Fats added to the diet for fast growing broilers are generally rich in polyunsaturated fatty acid (PUFAs) (30). PUFA are prone to oxidation, and their oxidation products are absorbed by the intestine, with deleterious effects (7; 29; 17; 8). Despite this, birds fed discarded frying fats and oils did not show any detrimental effects (34; 5). Nevertheless, meat from slightly growth depressed chickens, resulting from oxidized oil Benha Vet.Med.J., Vol. 17, No. 1, June. 2006 consumption, showed changes in fatty acid composition and decreased α-tocopherol content (43; 11; 25). In addition, birds fed oxidized oils recorded higher susceptibility to oxidation in raw (43; 16; 25) and cooked (16; 25) dark chicken meat. The major problems that face poultry production particularly broiler industry in Kalubia are availability and the cost of feed ingredients. This necessitates looking for cheap local sources of feed stuffs. Industrial by-products that are produced as a result of diverse oil practices represent one of the most important and promising energy rich sources. Fat blends for poultry feeding may be based on waste fat from frying operations or on by-products such as distillation residues from edible oil for human and animal consumption. The consumption of heated oils interferes physically or biochemically with normal cell functions resulting in changes in the lipid profiles of broiler. The objective of this study was to investigate some fundamental chemical and biochemical aspects of thermally treated frying oil at different times and broiler lipid risk factors and its relation to human health. Materials and methods 1. Oils and heat treatment The frying oil is a blend of cottonseed, soybean and sunflower oils, the percentage of which is not advertised. The heat treatment was performed in the laboratory using a large frying pan and the heating was unbroken for two days at about 180 ±10 °C taking the quota of each mixture at its respective time 8 and 48h, Samples of raw or heated oils were taken for analysis. 2. Birds, housing and management The present study was carried out using 45, one – day old commercial Arbor Acres broiler chicks. The chicks were randomly allocated into 3 groups, each of 15 chicks and reared on a deep litter system. Benha Vet.Med.J., Vol. 17, No. 1, June. 2006

The different groups were accommodated in separate pens and maintained under good ventilation and continuous lightening program. Feed and water were offered ad. Libitum and the different groups were fed the experimental basal diets until the age of day 9th. All birds were systematically vaccinated against Newcastle and other needed prophylactic measures.

3. Diets The experimental diet in Table (1) was formulated from corn, soybean meal and broilers concentrate.

Table 1: Composition of the basal diet.

Ingredients Amount % Ground yellow corn 50.10 Soybean meal (solvent-extracted, 44% CP) 30.80 Broiler concentrate (52% CP)* 10.00 Oil** 7.02 Mineral-vitamin premix 1.00 Dicalcium phosphate 0.88 Dl. Methionine 0.10 Coccidiostat. 0.10 Total 100 Calculated energy and chemical components (% or kcal/ kg) *** Crude protein 23% Metabolizable energy 3200 kcal/kg Methionine 0.60% Lysine 1.62% Calcium 1.16% Available phosphorus 0.66% * Broiler concentrate contains CP, 51.98%; CF, 0.07%; EE, 6.76; calcium, 8.66%; available phosphorus, 3.66%; methionine, 1.79%; methionine + cystine, 2.4% lysine, 2.82%; salt, 2% and ME, 3083 kcal/ kg diet. **The oils added were frying oil and heated frying oil at 8 and 48h, for the three groups respectively *** The chemical composition of the basal diet was calculated according to NRC (37). Benha Vet.Med.J., Vol. 17, No. 1, June. 2006

Deficient nutrients were supplemented using DL- methionine, dicalcium phosphate. The energy was augmented by adding oil. The diet was mixed to contain 23% protein and 3200 Kcal, ME/kg and fed allover the experimental period in order to fix one rate of oil addition. Also 1% mineral-vitamin premix was added, in spite of that supplemented in the broiler concentrate to ensure the richness of the diet and to cover the safety margins recommended. For the three experimental groups, three kinds of oils were used: the raw frying oil (korsal) assigned for the first group while the korsal oil was heated for two different periods 8 and 48 h and assigned for the last two experimental groups respectively. The oils were considered to have an energy value of 7500 kcal/kg and added at 7.02% of the diet. 4. Laboratory analysis A- The fatty acid composition of dietary oils was determined by the separation of the methyl esters of the fatty acids using gas chromatography. B- Measurement of serum cholesterol and triglycerides: Blood samples were collected for separation of serum. Total serum cholesterol (mg/dL) was determined by quantitative enzymatic- colorimetric technique (1). C- Extraction of thigh and liver oil: At the end of the trial, birds were slaughtered; thigh meat and liver were removed and frozen immediately at −20°C, then thawed and ground. Total lipids were extracted from thigh meat and liver according to the method of Folch (15) and the lipid content in the form of total lipid and triglycerides was determined. D- Extraction of cholesterol: The cholesterol was extracted from meat and liver (2). E- Determination of lipid deterioration: The carcass fat was sampled from thigh meat, liver and adipose tissue for determination of thiobarbituric acid (TBA) value as an indicator of lipid deterioration. The level of lipid oxidation was determined using the TBA procedure. Benha Vet.Med.J., Vol. 17, No. 1, June. 2006

The results are expressed as milligrams of malonaldehyde (MA) / kg of tissue. This method is used for the determination of the volatile aldehydes which are formed during rancidity of oils employing the reaction of TBA with these aldehydes, forming quantitative colored complex compound. The intensity of this color can be measured photometrically to be a useful guide to the degree of rancidity. The method of Sedlaceck (42) was applied with some little modification. The thiobarbituric acid solution was prepared by weighing 1 g of TBA in 100 ml measuring flask then 50ml distilled water was added and 2 ml of 3 N NaOH .The flask was gently heated in a water bath until the TBA was completely dissolved . After cooling 0.4 ml of HCl 3 N was added and completed to the mark. Five gm of the oil was weighed in a round bottom flask of 500 ml, 50 ml HCl 3 N was added using some little glass balls to regulate boiling. The flask was connected to distillation apparatus using water – bath and volatile oxidation products were condensed and collected in 100 ml cylinder. A stop watch was used to regulate the speed of distillation process to collect 30 ml of the distillate in 6 minutes, 20 ml of distillate was pipetted in a test tube 20 x 200 mm and one ml TBA reagent was added followed by one ml phosphoric acid (conc.).The contents of the tube was thoroughly mixed and then gently heated in a water bath for 35 minutes. Blank experiment was carried under the same conditions and the intensity of the formed red color was measured spectrophotometrically are, 450 nm and established as extinction.

5. Statistical analysis: The data were statistically analyzed according to Armitage (3). Results and discussion 1. Fatty acid profile of dietary oils: The profile of fatty acids is of importance to the quality of the utilized oils and to the absorption of these oils by the bird, and also because it influences the quality of the fat deposited in the broiler carcass. The Benha Vet.Med.J., Vol. 17, No. 1, June. 2006 nutritional effects of biological properties of dietary oils are primarily related to their component fatty acids which are classified into three broad categories: saturated (SFA), monounsaturated (MUFA) and PUFAs. A- Saturated fatty acids (SFA): A comparison between fatty acid contents of different experimental oil treatments are presented in Table (2). The heating of frying oil increased the myrstic, pentadecanoic, palmitic, stearic and arachidic acids by about 6.33, 11.85, 5.81 , 7.92 and 6.83% respectively after heating for 8 h and by 15.15, 4.3, 18.46, 26.04 and 12.31%, respectively after heating for 48 h .This may be attributed to the energy produced by the heating is sufficient to cause double bonds migration in both mono and diethenoid acids to ß-Position followed by oxidative degradation of the ß -position and producing an acid lower by two carbon atoms than the parent acid. There for fatty acids with C18 (C18:1 and C18:2) were converted to C16:0 under heat treatment (13), The heating of frying oil increased saturated fatty acids (SFA) from 22.55 to 24.09 and 27.98% after heating for 8 and 48h respectively. The saturated fat once ingested, it stimulates the liver to produce low density lipoprotein cholesterol (LDL) and produce saturated enriched meat since the poultry have limited ability for conversion of fat quality. On the other side coronary heart disease and arteriosclerosis are strongly related to the dietary intake of saturated fatty acids. B- Monounsaturated fatty acids (MUFA): The heating of frying oil increased the palmitoleic and oleic acids, by about 3.85 and 24.04 % after heating for 8 h respectively and by 149.02 and 24.04 % after heating for 48 h, respectively. The monounsaturated fats are relatively neutral with a small tendency to raise high density lipoprotein (HDL) and lower LDL in the body. C- Polyunsaturated fatty acids (PUFA): There are only two essential oils that are required and they are both PUFA. Linoleic acid was decreased by 21% after thermal treatment for 48h. These Benha Vet.Med.J., Vol. 17, No. 1, June. 2006

results are in agreement with those reported by Artman and Smith (4). However the decrease in the amount of linoleic or linolenic acid with prolonged heating might be interpreted as a result of oxidation. The high reactivity of the methane group adjacent to unsaturated centers in linoleic acid is responsible for the fact that such acids are highly acceptable to oxidation and this acid and its esters oxidize approximately ten times as rapidly as those of oleic acid which lack such group. Since these fats lower both LDL and HDL cholesterol, and since they are so prevalent in the form of raw vegetable oils and margarine spreads. Many experts believe that they are too abundant in our diets. The heating of vegetable oil may decrease this action. Other point of caution about PUFA is that they react easily with oxygen (oxidation) and turn rancid easily as a result of disturbance of vitamin E content in the thermally oxidized oils. Oxidized oils could promote inflammation, cancer, arterial damage, degenerative diseases, and premature aging in human beings D- Ratio between ω6 and ω3: The amount of ω6 EFA and ω3EFA in PUFA varies greatly from food to food. It is now known that the ratio of ω6 to ω3 EFA is a more important indicator of optimum health than the absolute amount of PUFA intake. This is similar to cholesterol, where the ratio of HDL cholesterol and LDL cholesterol to total serum cholesterol is more important than the serum cholesterol level itself as predictor of cardiovascular system health. Table (2): Saturated and unsaturated fatty acids of different experimental oils. Frying oil Frying oil Frying oil Items heated for 8 h. heated for 48 h. Saturated Myrstic acid C14:0 0.79±0.009 0.84±0.009 0.91±0.012 Pentadecanoic C16:0 1.35±0.11 1.51±0.02 1.93±0.02 Palmitic acid C16:0 17.2±0.199 18.2±0.17 21.07±0.50 Stearic acid C18:0 2.65±0.04 2.86±0.05 3.34±0.09 Arachidic acid C20:0 0.65±0.03 0.68±0.02 0.73±0.02 Benha Vet.Med.J., Vol. 17, No. 1, June. 2006

Unsaturated Palmitoleic acid C16:1 0.51±0.01 0.69±0.003 1.27±0.04 Oleic acid C18:1 26.62±0.27 27.41±0.24 33.02±0.04 Linoleic acid C18:2 46.47±0.77 45.04±0.09 36.71±0.38 Linolenic acid C18:3 3.63±0.04 2.21±0.097 1.39±0.02

Fig. (1):Effect of thermal treatment on n-3 and n- 6 fatty acids of frying oil.

50 45 40 35 30 (%) 25 20 15 10 5 0 N-3 n-6 Frying oil Frying oil heated for 8 h. Frying oil heated for 48 h.

The effect of heating of frying oil (Table 2) indicated that n-3 and n-6 are decreased by thermal treatment for 8 and 48 h, leading to production of broiler meat poor in ω3 fatty acids. On the other side the ratio between ω6 to ω3 increased by heat treatments

Table: (3): Effect of thermal treatment on total saturated, monounsaturated, polyunsaturated, ω6 and ω3 of experimental frying oil. Frying oil Frying oil Frying oil heated Items heated for 8 h for 48 h Benha Vet.Med.J., Vol. 17, No. 1, June. 2006

.

Fig (2):Effect of thremal treatrment on SFA , MUFA and PUFA % of the used frying oil.

60

50

40

(%) 30

20

10

0 SFA (%) MUFA (%) PUFA(%) Fatty acids Frying oil Frying oil heated for 8 h. Frying oil heated for 48 h.

Fig. (3):Effect of thermal treatement on ratio between n-6 and n-3 fatty acids of frying oil.

40 35 30 25 20 15 10 5 0 Ratio between n-6 and n-3 Frying oil Frying oil heated for 8 h. Frying oil heated for 48 h.

2. Serum cholesterol The results presented in (Table 4) regarding lipid fractions of broiler blood serum show an increase in serum cholesterol Benha Vet.Med.J., Vol. 17, No. 1, June. 2006 confirming the hypercholesterolemic properties of thermally oxidized oils. The increased cholesterol content of serum due to the increment of saturated fatty acids in broiler diets is presented in (Tables 3 and 4). The thermal treatment increased serum cholesterol by 35.21 and 56.39% after 8 and 48 h heating respectively. The extra cholesterol in broiler blood may be stored in tissues (meat enriched cholesterol) and arteries. The blood vessels became narrow, which is referred to as atherosclerosis. Large deposits of cholesterol can completely block an artery so the blood can’t flow through. If an artery that supplies blood to the heart becomes blocked, a heart attack can occur. Or if an artery that supplies blood to the brain becomes blocked, a stroke can occur. Total cholesterol is the amount of HDL and LDL cholesterol found in the blood. Cholesterol travels through the blood in different types of packages, called lipoproteins. High-density lipoproteins are good for you because they remove cholesterol from the blood stream. Low-density lipoproteins deliver cholesterol to the body. This is why too much LDL cholesterol is bad for the body, while the HDL form is good. Saturated fat, once ingested, it stimulates the liver to produce LDL cholesterol. It is well known that saturated fatty acids especially lauric, myristic and palmatic elevate serum cholesterol. In general favorable serum lipid profile attributed to lower fat intake has been confounded by accompanying reduction in saturated fat intake. Data in Table (4) indicated that the serum cholesterol values were influenced by the concentration of dietary saturated and polyunsaturated fatty acids and the ratio between them. Benha Vet.Med.J., Vol. 17, No. 1, June. 2006

Table: (4) Effect of total saturated and polyunsaturated fatty acids of the experimental oils on serum cholesterol and triglycerides of broiler chicks.

Period of Fat quality serum cholesterol Serum heating (mg\dl) triglycerides (mg\dl)

0 hours SFA =22.5% 118.37±1.298 90.06±1.16 PUFA=50.1% 8 hours SFA =24.09% 160.05±1.755 86.25±1.04 PUFA=47.5% 48 hours SFA =24.09% 185.12±2.030 100.07±1.29 PUFA=47.5%

The present study indicated that poultry meat from birds fed diet containing thermally oxidized oils for 48 h are saturated and cholesterol enrich meats. On the other side, this meat becomes unhealthy for human, since some studies showed a 1%increase in serum cholesterol would increase the risk of death in humans due to coronary heart disease by 2% (38).

Fig. (4):Effect of thermally oxidized oils on serum cholesterol and triglycerides of different broiler chick groups.

200 180 160 140 120 (mg \ Dl) 100 80 60 40 20 0 Cholesterol level (mg \ Dl) Triglycerides level (mg \ Dl) Frying oil Frying oil heated for 8 h. Frying oil heated for 48 h. Benha Vet.Med.J., Vol. 17, No. 1, June. 2006

Generally an elevated plasma cholesterol level is an important risk factor for the development of atherosclerosis in humans and also in animals and birds such as budgerigars, Japanese quails, chickens and rabbits (24; 14; 28; 26; 19; 40; 18; 35; 41and 21).

3 .Tissue and liver lipid profiles Ruminant and poultry meat are important sources of protein and other nutrients in human diet. However, they also contain saturated fat and cholesterol. To lower blood cholesterol level, eat poultry and poultry by products low in saturated fatty acids and cholesterol without the skin. All of thermally oxidized oils contain saturated fat and cause increased concentration of saturated fat and cholesterol in poultry meat (Table 4). Ingestion of saturated fats possesses the ability to raise both LDL and HDL levels. Polyunsaturated fats will lower both, while monounsaturated fats are relatively neutral with a small tendency to raise HDL and lower LDL. This recognition and appreciation suggests that dietary SFA in broiler diet influence cholesterol levels in serum which reflected in concentration of saturation and cholesterol of broiler meat. The broiler chicks fed thermally oxidized oils (heated for 48 hours) recorded higher cholesterol and saturation in its meat since the cholesterol rich foods are usually high in saturated fat. In human because hepatic cholesterol production can provide enough cholesterol to meet demand when dietary intake is inadequate, a deficiency will not develop cholesterol so intakes cholesterol and saturated enriched meat have been associated with elevated blood cholesterol levels particularly when the ratio of polyunsaturated to saturated fat is less than 1.0. A cholesterol-rich diet may down regulate LDL-receptor synthesis as a consequence of hepatic cholesterol accumulation. This effect is more pronounced with high saturated fat intake because the increased amounts of bile reabsorbed by the enterohepatic circulation when fat intake is high will decrease hepatic demand for cholesterol for utilization in synthesis of bile. Benha Vet.Med.J., Vol. 17, No. 1, June. 2006

High saturated fat intake may also interfere with LDL receptor binding of LDL-cholesterol by the effect on membrane fluidity. High cholesterol saturated lipids ingestion has been linked to the increment of coronary diseases, particularly atherosclerosis. It is be considered that in human:(A) the ratio of the unsaturated to saturated fatty acids should be around the permissible limits (0.45) and intakes of n-3 polyunsaturated fatty acids (PUFA) should be increased relative to n-6 PUFA (9), (B) The precursor for the n-3 series is a-linolenic (18:3n-3). Department of Health (9) recommends an increase in the consumption of these n-3 fatty acids to overcome the imbalance in the ratio of n-6:n-3 PUFA in the current diets) compared to primitive man (1:1), (10), According to the previous facts, the meat of broiler fed diets containing thermally treated frying oils especially for 48 h causes disturbances in role of essential fatty acids functions in human because man have not the capacity to synthesis the C20 PUFA, eicosapentaenoic acid (20:5n-3)and, to a lesser extent, docosahexaenoic acid (22:6n-3) from18:3n-3 to meet body requirements.

Fig. (5):Effect of thermally oxidized oils on thigh cholesterol of different broiler chick

10.4 10.2

10 ) l D

\ 9.8

g

m 9.6 ( Fig. (6):Effect of thermally oxidized oils on 9.4 cholesterol9.2 cocentration in adipose tissue of different

9 broiler chick groups. Thigh Frying oil Frying oil heated for 8 h. Frying oil heated for 48 h.

80

78

76 ) l D \ 74 g m ( 72

70

68 Adipose tissue Frying oil Frying oil heated for 8 h. Frying oil heated for 48 h. Benha Vet.Med.J., Vol. 17, No. 1, June. 2006

Fig. (7):Effect of thermally oxidized oils on liver cholesterol concentration of different broiler chick groups.

500 450 400 350

) 300 l D \ 250 g m

( 200 150 100 50 0 Table (5): TotalLiver lipids, triglycerides, cholesterol and TBAS in blood serum, thigh, adipose tissue and liver of different experimental groups. Frying oil Frying oil heated for 8 h. Frying oil heated for 48 h. Benha Vet.Med.J., Vol. 17, No. 1, June. 2006

Items units Raw frying frying oil frying oil oil heated for 8 heated for 48 hr. hr. serum Cholesterol mg\dl 118.37±1.298 160.05±1.755 185.12±2.030 Triglycerides mg\dl 90.06±1.16 86.25±1.04 100.07±1.29 Thigh Total lipid g/100g 10.73±0.91 10.47±0.53 6.64±0.85 Triglycerides g/100g 10.64±0.90 10.38±0.90 9.55±0.84 Cholesterol mg/100g 10.31±0.91 10.31±0.52 9.55±0.84 TBAS mg\Kg* 0.53±0.003 0.59±0.009 0.62±0.015 Adipose tissue Total lipids g/100g 73.53±0.63 72.50±1.21 76.82±2.92 Triglycerides g/100g 72.53±0.62 71.85±1.20 76.17±2.89 Cholesterol mg/100 72.06±0.99 72.70±0.076 78.60±3.28 TBAS mg\Kg* 0.52±0.015 0.57±0.017 0.60±0.026 Liver Total lipids g/100g 5.74±0.12 5.46±0.16 5.60±0.18 Triglycerides g/100g 2.98±0.06 2.86±0.08 2.89±0.1 Cholesterol mg/100 336.93±5.21 341.75±10.93 491.04±27.97 TBAS mg\Kg* 0.85±0.032 0.88±0.023 0.92±0.015

*mg TBA \ kg meat

4. Thiobrabituric acid reacting substances: The expectation of the consumer for meat is that it should be healthy, rich in protein, less saturated fat, more unsaturated fat and have a typical flavor. Currently, dietary recommendations flavor the consumption of less saturated fat (6; 22). In body, fat tends to reflect the fatty acid profile of dietary fat (46). The degree of fat oxidation in meat usually determined by the TBA method, which is a good indicator for rancidity (20). The TBA values obtained from experimental samples in this study (Table 5) were significantly influenced by the heating period of frying oil. A direct relationship was observed between TBAS values and dietary thermally oxidized oils. Benha Vet.Med.J., Vol. 17, No. 1, June. 2006

Birds fed raw frying oil had significantly lower thigh, adipose and liver tissue TBA values and thus greater oxidative stability than samples from birds fed thermally oxidized oils. These TBA values were lower in thigh, adipose tissue and in liver tissues. The duration of the heating oil the elevated the values. This observation points to that there is a relation between oil content of antioxidants and heat treatment. This attributed to feeding diets containing heated oil reduced α - tocopherol concentration as a result of presence of oxidation products in thermally oxidized oil . Sheehy (44) stated that consumption of thermally oxidized sunflower oil by chicks reduces α-tocopherol status and increases susceptibility of tissues to lipid oxidations, so cholesterol, which is present in cellular membranes, is susceptible to oxidative processes initiated by free radicals. Concern about the presence of cholesterol oxidation products (COPs) has increased in recent years. Scientific opinion has linked the presence of these compounds (7-ketocholesterol, 25-hydroxycholesterol, cholestanetriol, etc.) is linked to the development of atherosclerotic lesions.

Fig (8) : Effect of thermally oxidized frying oil on TBA cocentration in thigh ,adipose tissue and liver of different experimental chick groups.

1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 TBA (thigh) TBA (adipose TBA (liver) tissue) Frying oil Frying oil heated for 8 h. Frying oil heated for 48 h. Benha Vet.Med.J., Vol. 17, No. 1, June. 2006

The present finding from these results demonstrated that;

1- The profile of fatty acids of vegetable oil was influenced by thermal treatment. 2- A direct relationship between heating period of the oil and the TBA values in storage meat. 3- .Inclusion of thermally oxidized oils in broiler diets leads to reduction in the oxidative stability of meat as a reflex result of decreasing of α-tocopherol in muscle, adipose and liver tissue. It can be concluded that the use of low quality (oxidized) oils calls for an increase in dietary α- tocopherol in order to counter act the oxidative stress suffered by tissues, meat and meat derivatives. 4- Chronic ingestion of meat of broiler chick fed diet containing oils heated for 48 h produces unhealthy meat for human. 5- Increasing in the SFA content in the diet results in an increase in the degree of saturation of meat and other edible parts, thereby increasing susceptibility to change in PUFA and SFA ratio and lower consumer acceptability. 6- Feeding broiler chick on diet containing highly oxidized oils tends to produce products of high cholesterol content and to be unhealthy meat for human.

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الملخص العربى

تأثير إستخدام مصادر مختلفة من الدهن فى تغذية كتاكيت بدارى التسمين -3 لحوم بدارى التسمين المغذاة على عليقة محتويةعلى زيت مؤكسد حراريا وعلقتها بصحة النسان.

ناصر السيد عبد المطلب خضر قسم التغذية والتغذية الكلينيكية ـ كلية الطب البيطري بمشتهر

أجريت هذه التجربة الغذائية بكلية الطب البيطري بمشتهر وقد صممت هذه التجربة لستبيان تأثيرإستخدام زيت القلى التجارى المغلى لفترة طويلة على نسبة الكولستيرول وعلى جودة لحم بدارى التسمين وذلك من خلل قياس تركيز الكولستيرول والدهون الثلثية فى فى دم بدارى التسمين أثناء التجربة وقياس تركيز حمض الثيوبربتيوريك فى دهن اللحم بعدفترة من التخزين .إستخدم فى هذه التجربة 45 كتكوت ﺁربرإيكر عمر يوم حيث تم تقسيمها إلى ثلث مجموعات تم تسكينها فى ثلث حجرات كل حجرة تحتوى على 15 كتكوت وتم تغذية هذه الكتاكيت لمدة ثمانية أيام على عليقة بادئة تجارية وإبتداء من اليوم التاسع تم تغذية المجموعة الولى على عليقة تحتوى عل زيت قلى غير معامل حراريا والمجموعة الثانية على عليقة تحتوى على زيت قلى معامل حراريا لمدة 8ساعات متصلة(متوسط فترة العمل اليومى فى مصر) والمجموعة الثالثة على عليقة تحتوى على زيت قلى معامل حراريا لمدة 48 ساعة متصلة وقد إستمرت فترة التجربة لمة 52 يوم وتم ذبح ثلث بدارىمن كل مجموعة وأخذ لحم الفخذ وعضو الكبد ودهن البطن وتم تقدير المحتوى الدهنى و إستخلص الزيت منهم بالطرق الكيميائية و إستخدم الزيت المستخلص فى تقدير تركيز الكولسترول والدهون الثلثية وقياس درجة ثبات هذة النسجة ضد الكسدةمن خلل قياس تركيز حمض الثيوبربتيوريك وقد أظهرت النتائج أن إستعمال زيت القلى المعامل حراريا لمدة لتقل عن 8 ساعات في تغذيةكتاكيت بدارى التسمين له تأثير ضار على لحوم هذه البدارى حيث زاد تركيز الكولسترول ونسة الحماض الدهنية المشبعة فى اللحم وقلت درجت ثبات دهن اللحم للكسدة أثناء التخزين خاصة عند إستعمال الزيت المعامل حراريا لمدة 48 ساعة وقد أشارت هذه النتائج إلى ٳنخفاض جودة اللحم صحيا و أصبح تناوله يسبب خطرا على صحة النسان.