Dietary enrichment of broiler chicken with omega-3 fatty acids and beneficial role in human cardiovascular health: A Review

Broiler meat consumption in the world increases annually with the development of modern diet pattern. Saturated fatty acid content of the meat causes high risk of cardiovascular disease in human. Fish is an important source of omega-3 fatty acids, which reduce the risk of cardiovascular disease in human. However, access to food fish, which are rich in omega-3 fatty acids, is questionable for many people in the world. Fortunately, studies revealed that the dietary enrichment of broiler chicken ration with omega-3 fatty acids enriched the broiler chicken meat with omega-3 fatty acids. Hence, consumption of such broiler chicken meat may supplement the scarcity of consumption of omega-3 fatty acids rich foods viz. fish. Moreover, dietary enrichment of omega-3 fatty acids improves carcass by reducing the abdominal fat deposition in broilers. However, shelf-life of broiler chicken meat that is enriched with omega-3 fatty acid is low due to high levels of lipid oxidation. However, usage of antioxidants improves the shelf-life of omega-3 fatty acid enriched broiler chicken meat.


Introduction
Fig 1. Growth in production of agricultural products in developing countries  Source: FAO (2008). AGRIEAST 2015 (10) P. 27 -35 Broiler meat consumptionin the world increases annually with the development of modern diet pattern. Saturated fatty acid content of the meat causes high risk of cardiovascular disease in human. Fish is an important source of omega-3 fatty acids, which reduce the risk of cardiovascular disease in human. However, access to food fish, which are rich in omega-3 fatty acids, is questionable for many people in the world. Fortunately, studies revealed that the dietary enrichment of broiler chicken ration with omega-3 fatty acids enriched the broiler chicken meat with omega-3 fatty acids. Hence, consumption of such broiler chicken meat may supplement the scarcity of consumption of omega-3 fatty acids rich foods viz. fish. Moreover, dietary enrichment of omega-3 fatty acids improves carcass by reducing the abdominal fat deposition in broilers. However, shelf-life of broiler chicken meat that is enriched with omega-3 fatty acids low due to high levels of lipid oxidation. However, usage of antioxidants improves the shelf-life of omega-3 fatty acid enriched broiler chicken meat.
Animal source foods are complete and nutrientdense, and provide high quality protein and bioavailable micronutrients viz. iron, zinc vitamin A, vitamin B 12 and calcium, particularly for children and pregnant and lactating mothers (FAO, 2011). In particular, consumption of meats prevents anaemia and enhances iron absorption from plant based foods (Walker et al., 2005). Hence, different communities in the world regard meat as a desirable food with high nutritive value (FAO, 1992;Michael and Bambrick, 2005). Irrespective of cultural taboos for the consumption of meats, poultry meat is accepted in many cultures (FAO, 2011), particularly broiler chicken meat (Chashnidel et al., 2010). In developing countries, a great rise in the production of poultry has been observed ( Fig. 1) and expected to continue in future (Speedy, 2003).
On the contrary, meats are the primary source of saturated fats, which are responsible for high risk of cardiovascular disease, diabetes mellitus and cancers in human (McMichael and Bambrick, 2005). Moreover, modern agribusiness and food processing industries change the nutrient content and structure of many food items. For example, hydrogenation of foods changes the double bonds of fatty acid from cis to trans and result with increased trans fatty acids in processed foods. This structural change increases the risk of coronary heart disease (CHD) in human (Simopoulos, 1999). Furthermore, modern diets have high saturated fatty acids (SFAs) and low mono-unsaturated fatty acids (MUFAs) and poly-unsaturated fatty acids (PUFAs) (de Witt et al., 2009). Myristic and palmitic acids are the principal dietary SFAs that increase the blood cholesterol level (Bender, 1992).Arterial plaques, which lead to partial blockage of the blood vessels, are caused by oxidized (rancid) form of cholesterol (Farrell, 2010).
In these contexts, there are growing interests in the world in modifying the cholesterol content and fatty acid compositions of poultry products (Hargis and Van Elswyk, 1993;Sacks, 2002;Salma et al., 2007) to produce superior health quality food. Recent researches also deal with reducing fat, cholesterol, and SFA contents of poultry meat by dietary supplementation of garlic, copper, á-tocopherol acetate and omega-3 fatty acid (Salma et al., 2007). The latter has utmost importance due to its human health benefits. However, consumption of omega-3 fatty acid by human is rare. Hence, there are several studies have been carried out in the world to enrich the favourite human foods viz. poultry meat with omega-3 fatty acids so as to provide health benefits to the human. This article is intended to review the studies related to dietary enrichment of broiler chicken with omega-3 fatty acids and their impacts on productive parameters of broiler chicken and health condition of broiler chicken meat consumers.

Omega-3 fatty acids
Dietary fat consists of both SFA and unsaturated fatty acids (UFA). The latter further divided into MUFA and PUFA. Based on the chemical nature, PUFAs are further classified into omega-3 fatty acids (also called as ù-3 fatty acidsor n-3 fatty acids) and omega-6 fatty acids (Din et al., 2004). Thus, omega-3 fatty acids areone of two families of essential PUFAs. The term omega-3 (also ù"3 or n"3) indicates the first double bond exists as the third carbon-carbon bond from the terminal methyl end of the carbon chain. Eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and alpha-linolenic acid (ALA) are the major omega-3 fatty acids useful for humans.EPA (C20:5 n-3) and DHA (C22:6 n-3) are rich in marine sources viz. fish and shellfish while ALA (C18:3 n-3) is rich in plant sources viz. flaxseed (linseed), soybean, walnut, canola and rapeseed oils (Stone, 1996;Mellor, 2005).
Nevertheless, true essential fatty acids (EFAs) viz. linoleic acid (C18:2 n-6) and ALA (Mellor, 2005) should be converted into EPA and DHA to be effective in human body (Gerster, 1998;Brenna, 2002;AHRQ, 2004). However, the rate of conversion is only around 2% (Mellor, 2005) to 5% (Brenna, 2002) as humans lack the necessary enzymes to convert omega-6 fatty acids to omega-3 fatty acids (Din et al., 2004). Hence, it is very important to have dietary EPA and DHA through meat based diet such as poultry meat, marine and freshwater fish, etc. to get advantages of omega-3 PUFAs.

Fish as a rich dietary source of EPA and DHA
Vegetable oils are rich in ALA, whereas fish and fish oils are rich in EPA and DHA (Sargent, 1997;Din et al., 2004;Mirghelenj et al., 2009). However, amount of EPA and DHA varies among fish species (Table 1) and environmental factors. WHO and NATO recommended 0.3 to 0.5 g/d of EPA+DHA and 0.8 to 1.1 g/d of ALA as a dietary inclusion level of omega-3 fatty acids for a healthy person (Kris-Etherton et al., 2002). Furthermore, American Heart Association (AHA) recommended 1 g/d of EPA+DHA for CHD patients (Kris-Etherton et al., 2002;Schacky and Harris, 2007). Although this level of EPA and DHA could be obtained through fish consumption, the required intake may be difficult to achieve and sustain in long term (Kris-Etherton et al., 2002) due to seasonal availability, affordability and consumer preference of fish (Hargis and Van Elswyk 1993). Hence, supply of these PUFAs is easier if they are incorporated with widely consumed food items viz. meats. In this context, broiler chicken meat is ideal for the enrichment with essential fatty acids.
In poultry, lipid digestion takes place in the small intestine, where the pancreatic lipase breakdowns the triacylglycerols into 2monoacylglycerols and free fatty acids (Nietoand Ros, 2012). These products are formed into micelles when linked to the conjugated bile salts. Monoglycerides and longchain unsaturated fatty acids have higher ability to form the micelles with bile salts than saturated fatty acids due to their characteristic low polarity (Baião and Lara,2005). Because of pancreatic lipase, the mixed micelles are absorbed without any alteration in the composition of fatty acids. Hence, the dietary lipid sources have a direct effect on the fatty acid composition of poultry products (Baião and Lara,2005; Nietoand Ros, 2012).
As the tissues of poultry could simply be enriched with unsaturated fatty acids by increasing their proportion in the diet (Nieto and Ros, 2012), enrichment of broiler chicken meat with omega-3 fatty acids could be an alternative source for fish (Hargis and Van Elswyk 1993 Chickens modify their lipid profile within a week of feeding a new diet enriched with lipid sources (Lopez-Ferrer et al., 2001). Dietary fatty acids could be absorbed and deposited in the body tissue of broiler chickens without any modifications.Thus, lipid composition of broiler chicken meat could be altered according to the fatty acid profile of the dietary lipid sources (de Witt et al., 2009;Hugo et al., 2009b). This ensures the potential to increase the consumption of omega-3 PUFAs through broiler chicken meat (Coetzee and Hoffman, 2002).
Unfortunately, high growth rate of modern broiler chicken breeds has been associated with increased fat deposition. Lipids in broiler chicken are mainly deposited as abdominal fat (20%) and subcutaneous fat (18%), and skeleton fat (15%), fats on liver and feather (2.5%), and fats on carcass (40%) as intermuscular fat, intramuscular fat and subcutaneous fat. Abdominal and subcutaneous fats are the main sources of waste in the slaughterhouse (Tùmová and Teimouri, 2010). However, a minimum quantity of intramuscular fat is necessary for an optimal sensory quality because of its positive influence on succulence, tenderness and flavour (Guo-Bin et al., 2010;Tùmová and Teimouri, 2010;Pegg and Shahidi, 2012).
Dietary enrichment of broiler chicken meat with unsaturated fatty acids positively improved the intramuscular fat deposition. Baião and Lara (2005) reported that the broiler chicken fed with a diet containing sunflower oil (unsaturated fat) and bovine/swine fat (saturated fat) caused higher accumulation of intramuscular fat and abdominal fat. However, broilers fed with a diet containing 8% sunflower oil had significantly less amount of abdominal fat deposits than those fed with a diet containing 8% beef tallow (saturated fat). Thus, the location of fat deposition in broiler chicken depends on the kind of fatty acid added to the diet.

Dietary omega-3 PUFA on lipid oxidative stability of broiler chicken meat
Lipid oxidation in muscle and fat tissues affects the shelf-life of meat and meat products thereby deteriorate quality of meat products.
Membrane lipids (phospholipids) in the meat have a greater share of PUFAs, which are most prone to oxidation (Pegg and Shahidi, 2012). However, dietary enrichment of broiler chicken meat with PUFAs has become as a popular practice in the world due to human health concerns. Hence, the chance of lipid oxidation in broiler chicken meat is high. Studies revealed that the lipid oxidative stability is low in omega-3 PUFA enriched broiler chicken (Hugo et al., 2009b) especially, colour, flavorand shelf life of meat are affected (Smet et al., 2008;Betti et al., 2009). Although, dietary fish oil in broiler chicken ration causes "fishy taint" in broiler chicken meat through the oxidation of omega-3 PUFA which in turn reduce the feed intake of birds (Chashnidel et al., 2010) and consumer preference of chicken meat (Hugo et al., 2009a). countries, food and nutrion paper 53: animal production and health division and the food policy and nutrition division, Food and Agriculture Organization of United Nations (FAO), Rome.
More than 2% fish oil in the broiler chicken ration reduces consumer preference of chicken meat fed with that ration due to fishy smell in cooked meat (Mirghelenj et al., 2009). Moreover, oxidation of highly PUFA enriched meat may harm human health (Lypez-Ferrer et al., 2001).

Improving meat quality
Favourable enrichment of meats with omega-3 PUFAs depends on the dose of fish oil or other omega-3 rich PUFA sources (Leskanich and Noble, 1997;Bou et al., 2004). In this context, chicken diet should be enriched with less than 15-20 g fish oil per kg feed or less than 120 g fish meal per kg feed to minimise unpleasant aromas and flavours (Hargis and Van Elswyk, 1993;Leskanich and Noble, 1997;Howe et al. 2002). However, combining fish oils and vegetable oils and/or seeds could favourably increase the omega-3 PUFAs in chicken meat (Bouet al. 2005). Moreover, usage of quality fish oil and addition of antioxidants viz. vitamin E in the broiler chicken diets could improve oxidative stability of such meat.  Brinjal shoot and fruit borer, Leucinodesorbonalisis the most serious pest of brinjal. As currently the farmers rely exclusively on the application of pesticides to control L. orbonalis the level of contamination exceeded the Maximum Residue Limit (MRL) in brinjal fruits in India. By considering these impacts of insecticides the present study was conducted to formulate bio-intensive pest management (BIPM) against L. orbonalis.The survey conducted at Coimbatore and Erode districts confirmed the availability of pupal parasitoid of L. orbonalis, Trathalaflovo-orbitalis in the fields.The study on seasonal incidence of L. orbonalisat Thondamuthur, Coimbatore during the year 2014 revealed that the maximum (r= -0.78*) and minimum (r= -0.43) temperature negatively correlate with the damage intensity of L. orbonaliswhereas Relative Humidity (RH) (r=0.17) and rainfall (r=0.41) positively correlate with the damage intensity. Further it was found that the maximum temperature played a major role in adult emergence and fluctuating the population of moth.The biology of L. orbonalisrevealed that there was 5 larval instars in the lifecycle of L. orbonalisand the weather parameters existed in Rabi, 2013 (27 ± 5°C) promoted the fecundity, incubation period and hatchability of eggs of L. orbonalisas well as developmental period and growth of all life stages of L. orbonalis. Screening of 35 brinjal germplasms showed that the germplasm with lower shoot thickness, short fruit pedicel and calyx with higher trichome density on lower surface of leaves were less susceptible against the infestation of L. orbonalishence; priority should be given to these biophysical characteristics while developing host plant resistance varieties in breeding programmes. The pheromone trap efficiency studies revealed that Wota-T trap installed at crop canopy level with 3 mg lure concentration replaced at every 21 days were found effective in trapping the maximum number of L. orbonalismoths.Research on egg parasitoids of L. orbonalisis insufficient. Hence different Trichogrammaspecies of egg parasitoids were tested for their efficacy against L. orbonalisunder laboratory condition. Among the nine different species of Trichogramma, T. pretiosumand T. embryophagum performed well in laboratory and field conditions in reducing population of L. orbonalis with maximum yield in brinjal at field conditions. Further it was found that T. pretiosum(92%) and T. embryophagum(90%) had higher parasitization against the eggs of L. orbonaliswhereas T. chilonis, T. dendrolimiand T. evanescens had no efficacy against L. orbonalis. Moreover, it was noted that the parasitoids preferred freshly laid eggs of L. orbonalis for parasitization and the selection of eggs for parasitization was reduced with the aging of host eggs. In addition, parasitoids showed various emergence rates and maximum emergence rate was observed in T. embryophagum(90.2%) and T. pretiosum(87.5%). Almost all Trichogrammasp. tested in this study were eco-friendly and protected the other natural enemies prevailed in brinjal cultivation. Results of pathogenicity test of three entomopathogenic fungi @ 2 x 10 9 conidia per ml and Bt k®showed maximum mortality by Verticilliumlecaniiagainst all larval instars of L. orbonalis. Among the plant product insecticides and FORS, NSKE 5% had higher efficacy in functioning as ovicide, larvicide and adulticide against the L. orbonalis. Acetamiprid 20% SP performed well among newer molecular insecticides tested against the eggs of L. orbonalis. It was noticed that almost all insecticides reduced the shoot infestation substantially in 14 days after 2 nd spray. Chlorantraniliprole 18.5% SC was found to be the most effective insecticides in reducing shoot and fruit infestation in brinjal cultivation by L. orbonalis.Bio-Intensive Pest Management (BIPM) module with the management practices viz., installation of pheromone traps, seasonal release of Trichogrammapretiosum and T. embryophagum, spraying of Verticilliumlecanii, NSKE 5%, Acetamiprid 20% SP and Chlorantraniliprole 18.5%, evaluated against L. orbonalis on brinjal recorded a lesser shoot infestation of L. orbonalis as compared to farmer's practice. BIPM was found to be superior to farmer's practice in all aspects in the brinjal field experiment.

MPhil Thesis Abstrct
A study was conducted to determine the effects of climatic parameters and different crop management practices on induction of host plant resistance and population of beneficial insects towards management of viral diseases in chilli and tomato crops. Chilli (Capsicum annuum L.) variety MI Green and tomato (Solanum lycopersicum L.) variety Thilina were grown at five different locations of Sri Lanka, namely Kilinochchi, Mahailluppallama, Kundasale, Peradeniya and Rahangala under two crop management systems viz. pesticide-based management system and an IPM-based management system with less reliance on pesticides, during maha 2012/2013 and yala 2013 seasons. At each location, two crop management systems were tested in a nested treatment structure using a randomized complete block design with six replicates. Activity of defense enzymes, namely peroxidase, â-1,3-glucanase, chitinase, phenylalanine ammonia lyase and polyphenol oxidase was quantified spectrophotometrically in field grown chilli and tomato tissues collected at the first harvesting stage of the crops. Incidence of different types of virus diseases of tomato and leaf curl virus disease incidence of chilli were recorded over four crop growth stages, namely initial, crop development, mid season and late season. Abundance of different types of beneficial insects and herbivorous insects was quantified over the four different growth stages of two crops. Data on mean day temperature and daily rainfall were collected from each experimental site during the two cropping seasons. Relationships among virus disease incidence, defense enzymes activities of crops, population of beneficial insects and insect herbivores and climatic parameters were also analyzed. Findings of the study revealed that activity of all the defense enzymes in chilli and tomato tissues had a significant influence (p<0.05) by the cropping season, location, cropping season x location interaction effect, location x crop management practice interaction effect and cropping season x location x crop management system interaction effect. In general, there was no significant variation (p=0.05) between the two crop management systems on the activity of the enzymes in chilli and tomato tissues. It indicates the equal efficiency of both crop management systems on inducing the activity of enzymes in both types of crop tissues. There was no significant relationship (p=0.05) of virus disease incidence of the two crops with mean temperature of location or total rainfall of location. The beneficial insect population was significantly higher (p<0.05) in the two crops grown under IPM system than that under the pesticide management system. Moreover, the effect of management system on beneficial insect population was significantly influenced (p<0.05) by the location effect. A significant polynomial relationship (p<0.05) was observed between beneficial insect population and the mean temperature of location for both crops. No significant relationship (p=0.05) was found between the beneficial insect population and virus disease incidences of the two crops. Combined effect of virus disease incidence and herbivorous insect count had a significantly high influence (p<0.05) on the activity of defense enzymes in the two crop tissues. The IPM-based management system had lower environmental impact of pesticides compared to the pesticide-based management system used for both crops. Hence, it can be concluded that the IPM package tested in the study is as equally-capable as the pesticide-based management system in inducing defense-related enzymes in the plant tissues towards the management of virus diseases in chilli and tomato crops.

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