Effect of Dietary Supplementation of Safflower (Carthamus tinctorius L.) Seed on the Growth Performance, Blood Lipid and Meat Quality of Broiler Chickens

Chicken meat is preferred over other meats because it contains more protein and less cholesterol (Kralik et al., 2018). Poultry meat, particularly broiler meat, is widely accepted in almost all the countries despite cultural taboos about meat consumption (Sudharsan et al., 2021). The poultry and related industries are facing problems because of high prices of feed ingredients such as maize, soybean, chickpea and other cereals, especially in developing countries. Presently, people are more health-conscious and want functional food to improve their long-term health goals (Bharath et al., 2017). Therefore, there is a need to look for alternative cheaper, easily available, nontoxic oilseed with some functional properties. In this context, safflower seed might be an important alternative source of fats and oils enriched with functional PUFA and MUFA.

Oil of Safflower is rich in polyunsaturated fatty acid (PUFA) linoleic acid (77%) (Singh and Nimbkar 2016). The number of studies demonstrating the positive effects of PUFA, including fats of animal origin, on human health has recently increased (Djuricic and Calder 2021). PUFA decreases blood cholesterol which is one of the contributory factor for coronary heart disease. Specifically, conjugated linoleic acid has inhibitory effects on cardiovascular diseases, diabetes, cancer, obesity and many more (Karabacak et al., 2015). However, nutritional importance of safflower seeds has not been extensively tested in poultry. Therefore, the current investigation was performed to study the effect of safflower seeds supplementation on lipid profile, growth performance and meat color of broiler chicken.

The feeding trial was conducted in the poultry farm of the Department of Dairy Science and Food Technology, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi, India. Two hundred one day old broiler male chicks (cobb-400) were procured from a commercial company. The chicks were kept in deep litter system and fed with basal diet for one week just before starting the trial. After one week, weight of the chicks were taken and they were divided into five separate groups. Each group comprised of 40 broilers each, with five replicates of eight broilers per replicate. Required amount of feed with drinkable water was provided ad libitum. The brooder’s temperature was maintained at 33±1°C from day one of the trial to 14th day and then gradually decreased to 26±1°C by 28 days old, after that the chicks were kept at room temperature. Through out the 35-days of the experiment, all the birds were kept under the same management settings until they reached the age of 42 days. The chicks were vaccinated in accordance to the vaccination protocol.

Table 1 shows five iso-caloric and iso-nitrogenous diets that were formulated to meet the broilers’ nutritional needs as per Nrc (1994). Besides the basal control diet, four experimental diets were formulated to contain safflower seed (2.5%, 5%, 7.5% and 10%). The diets were formulated for two-phases, first starter phase (7-21 d) and finisher phase (22-42 d). The experimental diets fed to the birds were evaluated for proximate principles as per Aoac (2000).



The gain in body weight of birds and weight of feed provided to them were recorded each week up to 42 days. Under each dietary regimen, the cumulative weekly and overall body weight gains (BWG), feed intake (FI) and feed conversion ratio (FCR) were determined. Furthermore, during the trial, growth efficiency parameters such as energy efficiency ratio (EER) and protein efficiency ratio (PER) were determined as per Rokade et al., (2017).
 

PER = Weight gain ÷ Protein intake
 
EER = ME intake (kcal) ÷ Weight gain (g)

 
At the end of the experiment, two birds were chosen at random from each replication and 5 mL of blood sample was drawn out from the wing veins and placed in non-heparinized tubes without anticoagulants. The serum from the blood was separated by centrifugation process at 2000 rpm for 10 minutes and the samples were kept at -20°C for biochemical analysis. Commercial diagnostic kits (Qualigens India Pvt. Ltd.) were used to measure triglyceride (TRI) levels, high-density lipoprotein-cholesterol (HDL-C) and total cholesterol (CHO) according to the manufacturer’s recommendations. Friedewald’s formula was used to analyze both low-density lipoprotein cholesterol (LDL-C) and very low-density lipoprotein cholesterol (VLDL-C) (Aba et al., 2019). 
 

LDL-C = CHO - (HDL-C + TRI ÷ 5)
 
VLDL-C = 1 ÷ 5 of TRI

 
The color of broiler meat (L*, a*, b*) were measured by Color Flex, Hunter Lab. Raw meat samples were taken out from the left thigh and breast and were kept in Petri plate and then placed to the sensors of the colorimeter to analyze their color. Three color coordinate values were expressed as the mean values of lightness (L*), redness (a*) and yellowness (b*). After 24 hours of slaughter, meat sample (10 g) from the left side of thigh and breast was taken and homogenized with 100 ml of distilled water to measure the pH value. Buffer solution of pH 4 and pH 7 was prepared for calibration. The pH values were recorded by dipping the glass electrode of digital pH meter (Systrong µ pH system) into the homogenized solution. The water-holding capacity (WHC) was also measured as per the procedure described by Wilhelm et al., (2010).

The study involved a completely randomized design (CRD) with five treatments and five replications in each treatment. Data of this study were examined using one way ANOVA and Duncan’s multiple post-hoc range tests, which is a common statistical approach Snedecor and Cochran (1989). Statistical treatments were performed by using SPSS version 25. Significance levels were declared at (P<0.05).

Growth performance
 
Weekly body weights (BW) of broiler chickens are shown in Fig 1. The results indicate that there was no significant difference in body weight between the trial groups during first two to three weeks. While, a progressive increase in BW was observed with an increased level of safflower seed from the fourth to sixth week of the trial. At the end of the feeding trial i.e. during sixth week, the highest BW was recorded in 5% safflower seed group and the lowest was observed in the control group with 0% safflower seed. The body weight with 5% safflower seed was found significantly higheras compared to all other tested levels. Compared to 2.5% and 5% safflower seed groups, the BW gain in the last three weeks was modest to low in the 7.5% and 10% safflower seed groups. The reason behind this may be due to the higher fiber content in the 7.5% and 10% safflower seed groups, which lead to decrease in the diet intake. A similar pattern was observed in the BW of the birds up to five weeks of age which were fed with 5 g and 10 g of safflower oil (Amer et al., 2021). Malakian and Hassanabadi (2010) reported higher BW of broiler chicken fed with 5% safflower seed during 21-42 days. In another study, the chickens body weight did not get significantly affected when they were fed with 0%, 10% and 20% safflower but numerically the BW were higher in the group that were fed with 10% safflower (Oguz and Oguz 2007).



The performance data for the starter and finisher phases (Table 2) revealed that there was no (P>0.05) difference in FI and FCR between all groups during the trial period of 7-21 days of birds age. However, there was a significant difference in FCR when correlated between the treated groups and the control group during the finisher phase (22-42 days of age). FCR of birds which were fed with supplemented diet of 5% safflower seed was found better as compared to other groups. EER was significantly higher in 0% safflower seed group and lowest in 5% safflower seed group during starter and finisher phase. PER was significantly higher in 5% safflower seed group, while the lowest PER was observed in 0% safflower seed group. Moreover, there was no (P>0.05) difference between groups of 7.5% and 10% safflower seed. This could be because the 5% safflower seed group has more lysine than the other groups, while the 0% safflower seed group had the least. Lysine is an essential amino acid that improves the conversion of protein into metabolic activities, energy and tissue production. This is possible because higher amino acid present in the diet or body synthesize the muscle in much better way (Nasr et al., 2011). Increased level of safflower seed in the diet gave poor results of PER, EER and FCR indicating poor efficiency of feed with respect to protein and also poor energy utilization by the birds.



These results agree with Jalali et al., (2015) who reported that supplementation of soybean oil containing high PUFA to the broilers diet significantly increased (P<0.05) the FCR and increase in body weight was also observedin broilers during entire rearing phase and growing period. Manohar and Edwin (2015) also found that omega-3 PUFA supplementation to the quail diet significantly affects weight gain without significant difference in feed efficiency and intake. Abdulla et al., (2017) compared soybean oil and linseed oil and found that soybean oil supplementation increased (P<0.05) BW at sixth weeks while no such significant increase was found in linseed oil supplemented diet. However these findings are in contrast with Ebeid et al., (2011), who had reported that growth performance like BW, FI, or FCR is not adversely affected by diet supplemented with omega-3 PUFAs in Japanese quail. PUFA in the diets enhances growth performance of broiler birds. Oils like rapeseed oil, sunflower oil and canola oil are rich in unsaturated fatty acids which have better intestinal absorption due to hydrolysis of monoglyceride and micelle formation compared to saturated fatty acids Sudharsan et al., (2021).
 
Serum lipid profile
 
Increasing levels of safflower seed supplementation in the diet (P<0.05) affected serum lipid profile except for HDL (Table 3). The level of total cholesterol (CHO) concentration tended to be lower (P<0.05) when fed with higher levels of safflower seeds. Saleh and Alzawqari (2021) observed that the serum concentration of CHO level decreased in birds fed with different levels of olive cake meal. A similar type of result was found in the study of Saleh et al., (2020) and Cayan and Erener (2015) in which the level of cholesterol decreased significantly in birds fed  with different levels of olive cake meal and olive leaf powder. It was also observed by Rama Rao et al., (2004) that serum concentration of CHO levels decreased in birds fed with different levels of sunflower meal. Safaa et al., (2014) reported that on addition of oat hulls in broiler diets caused a linear reduction lipid profile, like total cholesterol and triglycerides in 3 weeks of broilers. This might be due to high fiber contained in the diet. The decrease in the levels of serum lipid metabolite which are found to be by the dietary supplements of insoluble fiber is because of bile lipid binding ability of fibers in the animal gut Sarikhan et al., (2009). These findings are in contrast with Oguz and Oguz (2007) and Selvaraj et al., (2004) whose observation showed that there was no significant difference in CHO levels when birds fed different levels of full-fat safflower and full-fat sunflower seeds. During the present study, there were no significant differences between 7.5% and 10% safflower seed groups in TRI, LDL-C and VLDL-C. Malakian and Hassanabadi (2010) also observed that the concentration of plasma TRI was lower in the birds which were fed with higher amount of full-fat safflower seed during 21-42 days and this effect was found not significantly different (P>0.05). The lower TRI values found in chickens fed with the highest levels of safflower seeds may be due to the specific fatty acids that stimulate oxidative beta pathway enzymes. Furthermore, in birds, using an oil seed crop increases the activities of S-3-hydroxy acyl-CoA dehydrogenase and carnitine palmitoyltransferase-1. As a result, enhanced carnitine palmitoyltransferase-1 activity would increase the availability of fatty acids for oxidation (Sanz et al., 2000). By feeding various levels of safflower seed, HDL-C did not significantly differ between control and treatment groups, but LDL-C and VLDL-C were significantly decreased. The result are suggertive of the fact that diets containing high linoleia cid poditively effect on plasma CHO TRI, LDL-C and VLDL-C cholesterol in broiler birds but has a negative effect on HDL-C in birds.
 
​

Meat quality
 
The different level of safflower seed supplemented diet showed significant effect on meat quality in broiler chickens (Table 4). This study elucidated that increasing levels of safflower seed in the supplemented diet does not pose significant effect (P>0.05) on pH, meat color and water holding capacity during the entire experimental period. The color of meat is an important parameter deciding the quality of meat and is one of the most influential parameter determining customer acceptability of meat and meat products (Adeyemi et al., 2014). The intense dark or light colors have been reported to be indicators of the poor meat quality (Benli et al., 2016). Myoglobin and pH affect meat color and meat pH is favorably connected to redness, but negatively to yellowness and lightness (Han et al., 2012). Decrease in water-holding capacity lead to a drop in surface light reflectance also. The WHC is the most important parameter of meat which decide its quality particularly its texture, palatability and cooking characteristics.

​

The supplementation of the diets with different levels of safflower seed (2.5, 5.0, 7.5 and 10.0%) resulted into increased growth performance of the broiler birds. The best result in terms of enhanced growth performance, improved serum lipid profile and meat quality was obtained with supplementation of 5% safflower seed. The PUFAs and MUFAs of safflower add to the functional health benefits from the meat obtained from the broiler birds fed on diets supplemented with this oilseed.

The authors would like to thank the Department of Dairy Science and Food Technology, Banaras Hindu University, Varanasi, India for their facilities and support in carrying out this research.