Effects of Chick Quality and Feed Oil Source (Soybean and Coconut) on Growth Performance and Carcass Parameters of BroilersABSTRACT
The present study aimed to determine whether replacing soybean oil with coconut oil in the feed affects the growth performance and carcass characteristics of broilers of different qualities. After hatching, chicks were separated by sex and divided into groups sorted by quality. A 2 × 2 factorial design was used, with chick quality (low and high) and feed oils (soybean and coconut) as the main effects, forming four treatment groups. A total of 800 chicks were used, with five replicates per group and 40 chicks per replicate. The initial live weights of these chicks were determined to be 44.01 g, 43.44 g, 44.73 g and 44.60 g for the low quality + soybean oil, low quality + coconut oil, high quality + soybean oil, and high quality + coconut oil treatment groups, respectively. This study showed that high-quality birds had significantly higher total feed consumption (p<0.05), but body weight gain and feed conversion rate were similar (p>0.05). Mortality was significantly higher in low-quality chicks, especially in the last three weeks (p<0.05). Low-quality female chicks had the highest abdominal fat amount and percentage (p<0.05). Birds fed coconut oil had a comparatively better feed conversion rate and higher body weight gain (p>0.05), and coconut oil had no significant effect on mortality or carcass quality (p>0.05). In conclusion, high-quality chicks outperformed low-quality ones, and coconut oil improved feed conversion without affecting mortality or carcass traits.
Keywords:
Broiler feeding; chick quality parameters; fatty acids; coconut oil
INTRODUCTION
As the world’s population steadily grows in recent years, it has become essential to increase the quantity and quality of food of animal origin in order to ensure adequate and balanced human diets. Although animal protein sources are of great importance for this, most people are undernourished in terms of consumption of these foods (Vandekerchove, 2014; Morgan et al., 2024; Sheffield et al., 2024; Andrews et al., 2025). Broiler farming has an important role in meeting the demand for animal protein sources, especially due to the short cycles and economic efficiency of broilers. Many factors (feeding, genetic factors, age of the flock, quality of hatching eggs, timing of egg collection, egg storage, hatching temperature, chick quality, etc.) influence the profitability, quantity and quality of poultry meat production (Durmuş & Kutlu, 2023; Kuda, 2023). These factors relate to the production process, from the feeding of the breeding flock to the slaughtering of broilers (Durmuş & Kutlu, 2019). Depending on the effects of all these factors, chicks of different quality are produced, and the success and efficiency of broiler production may vary depending on the quality of the chicks (Durmuş et al., 2021).
Chick quality can be defined as optimal chick development during the incubation period, together with a high growth rate, high breast meat percentage, and viability during the fattening period (Kamanlı & Durmuş, 2014). It should not be forgotten that nutrition in broiler rearing, just like chick quality, is a very important factor that significantly influences yield quantity and product quality.
Animals’ nutrient requirements - such as energy, protein, fat, vitamins and minerals - must be fully met to maintain their health and obtain products of the desired quality. As the digestive system of chicks is not yet fully developed after hatching, the feed consumed in the first week of production is mainly used for the development of the digestive system (Uni et al., 2000; Geyra et al., 2001; Maiorka et al., 2004; Uni & Ferket, 2004; Lamot et al., 2014; Ravindran & Abdollahi, 2021). A well-developed digestive system in the first week of production can have a positive effect on the chickens’ slaughter performance, as feed conversion increases in the subsequent period. It is therefore important to ensure that the digestion and intake of the feed given to the chicks in the first week of production is high. Medium-chain fatty acids and triglycerides have extensive antimicrobial activity that protects human and animal health (Skřivanová et al., 2006) and support and improve gut flora and health (Van Der Hoeven-Hangoor et al., 2013; Rial et al., 2016). Fatty acids have also reported to be growth factors, with a positive effect on animal health and yield performance, due to their organic acid structure (Khan & Iqbal, 2016).
This study investigated whether the replacement of soybean oil with coconut oil in the feed affects the growth performance and carcass parameters of broilers of different chick qualities.
MATERIALS AND METHODS
Ethical Statement
This study was approved by the Local Ethics Committee for Animal Experiments of Çukurova University (approval number: 2018/7).
Animal Material and Experimental Desing
Ross 308 Day-old chicks were obtained from a commercial hatchery where incubation followed the standard broiler hatching protocol described by McQuoid (2000). Fertilized eggs from a 62-week-old broiler flock were incubated after 24 hours of storage. At hatching, 1,200 chicks were randomly selected for quality assessment. Sexing was performed according to wing feather patterns, following Ross (2018) guidelines. Out of the 1200 chicks, 800 chicks (400 males and 400 females) were selected based on the quality criteria established by Durmuş & Kutlu (2023). The selected chicks were divided into two quality groups: ‘high quality’ and ‘low quality’. Each group was also divided into two feed treatments: one received a standard soybean oil-based feed, and the other was supplemented with coconut oil. This resulted in a 2x2 factorial experimental design (quality × diet) with five replicates per treatment group, each comprising 20 males and 20 females. The diets differed only in the type of fat source, either soybean oil or coconut oil. The coconut oil used is marketed under the name Grolux Synergy, contains about 60% medium-chain fatty acids, and was supplied by a private manufacturer. Coconut oil replaced soybean oil in the treatment diets. The fatty acid composition of the coconut oil used is shown in Table 1 (Boateng et al., 2016).
In view of the age-dependent changes in the nutritional requirements of the chicks, three different types of feed starter, grower and finisher feed were offered, each differing in pellet size, nutrient composition (analyzed values, %), and ingredient composition (Table 2). These corn and soy-based compound feeds were produced by a commercial feed manufacturer in pellet form (3-4 mm diameter). All feeds were specially formulated and manufactured by a private feed mill in Adana, Türkiye, to meet the nutritional requirements for each stage of chick development.
The birds were reared in an environmentally controlled house with a total of 20 pens (3 × 1 m) and 24-hour daily lighting. Feed and water were provided ad libitum throughout the experiment. The animal density in each pen was set at 17 chicks/m2, similar to commercial conditions. During the experiment, the ambient temperature and humidity were kept within the animals’ comfort zone using a curtain and a tunnel ventilation system, as recommended by Ross (2018).
Measurements and Analytical Methods
The quality of the chicks was evaluated based on the criteria defined by Durmuş & Kutlu (2023), whereby an overall quality score was calculated by adding the individual parameter values. Accordingly, chicks with a total score of 80-100 were classified as high quality, chicks with a total score of 60-79 were considered low quality, and chicks with a total score below 60 were classified as off-track chicks (Table 3). The weighted scores (30% for legs, 30% for eyes, 20% for feather color, and 20% for chick length) of these criteria were determined by evaluating leg structure, eye condition, feather color, and chick length. These weightings were determined by the perceived importance of each trait in defining a healthy chick. Rather than assessing the isolated or interactive effects of each trait, the assessment focused on their cumulative contribution to the overall quality of the chicks.
The leg structure and eye condition of the chicks were assessed by visual inspection. Feather pigmentation in the neck region was assessed using the DSM-S yolk color scala, while chick length was determined by measuring the distance from the tip of the beak to the tip of the middle toe with a ruler. The reference range for measuring chick length was determined in a preliminary test with 200 eggs from a 62-week-old breeding flock.
Calculation and Statistical Analysis
Weekly feed intake was monitored for each subgroup, while body weight was measured weekly separately for males and females using a digital scale. Feed conversion rate was determined by dividing the total food intake by the corresponding body weight gain in each subgroup, following the equation below:
Mortality data were recorded daily by sex and treatment group. At 35 days of age, all birds were slaughtered for collection of carcass data. Five males and five females representing the average live weight of each replicate were selected for carcass evaluation. Immediately after slaughter, the carcasses were weighed to determine the hot carcass weight. They were then chilled at +4 °C for 24 hours, after which the weight of the cold carcasses was determined. The carcass yield and abdominal fat were calculated using the following formulas, according to the method described by Durmuş & Kutlu (2023):
Data were statistically analyzed using the SAS software (version 9.4; SAS Institute Inc., Cary, NC, USA) in a 2×2 factorial design. Differences between treatment means were assessed using Duncan’s Multiple Range Test implemented in SAS. Mortality data were analyzed using chi-square (X²) procedures. All results were expressed as mean values per bird together with the standard error of difference (SED) between the means. A significance threshold of 0.05 was used for all statistical tests.
RESULTS
After quality grading at the beginning of the experiment, a significant difference was found between the initial body weight of the low-quality and high-quality chick groups (p<0.05; Table 4). Although body weight was not considered in the quality classification, the initial body weight of the high-quality groups was higher than that of the low-quality groups. The effect of chick quality and the use of coconut oil in the diet on body weight gain was found to be significant on day 21 of the trial. The groups fed diets with coconut oil achieved higher body weight gain on day 21 of the trial (p<0.05); however, this effect disappeared in the other weeks (p>0.05). According to the data obtained on day 35 of the trial, chick quality had a significant influence on feed consumption (p<0.05; Table 4), as high-quality chicks consumed more feed than their low-quality counterparts. It was also observed that the use of coconut oil in the diet led to no significant effects on feed consumption (p>0.05).
The use of coconut oil instead of soybean oil in broiler diets had a significant effect on feed conversion at days 14 and 21. According to this result, the groups fed diets with coconut oil had better feed conversion. It was also found that the difference in quality between the chicks had a significant effect on feed conversion on day 28 of the trial (p<0.05). Mortality is one of the most important factors affecting the profitability and success of broiler production. Although the mortality rate was lower in high quality chicks on day 21, 28 and 35 (p<0.05; Table 5), the use of coconut oil instead of soybean oil in broiler diets had no significant effect on mortality (p>0.05).
When looking at the slaughter and carcass characteristics at the end of the trial, there was a significant influence of chick quality on the hot (p<0.05) and cold carcass weights (p<0.01) of the males (Table 6).
In addition, a significant influence of chick quality on abdominal fat weight and ratio was found in females (p<0.05). However, different fat sources used in feeds did not affect slaughter and carcass characteristics of males and females (p>0.05).
DISCUSSION
Many factors (e.g., incubation conditions, age of the breed, feeding of the breed) influenced the live weights of chicks at the beginning of the experiment, impacting it after hatching. The relationship between the live weight of the chicks after hatching and slaughter weight is still unclear. Powell & Bowman (1964), Molenaar et al (2008), Narinç & Aydemir (2021), and Durmuş & Kutlu (2023) reported a positive relationship between these two parameters, which is consistent with the results of the present study. However, Decuypere (1979), McLoughlin & Gous (1999), Wolanski et al. (2003), and Tona et al. (2004) found no relationship between initial and slaughter weight in broilers. In contrast to the present study, Vieira and Moran (1999) found a negative relationship between the parameters of interest. McLoughlin and Gous (1999) observed no relationship between daily chick weight and slaughter performance, but chick weight at 7-10 days of age was closely related to slaughter weight. There are still relatively few studies on the relationship between slaughter performance and chick quality that account for qualitative parameters.
In a study conducted with broilers divided into quality groups at the beginning of the trial, high-quality chicks had an average of 1.32 g higher live weight and an average of 37.59 g higher body weight gain than the low-quality chicks at the end of the trial, regardless of sex (Durmuş & Kutlu, 2023). In the same study, chick quality did not have a dramatic effect on body weight gain and feed consumption. However, feed conversion rate on day 28 of the trial was significantly better in high-quality chicks than in low-quality ones. It was also found that the mortality rate on days 7, 14, 21, and 28 of the trial was significantly lower in high-quality than in low-quality chicks. Although chick quality did not have a dramatic effect on carcass parameters, the same study found that both the abdominal fat weight and relative abdominal fat weight of females were significantly higher in low-quality than in high-quality chicks. The results of the current study are consistent with the findings of Durmuş & Kutlu (2023).
When 1.5% of soybean oil during the starter phase (0 to 21 days) of broiler feeding and 3.0% of soybean oil during the grower phase (22 to 42 days) were replaced with coconut oil, which is rich in MCFAs (0, 25, 50, 75 and 100%), the researchers found no significant effects on feed consumption, body weight gain and feed conversion ratio of the chickens (Wang et al., 2015). Shokrollahi et al. (2014) reported similar results after adding 0.1, 0.2 and 0.3 % MCFAs to broiler rations. In another study, Chiang et al. (1990) added MCFAs at a concentration of 30, 60 and 90% instead of 7% soybean oil to broiler rations and there was no dramatic effect on body weight gain. In another study by Khosravinia (2015), the addition of 0 g/kg, 1.5 g/kg and 2 g/kg of MCFA (Vitamex, Drongen, Belgium) to broiler rations had no significant effect on feed intake and FCR; however, it was reported that body weight gain increased and mortality decreased the higher the dose of MFCAs added to the ration. Gantois et al. (2013) reported that a commercial MCFA supplement (Aromabiotic® Poultry - 60% OZYA content) to broiler diets had no effect on cumulative feed consumption, but found that daily body weight gain and feed conversion ratio increased significantly and mortality rate decreased. In a similar study, Khatibijo et al. (2017) reported that MFCAs added to feed had no significant effects on body weight gain and feed intake; however, it was found that the effects on FCR were significant during the first 12 days of production. The results of the current study are largely consistent with reports by Wang et al. (2015), Shokrollahi et al. (2014), Chiang et al. (1990), Khosravinia (2015), Gantois et al. (2013), and Khatibijo et al. (2017), reporting that the use of MCFAs in broiler rations does not noticeably affect feed intake. The use of MCFAs in the ration in the present study improved feed conversion on day 14 and 21, similar to the findings of Khatibijo et al. (2017) and Gantois et al. (2013). In addition, the addition of MCFAs to the ration increased body weight gain on day 21, similar to the findings of Khosravinia (2015) and Gantois et al. Although mortality rate was significantly lower in high quality chicks at day 21, 28 and 35, the use of coconut oil instead of soybean oil in broiler diets had no significant effect on mortality, contrary to the findings of Khosravinia (2015) and Gantois et al. (2013). This result can be explained by the fact that high quality chicks are better in terms of time of access to feed and water and their adaptation to the environment in the first days of production. Khosravinia (2015) and Khatibijo et al. (2017), in agreement with the results of the current study, found that the use of MCFAs in broiler diets had no effect on hot and cold carcass weight, carcass yield, abdominal fat weight, and relative abdominal fat weight. However, studies by Wang et al. (2015) and Shokrollahi et al. (2014) reported that the use of MFCA in the diet reduced abdominal fat weight and relative abdominal fat weight.
Furthermore, Chiang et al. (1990) found that the addition of medium-chain triglycerides replacing soybean oil in the rations reduced body fat percentage and increased body protein percentage in parallel with the increase in the amount of triglycerides in the ration. Mabayo et al. (1993) observed a significantly increased body protein accumulation as well as a significantly reduced amount of fat stored in the body and a lower fat storage level after adding medium-chain triglycerides replacing long-chain triglycerides in broiler rations. In contrast, Furuse et al. (1992) reported that the addition of medium-chain triglycerides drastically reduced protein accumulation and body fat storage compared to groups in which long-chain triglycerides were added to broiler rations. In the study conducted by Wang et al. (2015), it was found that adding coconut oil in replacement of soybean oil in chicken rations decreased the amount of fat stored in the body in parallel with the increase in coconut oil. The same researchers further reported that replacing soybean oil with coconut oil at 75% in the ration was the best way to reduce the amount of fat stored in the body without affecting the chickens’ yield performance. In contrast to the literature, the findings of the present study showed that the weight of abdominal fat and the relative weight of abdominal fat increased with the use of coconut oil in the ration, especially in female chicks.
CONCLUSION
In the present study, the effects of chick quality and the addition of coconut oil replacing soybean oil in the feed on the performance of broilers were investigated. At the beginning of the trial, the qualitative classification, which did not take into account the live weight of the chicks, showed that high-quality chicks weighed 0.94 g more than low-quality chicks. This superiority was reiterated at the end of the experiment, with 8.26 g more among the high-quality chicks. These results indicate that body weight after incubation could be a reliable quality parameter to distinguish between high- and low-quality broilers. It was also found that mortality was lower in high-quality chicks than in low-quality ones. According to these results, undesirable situations such as chick mortality, growth retardation and low slaughter weight can be minimized if production starts with high-quality chicks. This increases the income from production and enables economic production. It was also found that the use of coconut oil in the diets generally reduced feed consumption, improved feed conversion, and had no significant effect on mortality and carcass parameters.
ACKNOWLEDGEMENTS
None.
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FUNDING
None.
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DATA AVAILABILITY STATEMENT
Data will be available upon request.
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