Evolving Emulsifier Supplementation Strategy for Low Energy Diet in Broiler Chickens

In developing countries broiler industry is growing dramatically to meet out the protein requirement of humans. Feed efficiency and growth rate of broilers have improved drastically in the last few decades. Current high-performance commercial hybrid broilers require high energy diet which is important to exploit their full genetic potential. Feeding with maize, barley and other energy sources alone is not sufficient to meet out their energy requirement. Therefore, use of high energy sources like oil and fat play a major role in their feed formulation. Fats also provide varying quantities of the essential nutrient linoleic acid (Leeson and Summers, 2001). Another important role of fats in diet is its inhibition from de novo lipogenesis in broiler chickens (Yeh and Leveille, 1971) which increase energy efficiency in diets. Tallow is saturated animal fat and has 42.5% saturated fatty acid and 1% unsaturated fatty acid (Manilla et al., 1999).  Young chicks have limited digestibility of tallow hence, it is used only in later stage of feeding (Leeson and Summers, 2001). The use of vegetable oils and animal fats in broiler diets has been beneficial for poultry production. They often present higher than expected biological value, increasing dietary metabolizable energy, which usually results in higher growth rates and better feed efficiency due to low heat increment. Studies in poultry nutrition has shown that fat digestion in young chick  is low due to poor emulsification by bile salts than lipases deficiency and this has led to interest in the use of emulsifiers to improve the utilisation of fats in young birds (Krogdahl, 1985). Hence, this study was planned to evolve emulsifier supplementation strategy in low energy diet containing tallow as fat source in broiler chickens. 

The present experiment was conducted during the month of March to April, 2018 at Veterinary College and Research Institute Tirunelveli constituent college of Tamil Nadu Veterinary and Animal Sciences University (TANUVAS), Tamil Nadu, India. A total of 150 day old Vencobb-320 broiler chicks belonging to single hatch were purchased from local hatchery, wing banded, weighed and randomly distributed into three treatments with 5 replicates of ten chicks each using completely randomized design. Feed and water were provided ad lib for all the chicks. All the chicks were reared under standard managerial conditions throughout the experimental period in deep litter system. Iso nitrogenous experimental diets were prepared (Table 1) as per Bureau of Indian Standards (BIS, 2007). The emulsifier used in this experiment was purchased from Jubliant Life Sciences, Noida. Crude soybean oil and tallow were used as fat source in starter and finisher diet and only crude soybean oil was used in pre starter diet. Three treatments were planned as chicks were offered with basal diet (T₁), basal diet supplemented with emulsifier at the rate of 250 g per MT of feed (T₂) and in pre starter- 2.7%, starter- 2.6% and finisher- 2.5% energy was reduced from basal diet supplemented with emulsifier at the rate of 250 g per MT of feed (T₃). Body weight of chicks and feed consumption were recorded weekly and feed conversion ratio was calculated. Blood samples were collected at the end of the experiment from wing vein to study the serum biochemical parameters using semi auto analyser. At the end of experiment, three birds from each replicate were selected randomly and slaughtered ethically to study the carcass parameters. Data were analysed using completely randomized design with one way analysis of variance as per the procedures of Snedecor and Cochran (1989) using statistical analysis software (IBM SPSS version 20.0 for windows).
 

Growth performance
 
The mean cumulative body weight is given in Table 2. There was significant difference (p<0.05) in cumulative body weight between treatment groups in all weeks of age except in second and fourth week of age. The emulsifier supplementation significantly increased body weight in all the weeks of trial period. Emulsifier added group (T₃) showed significantly higher body weight than T₁ and T₂ groups in all the weeks. The cumulative body weight of T₂ group and T₃ group are comparable except in 6^th week. At 6^th week of age highest cumulative body weight was recorded in T₂ group (2689 g) followed by T₃ group (2546 g) and T₁ group (2513 g).  Results of this experiment agreed with Uredime et al., (2018) who revealed that the average final weight at finisher stage was significantly highest for tallow with emulsifier supplemented group (2734 g) followed by tallow with enzyme supplemented group. The performance of birds in tallow with emulsifier supplemented group were attributed to the addition of  an emulsifier, which increased digestion of fat containing long chain, saturated fatty acids (Poline, 1980).
        

 
Melegy et al., (2010) reported that the use of an emulsifier based on lysolecithinate @ 0.25 or 0.5 kg/ton of feed significantly improved productive parameters. Findings of Bontempo et al., (2018) showed a significant improvement in average daily gain with the supplementation of synthetic emulsifier to the feed for one to 12 days. In contrast to this results, Zampiga et al., (2016) reported that addition of the emulsifier did not statistically improve final body weight compared to control. Zhang et al., (2011) who also found that body weight gain was lower (p<0.05) in broilers fed diets containing tallow than in those chicks fed diets containing soybean oil or poultry fat  during the starter and the grower periods. Ferreira et al., (2005) did not find any significant difference in production performance among birds fed soybean oil and tallow with emulsifier. The findings of this study is in agreement with an earlier report stating that supplementing emulsifier in broiler diet is more important during the early age because lipase activity in chickens reaches at its peak usually during 40-56 days of age (Krogdahl and Sell, 1989).
        
The data on cumulative feed intake revealed significant difference in feed intake among treatment groups in all the weeks of age except during 2^nd week (Table 3). At 6^th week significantly lowest feed intake was recorded in T₃ (4312 g) group followed by T₁ (4505 g) and T₂ (4603 g) groups. The feed intake of broilers may vary depending on the size of the feed, which requires a more precise study of growth performance. The feed conversion ratio was comparable between T₃ (1.72) group and T₂ group (1.74) but significantly different from T₁ (1.82) group at 6^th week of age (Table 4). In this study reduced energy in the diet influence the feed intake and body weight gain but addition of emulsifier improved the fat digestion which results in improved feed conversion ratio. Bontempo et al., (2018) reported that FCR was lower when fed AMT emulsifier from 22^nd day to 44^th day. The result of this experiment also agreed with Roy et al., (2010) who reported beneficial effects on digestibility and feed efficiency in broiler chicks with exogenous emulsifiers. The improved feed conversion ratio may be due to effect of fat emulsifier which improves fat digestibility and energy utilization. In contrast to the results Uredime et al., (2018) revealed that emulsifier supplementation did not affect the feed conversion ratio at both phases and among the treatments significantly.
 

 

 
Serum biochemical parameters
 
The data on serum biochemical parameter revealed no significant difference (p>0.05) in all the biochemical parameters among the treatment groups (Table 5). Serum concentration of glucose is high in T₃ (661.14 mg/dl) and T₂ (642.2 mg/dl) than T₁ group (628.28 mg/dl) indicated that T₃ group has 5.2% and T2 group has 2.2% more of serum glucose compare to T₁ group. This available glucose due to emulsification was utilized for higher growth in emulsifier supplemented groups. The results of this study agreed with Guerreiro Neto et al., (2011) that total cholesterol, HDL or triglycerides were not affected by dietary fat source and emulsifier addition.  Wang et al., (2016) also did not observe emulsifier supplementation had any effect on serum total triglycerides, cholesterol, HDL and LDL concentrations of broilers fed on low energy diet. Similarly, Wang et al., (2017) reported that even in sows addition of emulsifier with diet had no difference in cholesterol, triglyceride, HDL and LDL cholesterol. This response in serum biochemical parameters may be related to the type of fat source whether vegetable oil or animal source and their inclusion level. In broilers multiple potential mechanisms were involved in the regulation of serum cholesterol level and other parameters (Bontempo et al., 2018).
 

 
Carcass parameter
 
The effects of supplementing emulsifier on carcass parameters were given in Table 6. The data revealed that there is no significant difference (p>0.05) noticed in dressing percentage, breast meat yield and drumstick percentage and abdominal fat percentage among treatment groups. Numerically higher dressing percentage was noticed in T₂ (68.26%) and T₃ group (66.73%) followed by T₁ group (65.67%). Similarly, Zampiga et al., (2016) reported that no differences were observed among the experimental groups supplemented with lyso-phospholipids emulsifier regarding the eviscerated yield as well as for the percentage of breast, legs and unseparated wings. Similarly, Melegy et al., (2010), Guerreiro Neto et al., (2011) and Aguilar et al., (2013) stated that the dietary use of emulsifiers did not affect carcass yield of broilers.
 

Results from the current study concluded that emulsifier supplementation with reduced metabolic energy can be used as a feeding strategy in broiler diet in order to improve production performance.