Effect of Fat Sources and Emulsifier Levels in Broiler Diets on Performance, Nutrient Digestibility, and Carcass Parameters

08/March/2019 Approved: 22/October/2019 ABSTRACT The objective of the current study was to check the effect of fat types and polyglycerol polyricinoleate (PGPR) levels in broiler diets on broilers performance. For this purpose, three sources of fat {soy oil (SO), poultry oil (PO), and oxidized oil (OO) (oxidized soy oil)} and four levels of PGPR were used in a 3×4 factorial arrangement. The trial had 12 different dietary treatments: (T1) basal ration (BR) containing SO without PGPR supplementation, (T2) BR containing PO without PGPR supplementation, (T3) BR containing OO without PGPR supplementation, (T4) BR containing SO with PGPR supplementation (0.025%), (T5) BR containing PO with PGPR supplementation (0.025%), (T6) BR containing OO with PGPR supplementation (0.025%), (T7) BR containing SO with PGPR supplementation (0.035%), (T8) BR containing PO with PGPR supplementation (0.035%), (T9) BR containing OO with PGPR supplementation (0.035%), (T10) BR containing SO with PGPR supplementation (0.045%), (T11) BR containing PO with PGPR supplementation (0.045%), (T12) BR containing OO with PGPR supplementation (0.045%). Results revealed that interaction was present for fat sources and PGPR levels in the current experiment ( p<0.05 ) for feed conversion ratio, body weight, dry matter (DM) and crude fat (CF) digestiblities ( p<0.05 ). In overall trial, interaction results of PGPR and fat sources showed that performance of birds and nutrient digestiblities of DM and CF was increased in birds received diet contained SO and PGPR @ 0.35%. It is concluded that PGPR @ 0.035% could be successfully used in broiler ration contained soy oil to


INTRODUCTION
In commercial broiler diets, vegetable oils and animal fats are being used to improve the growth rate and feed efficiency (Blanch et al., 1996;Tavárez et al., 2011;. However, the lower potential to synthesis and secrete bile salts in young broilers results in lower digestibility of fats and poor performance of growing broiler (Noy & Sklan 1998;Upadhaya et al., 2017). Several researchers reported that addition of external emulsifiers in the diet of broilers improves fat digestibility and growth rate of broiler (Emmert et al., 1996;Huang et al., 2007;Zaefarian et al., 2015;Zhao et al., 2015). Different types of emulsifiers are being used in the diet of poultry to enhance fat digestibility, growth rate, feed efficiency and meat quality (Emmert et al., 1996;Huang et al., 2007;Zaefarian et al., 2015;Zhao et al., 2015). Examples of commercially available emulsifier for poultry are sodium stearoyl-2-lactylate (SSL), 1, 3-Diacyl glycerol, lyso phospholipids, lyso phosphatidylcholine, Tween 80, Tween 20, and soy lecithin Upadhaya et al., 2016; eRBCA-2019eRBCA- -1158eRBCA- et al., 2017Zaefarian et al., 2015;Zhao et al., 2015). The selection of external emulsifier is critical and depends upon the fat sources used in the broiler diet. Generally, emulsifier hydrophiliclipophilic balance (HLB) is considered a good criterion to select a suitable external emulsifier for poultry diet (Hasenhuettl & Hartel 2008). For example, in the study of Upadhaya et al. (2017) 'sodium stearoyl-2-lactylate' HLB value of 20 have been used in broiler ration. Similarly, Upadhaya et al. (2017) also used 'Tween 20' with an HLB value of 12 in the ration of broilers.

Effect of Fat Sources and Emulsifier Levels in Broiler Diets on Performance, Nutrient Digestibility, and Carcass Parameters
Polyglycerol polyricinoleate (PGPR) is a commercially available emulsifier made from glycerol and fatty acids with an HLB value of 16. Polyglycerol polyricinoleate is well known emulsifier for food industry (Bastida-Rodríguez, 2013). However, there is no available study, that evaluated the effects of PGPR on intake, growth, nutrient digestibility and meat quality of broilers. Therefore, the purpose of the current research was to introduce a new emulsifier in the broiler industry. However, some researchers reported that the inclusion of emulsifier in broilers diets had no effects on performance of broiler Upadhaya et al., 2016;Upadhaya et al., 2017;Zhao et al., 2015). Furthermore, researchers also reported that inclusion of external emulsifier in the diet of broiler performed differently on different fat sources Upadhaya et al., 2016;Upadhaya et al., 2017;Zhao et al., 2015). Therefore, current experiment was planned to evaluate the effects of three fat sources (Soy oil, poultry oil, and oxidized oil (soy oil)) with different levels of PGPR supplementation on feed intake (FI), body weight (BW), feed conversion ratio (FCR), nutrient digestibility, meat quality, and carcass percentage. It was hypothesized that PGPR inclusion in the diet of broilers would improve the growth of broiler by enhancing the nutrient digestibility and this effect might be influenced by fat type.
A total of 720, day-old male broiler chicks were procured from a local hatchery. Chicks were divided into 12 treatments in such a way that each treatment had six replicates and each replicate had ten chicks. The duration of experimental period was 35 days. Flushing was done with the help of sugar solution (1kg sugar/5L water) on first day of experiment. Brooding temperature was set at 95 °F for first week. Temperature was decreased by 5° F every week until it reached at 75 °F. During the experimental period it was ensured that all birds received feed and water ad libitum. All vaccination schedule was practiced according to the suggestion of a veterinarian. The diets were corn-soybean based and formulated to meet or exceed the nutrient requirement of growing broiler as recommended by NRC 2004. All the ingredients used in the formulation of the experimental diets were supplied by commercial feed mill (Five Star Feeds Pvt. Ltd. Gujranwala, Pakistan). The ingredient data used in the diet formulation were taken from Brazilian tables for Poultry and Swine. All diets were formulated on digestible amino acids (AA) basis keeping lysine as reference AA. Experiment was divided into three dietary phases that were starter phase, grower phase and finisher phase as shown in table 1. The starter dietary phase was consisted of 0-8 days. The grower dietary phase was consisted of 9-21 days while finisher dietary phase was consisted of 22-35 days. The experimental protocol was approved by synopsis committee University of Veterinary and Animal Sciences, Lahore. Experimental procedures were followed by the guidelines and code of practice of University of Veterinary and Animal Sciences, Lahore. Permission of all experiment procedures were granted by ethical approval committee of University of Veterinary and Animal Sciences, Lahore. Birds were ensured free from hunger and thirst as described in previous research of animals (Aziz ur Rahman et al., 2017;Rahman et al., 2019).

Performance parameters
To measure the FI, growth rate and performance parameters standard procedures were adopted as described in recent study (Sharif et al., 2018). In brief, chicks and offered feed were weighed by pen at day 1, 21 and 35 of experiment. Feed intake was calculated, BWG and FCR were measured for the overall period.

Fecal samples
From days 35 to 37, fecal samples were collected from each pen by total collection method as described in the literature (Wang et al., 2008). In brief, a plastic sheet was spread in each pen before the start of digestibility trial. After every 24h, total feces were collected from each pen carefully. Contaminants such as scales, feathers, down, straws, and other fine dust particle were removed. Collected samples were packed in sealed plastic bags. Sealed plastic bags were stored at -30 ºC in refrigerator until further analysis. Furthermore, collected samples were grounded in grinder having 0.5-mm sieve. Grounded samples were further analyzed for chemical analysis as described in recent studies (Hussain et al., 2018a;Hussain et al., 2018b;Muhammad et al., 2016;Xia et al., 2018).

Nutrient digestibilities determination
For determination of digestibilities of nutrients, collected feed and excreta samples were analyzed for dry matter (DM) and crude fat determination. Dry matter and crude fat were determined using the protocol of AOAC (1995). The resulting values were used to calculate the DM and crude fat digestiblities as described in the recent studies (Anjum et al., 2019; Keles et al., 2019;Sharif et al., 2018;Tiwana et al., 2019;).

Carcass and meat quality parameters determination
For determination of carcass and meat quality parameters standard procedures were followed as described in literature. In brief, two broilers were arbitrarily selected from each replicate within a treatment to measure live BW at day 35 of the trial. After slaughtering and depluming of feathers, head, viscera, and shanks were separated. Then portioning of the carcass was done to obtain the weight of breast, legs, live weight, carcass weight, thigh meat yield, and breast meat yield. Similarly, meat obtained was used for meat quality parameters determination.

Statistical analysis
Collected data were analyzed to check the significance of the treatments by using standard statistical procedure. In brief, data were subjected to ANOVA using the GLM procedure of SPSS. The models included main effects of fat sources (soy oil, poultry oil, and oxidized oil) and PGPR inclusion (0, 0.025%, 0.035% and 0.045%), and their interactions. Each pen was considered an experimental unit.

Growth performance
Results for growth performance are shown in table 2. Results revealed that fat source has effect on BWG and FCR in both starter and grower periods. Body weight gain was higher (p<0.05) for birds which were on a basal diet containing vegetable oil as compared to other diets both in starter and overall trial. Similarly, birds showed better FCR (p<0.05) which were on basal diet containing vegetable oil as compared to other fat sources both in starter and overall trial. Results also

Nutrient digestibility
Results of nutrient digestibility are presented in table 3. Results revealed main effects for fat source on crude fat and DM digestibility. The birds showed better digestibility (p<0.05) for both crude fat and DM which were on a basal diet containing vegetable oil as compared to other diets. Results also showed main effects for PGPR level on DM and crude fat digestibility. Birds showed poorest DM and crude fat digestibility (p<0.05) at PGPR inclusion level of 0. There were PGPR by fat source significant interactions observed on crude fat and DM digestiblities (p<0.05). PGPR by fat source interactions showed that supplementation

Meat quality parameters
Results of meat quality parameters are showed in table 4. Results showed no main effects of fat sources and PGPR levels on the quality parameters of meat

DISCUSSION
The purpose of this experiment was to check the effects of PGPR inclusion in the diet of broiler on the FI, BWG, nutrient digestibility, carcass parameters, and meat quality. The other objective of current study was to optimize the level of PGPR on different fat sources in the diet of broilers. The results in the current study supported the hypothesis that fat sources in the diet of broiler influence the performance of broilers. The results in this study also supported the hypothesis that PGPR supplementation would enhance the performance of broiler chickens by increasing the nutrient digestibility.
In the overall trial, it was observed that fat sources changed the performance of the birds in term of BW and FCR. Birds gained more BW and had a better FCR when fed a diet contained soy oil. Perforamnce results of current study were similar with the findings of .  reported that broiler fed vegetable oil sources diet perform better as compare Sittiya J, Yamauchi K, Nimanong W, Thongwittaya N eRBCA-2019eRBCA- -1158 to broiler on a diet contained animal sources fat. Other researchers also reported similar findings (Chung et al., 1993;Dänicke et al., 1997;Tancharoenrat et al., 2013;Zollitsch et al., 1997). In broiler production, it is generally considered that broilers perform better on diet contained vegetable oil sources (Chung et al., 1993;Dänicke et al., 1997;Tancharoenrat et al., 2013;Zollitsch et al., 1997). Chung et al. (1993) reported that broilers received a diet contained vegetable oil gained more weight in starter phase as compared to broilers received a diet contained animals fat sources. Chung et al. (1993) also reported that broilers had better FCR on a diet contained sunflower oil as compared to those broilers received a diet contained tallow. Dänicke et al. (1997) also observed better BW and FCR in broilers fed soy oil diets than in those broilers that were fed feed contained tallow as the energy source. However, in the current study lowest BW and FCR was observed in the birds contained oxidized oils which was expected due to presence of aldehydes, ketones, esters, and polymerized oils in oxidized oils that reduce fat retention and energy value of the diet (Engberg et al., 1996). Our findings are also supported by the results of Tavárez et al. (2011) who observed that oxidized oil in the feed of broiler reduce BW.

Effect of Fat Sources and Emulsifier Levels in Broiler Diets on Performance, Nutrient Digestibility, and Carcass Parameters
Current study results revealed that increasing the level of PGPR in diet contained soy oil as fat source improved the FCR in starter phase. Furthermore, increasing the level of PGPR in diet contained soy oil as fat source improved both FCR and BW in the overall trial. Our findings are similar with the findings of Upadhaya et al. (2017) who observed a strong positive correlation between external emulsifier contents in the feed of broilers and BW gain of broilers. Furthermore, Upadhaya et al. (2017) also reported a strong negative correlation between external emulsifier contents in the feed of broiler and FCR. The improvement in gain in BW and better feed efficiency observed during the starter as well as the overall period of current experiment was due to the inclusion of external emulsifier in the feed of broilers. Emulsifier is known to improve performance by digestion of fats and support birds to overcome the inefficiency of lipase before 40 days of age in broilers (Tancharoenrat et al., 2013). Lower potential to synthesis and secretes bile salts in young broilers results in lower digestibility of fats and poor performance of growing broiler (Noy & Sklan 1998;Upadhaya et al., 2017). Broiler at an early age had less fat digestion capacity as compared to mature birds (Tancharoenrat et al., 2013). However, the inclusion of external emulsifier or synthetic emulsifier in the feed of broiler improve fat digestion and absorption in young chickens (Alzawqari et al., 2011;Dierick & Decuypere 2004;Maisonnier et al., 2003;Upadhaya et al., 2017;Zaefarian et al., 2015;Zhao et al., 2015). It has also been reported that inclusion of external emulsifier or synthetic emulsifier in the feed of broiler improve production performance in broilers (Alzawqari et al., 2011;Dierick & Decuypere 2004;Maisonnier et al., 2003;Upadhaya et al., 2017;Zaefarian et al., 2015;Zhao et al., 2015). Thus, in the current study, the inclusion of different levels of external emulsifier (PGPR) in the feed of broilers was expected to enhance the digestibility of dietary fat irrespective of fat sources. In the current study, the digestibility of DM and crude fat was improved with the increase in the inclusion levels of external emulsifier which is in agreement with a study of Upadhaya et al. (2017) who stated that increasing the level of emulsifier enhance the DM and crude fat digestibility of the diet. Similarly,  also observed improved DM and fat digestibility in broilers fed diet had external emulsifier (glycerol polyethylene glycol ricinoleate) @ of 1% and 2% of added fat. Upadhaya et al. (2017) observed a positive correlation between external emulsifier contents in the feed of broiler and DM and fat digestibilities. Other researchers also reported that different external or synthetic emulsifiers such as lysophospholipid and 1, 3 diacylglycerol improve fat digestibility when a basal ratio of broilers and weaning pigs was supplemented with graded levels of emulsifier (Upadhaya et al., 2016;Upadhaya et al., 2017;Zhao et al., 2015). In the recent study of Upadhaya et al. (2017), it was observed that DM digestibility was strongly correlated with fat digestibility. Current study result of DM digestibility and fat digestibility proved the findings Upadhaya et al. (2017) that DM digestibility and fat digestibility had strong correlation. In our study, higher digestiblities of DM and fat was the reason of improved growth performance of broilers. However, in the current study, fat sources and emulsifier did not influence the carcass and meat parameters of broilers. Our findings of carcass and meat parameters are similar with the results of previous researchers (Upadhaya et al., 2016;Upadhaya et al., 2017;Zhao et al., 2015).

CONCLUSION
Based on the results, it is concluded that PGPR supplementation in fat sources improved the body weight, feed conversion ratio, digestibility of crude fat and dry matter in broilers. However, supplementation of PGPR @ 0.035% in basal diet contained soy oil showed comparatively higher performance than other fat sources in growing broilers. Sittiya J, Yamauchi K, Nimanong W, Thongwittaya N