t i l Production Efficiency, Nutrient Utilization and Intestinal Histology of Broilers Fed on Energy Diluted Diet Supplemented with Lipase and Bile Acids

This study was carried out to determine the efficacy of lipase and emulsifier + lipase in broilers reared on energy diluted diet. Five hundred and twenty birds were divided into 8 treatments groups with 5 replicates of 13 birds in each. Total 8 diets viz., PC (Positive control), NC1 (Negative control 1; 75 Kcal/kg reduced energy), NC1L (NC1 + lipase at 0.015%), NC1LB (NC1 + lipase at 0.015% + bile acids at 0.05%), NC2 (Negative control 2; 150 Kcal/kg reduced energy), NC2L (NC2 + lipase at 0.015%), NC2LB (NC2 + lipase at 0.015% + bile acids at 0.05%) and NC2 (2LB) (NC2 + 2x (lipase at 0.03% + bile acids at 0.1%)) were formulated. Weight gain, feed intake (FI), protien efficiency ratio (PER), energy efficiency ratio (EER), mortality percentage and food conversion ratio (FCR) were similar (P > 0.05) by addition of lipase and bile acids in energy diluted diets during starter phase in broiler chicks. However, birds of NC1L group had higher European production efficiency factor (EPEF) than other treatments. Weight gain, PER, EER and EPEF were higher (P < 0.05) in birds of NC1LB group and lower (P < 0.05) in birds of NC2 and NC2L group. However, FCR was better (P < 0.05) in birds of NC1LB and NC2 (2LB) group and birds of NC2 group had poor (P < 0.05) FCR. Villus height of ilium and villus surface area was higher (P < 0.05) in birds of NC1LB and lower (P < 0.05) villus height and less (P < 0.05) villus surface area were recorded in NC2 group. In conclusion addition of lipase and bile acids as emulsifier in combination form had improved production efficiency and increased villous surface area in broilers reared on 75 kcal reduced energy diet.


INTRODUCTION
E nergy is a main nutrient of diet, which is necessary for proper growth and functioning of body (Cho et al., 2012). Energy content of broilers diet is increased by the use of lipids in their diet (Abudabos, 2014). Digestibility of fat in broilers body is limited due to limited digestive ability by birds, although it compromises the function of promoting growth (Siyal et al., 2017). Poor breakdown and absorption of lipids have been observed in broiler chickens during early age (Ravindran et al., 2016). Use of fat at higher level in broilers diet reduces other nutrient intake resulting in poor growth. Production of pancreatic lipase and bile acids is low at early age of birds due to immature development of GIT track (Classen, 2017). Fat utilization is not efficient in broilers due to less lipase activity until its reach optimum level between 40 to 56 d of age (Pantaya et al., 2020). Therefore, it is very important to improve fat utilization in broilers for better utilization of fat.
Fat utilization in broiler chickens is improved by using lecithin and lysolecithin as emulsifier for decades (Maisonnier et al., 2003). Bile acids are being used as a dietary emulsifier in poultry production (Parsaie et al., 2007). Utilization of bile acids during early stage in chicks has more potential to improve fat breakdown and absorption than older ones (Alzawqari et al., 2011). Exogenous lipase also improves the physiological capacity of GIT track in poultry. Lipase production is widespread among yeasts having different properties. Using Yarrowia lipolytica lipase improved FCR and had no adverse effect on feed intake O n l i n e

F i r s t A r t i c l e
for 42 days' period (Wang et al., 2018). Addition of dietary lipase in broilers fed low-fat diet resulted in a better response on growth performance and fat utilization (Hu et al., 2018). Meat quality and health status of broilers were also improved with supplementing emulsifier or multi-enzyme (Mohammadigheisar et al., 2018). Feeding low energy diets to broiler chickens resulted in reduced performance but supplementing emulsifier (bile acids) or lipase in reduced energy diets alleviated the negative effects. Therefore, this study was planned to evaluate the effect of lipase and bile acids on growth performance, nutrient utilization and intestinal histology in a reduced energy diet.

MATERIALS AND METHODS
The present study was carried out at Research House, Animal Nutrition Center, University of Agriculture, Faisalabad with prior approval from the Board of Advanced Studies and Research of the University of Agriculture, Faisalabad via letter no. 15497-500.

House preparation
House was cleaned, disinfected and fumigated to reduce the infectious count. The experimental trial was conducted under all hygienic and standard conditions.

Data collection on growth performance
Data on the growth parameters were recorded weekly using following formulas.
Feed intake = Feed offered -Feed refused FCR = Feed intake (g) / Weight gain (g) Protein efficiency ratio (PER) = Weight gain / Protein intake

Statistical analysis
Data were subjected to analysis using analysis of variance by completely randomized design with the help of Minitab 17. Tukey's test was used to compare mean (Steel et al., 1997).

Growth performance Starter phases
Weight gain, FI, PER, EER, mortality percentage and FCR were similar (P > 0.05) by addition of lipase and bile acids in energy diluted diets during starter phase in broiler chicks. However, birds of NC1L group had greater (P < 0.05) EPEF than other treatments (Table III).

Finisher Phase
Weight gain, PER, EER and EPEF were higher in birds of NC1LB group and lower (P < 0.05) in birds of NC2 and NC2L group. However, FCR was improved (P < 0.05) in birds of NC1LB and NC2 (2LB) group and birds of NC2 group had poor (P < 0.05) FCR (Table IV). Mortality percentage was higher in birds of NC2 group.

DISCUSSION
Weight gain was higher (P < 0.05) in birds of NC1L and NC1LB and lower (P < 0.05) in birds of NC2 and LC2L groups. This might be due to that bile acid and Lipase increase the energy value of oil used in this experiment. Results are in line with the Kamran et al. (2020) who concluded that use of polyglycerol polyricinoleate at 0.025, 0.035 and 0.045% in soy oil based diet had improved weight gain and FCR in broilers. Liu et al. (2020) reported that weight gain and FCR were improved in birds receiving 97% de-oiled lecithin in basal diet than control group. Allahyari-Bake and Jahanian (2017) observed that addition of emulsifier in broilers diet containing soy-free fatty acids had higher (P < 0.05) feed intake and improved (P < 0.05) weight gain than control. Also, use of 0.1% emulsifier in broilers diet had improved FCR as compared to 0 and 0.05% inclusion of emulsifier, while, feed consumption and body weight were not affected (Zosangpuii et al., 2015). Results are in consistent with the outcome of Hu et al. (2018) who revealed that the use of 0.03% lipase in broilers fed lower energy diet had improved (P < 0.05) FCR, however, body weight gain was not affected (P > 0.05). Soya lecithin (50% of oil in basal diet) and lipase (100000 IU/ton) had higher (P < 0.05) weight gain, feed consumption and better FCR (Nagargoje et al., 2016). Maisonnier et al. (2003) showed that the addition of 0.3% bile salts had better (P<0.05) body weight gain (440 vs 399 g) during 7-21 days in broiler chickens. However, Al-Marzooqi and Leeson (2000) evaluated the different levels of supplementary lipase enzyme (0, 0.37%, 0.75%, 1.12%) and reported that with increasing level of lipase enzyme, FCR was improved (P<0.05).
In contrast, Wang et al. (2018) tested the effect of dietary lipase supplementation of three levels of lipase enzyme (0, 4U/g and 6U/g) on broilers and concluded that lipase did not have any effect on growth rate and final BW in broilers during 42 days. Nazir (2014) tested the effect of dietary supplementation of three levels of bile acids (0, 0.03% and 0.06%) on broilers and concluded that bile acids did not affect growth rate in broilers during 35 days. Lipase addition at 0.02% did not influence the production performance of broilers fed different sources of oil (beef tallow and canola oil) (Meng et al., 2004).
Villus height and villus surface area were higher (P < 0.05) in birds of NC1LB, whereas, lower villus height and villus surface area were recorded in NC2 group. Villus width, VH:CD and VH:VW were not affected by lipase alone or in combination with bile acid in energy diluted diet. This might be due to that bile acid reduces the destruction of intestinal villi results in increased surface area and absorption of nutrient when fed with lipase.
Results are in according with the outcome of Hu et al. (2018) who concluded that addition of lipase had higher (P < 0.05) villus height and VH:CD in broilers reared to 100 kcal/kg reduce energy diet. Brautigan et al. (2017) who showed that addition of lyso-lecithin.in broilers diet increased villus height and width of jejunum of broilers. Chen et al. (2014) showed that lipase at 9,000 U/kg feed had higher (P < 0.05) VH, VH:CD and reduced CD in small intestine. Results are not in line with the Lai et al. (2018) who showed that addition of bile acid in broilers diet had no effect on hematological parameters of small intestine. Zosangpuii et al. (2015) reported that emulsifier (glycerol polyethylene glycol ricinoleate: GPGR) at 0.04% had no effect on villi length of duodenum, jejunum and ilium because to low level of emulsifier used in broilers diet.

CONCLUSION
It can be concluded that birds fed 75 and 150 kcal/ kg reduced energy diet had lower growth performance, however, addition of lipase and bile acids as emulsifier in combination form had improved production efficiency, nutrient utilization and intestinal histology in broilers reared on 75 kcal reduced energy diet.