Effects Of Emulsifier In Two Metabolizable Energy Diets On Growth Performance And Nutrients Availability In Broilers

As natural emulsifier, soyabean lecithin emulsifier could make up the lack of biliation and emulsify the fat, which was benefit for the digestive absorption of broilers. Two trails was conducted to evaluate the effect of soyabean lecithin emulsifier, energy levels and their interaction on growth performance, slaughter performance and nutrient utilization in the study. The underlying reasons was investigated by the serum biochemical parameters, digestive physiology and digestive enzymes active. The proper addition of soyabean lecithin in22-42d broiler feed was also conducted in further study.Experiment1:Effects of emulsifier in two metabolizable energy diets on Growth Performance and Nutrients Availability of broilers from day1to49This study was conducted to evaluate the effects of emulsifier in two metabolizable energy(ME) levels diets on performance, digestive physiology and serum biochemical parameters of broilers. A total of960Cobb500male broilers were randomly allocated into1of4treatments by a2×2factorial design in a49-day experiment. Each treatment included6replicates and40birds per replicates. The metabolizable energy(ME) were12.13(adequate energy group) and11.92(reduced-energy group) MJ/kg for the starter (1-21d),12.96(adequate energy group) and12.65(reduced-energy group) MJ/kg for the grower (22-49d). The levels of emulsifier were0and265mg/kg for the starter,0and400mg/kg for the grower. The nutrients digestibility experiment was conducted at the end of growth experiment.The results showed that compared with the adequate energy group, decreasing the dietary energy significantly decreased the body weight gain (BWG) from day1to21(P<0.01) and increased the ratio of feed to body weight gain (F/G) from day1to21and from day1to49(P<0.05). Emulsifier added in feed significantly decreased the F/G from day1to21and day1to49(P<0.05). There was no significant difference for F/G in the reduced-energy diet containing emulsifier and in the adequate energy group from day1to 49. Dietary energy levels and emulsifier did not affect the carcass properties.The addition of emulsifier in adequate energy diet increased the dressing percentage,yield of carcass,breast yield and hamstrings yield.The addition of emulsifier was tend to decreased the abdominal fat and skin-folds.Emulsifier supplementation siginificantly improved the content of serum free fatty acid on day21and day49(P<0.01), and siginificantly increased serum total bile acid conyrnyd on day21(P<0.05).There was a tendency in increasing apparent digestibility of ether extract and gross energy (P>0.05). High dietary energy level had no siginificant effect on the apparent digestibility of crude protein, but tend to increase the apparent digestibility of dry matter, ether extract and gross energy (P>0.05).Broilers in the group of adequate energy diet supplemented with emulsifier showed a highest hepeatic lipase activity on day49. Compared with reduced-energy diet, adequate energy diet supplemented with emulsifier siginificantly increased the lipase activity of pancreas on day21and49(P<0.05). Emulsifier supplementation siginificantly increased activities of hepeatic LPL on day21(P<0.05),the activity of HL on day21and day49(P<0.05), and the activity of LPL+HL on day21and day49(P<0.01). The activity of lipase in duodenum and jejunum was highest in group of adequate energy diet added with emulsifier on day21, which was highest in group of reduced-energy diet added with emulsifier on day49. The height of villus in the jejunum was highest in group of low energy diet added with emulsifier on day21. The interaction between dietary energy and emulsifier significantly affected the villus height in jejunum (P=0.05). Emusifier supplementation increased the villus height in the jejunum.Experiment2:Effects of Emulsifier levels on Growth Performance and Nutrients digestibility of Broilers from day22to42A total of one thousand22-d old Cobb male broilers were randomly allocated into5groups with5replicates per groups and40birds per replicates. The levels of emulsifier were0,200,350,500and650mg/kg. The metabolizable energy(ME) werel2.65MJ/kg design in a21-day experiment (22～42d),The nutrients digestibility experiment was conducted at the end of growth experiment.There was no significant difference on growth performance, slaughter performance and nutrient utilization at22-42d with the addition of emulsifier. Along with the increased addition of emulsifier, the growth performance was tend to be improved. The addition of 200mg/kg,350mg/kg,650mg/kg emulsifier increased average body weight by4.15%.5.64%、7.37%at42d, increased average body weight gain by5.13%、9.31%、12.42%, decreased feed:gain ratio by1.65%、5.35%.4.94%, and with the lowest feed:gain ratio with the addition of350mg/kg emulsifier.In conclusion, the addition of emulsifier in diets of grower period could improve the performance significantly and improve apparent digestibility of nutrients of broilers. The addition of265mg/kg emulsifier in the starter diet and400mg/kg emulsifier in the grower diet could dcrease the dietary energy level for0.2and0.3MJ/kg, respectively, and reduce the ratio of fat in diet. The result of experiment2indicated the optimal addition levels of emulsifier in diet of grower broiler was350mg/kg.