Effects Of Different Dietary Energy Levels And Feeding Ways On Production Performance And Abdominal Fat Deposition Of Broilers

This experiment was conducted to investigate the effects of dietary energy levels and feeding ways on the production performance and abdominal fat deposition in broilers. Preliminarily explored the relation of dietary energy levels and abdominal fat deposition, comparison the feed ad libtum (FAL) with feed restriction (FR), to provide the references for modifying dietary energy levels and reducing abdominal fat in production.In this experiment 1344 from same batch, healthy,1-day-old Liangfenghua female broiler chickens were randomly allotted into 8 groups, each group consisted of 6 replicates with 15 broilers each. The experimental period lasted 56 days, and divided into early (1～28 d) and late (29～56 d) feeding periods. The experiment designed 4 dietary energy levels. Among Group 1 to Group 4:Group 1 was the control group, and fed the normal energy level basal diet (the dietary metabolic energy levels of two periods respectively were 12.15 MJ/kg and 12.77 MJ/kg); Group 2, Group 3 and Group 4 were test groups, respectively fed on the basal diet reduced ME 0.21 MJ/kg,0.42 MJ/kg and 0.63 MJ/kg, but other nutrient levels remained same, Group 1 to Group 4 were used FAL during the whole experimental period. Among Group 5 to Group 8:The diets of Group 5 to Group 8 were respectively same one-one corresponding to the diets of Group 1 to Group 4, while towards the late period Group 5 to Group 8 were used FR, artificially limited fed 90% of diet compare with Group 1 to Group 4.The results showed that:1) With the decrease of dietary energy levels,average daily feed intake (ADFI) and feed/gain (F/G) very significantly increased (P<0.01), but average daily gain (ADG) had no significant difference (P>0.05), that had no adverse effect on the growth of broilers, and when decreased 0.42 MJ/kg dietary energy had the best growth performance; In late phase,90% quantity feed restriction (FR) could significantly reduce the ADG of broilers (P<0.05), and very significantly reduce ADFI and F/G (P<0.01), so FR had a certain promotion effect on feed conversion ratio increasing; There were no interactions between the dietary energy levels and feeding ways on the production performance of broilers (P>0.05).2) The dietary energy levels had significant impact on the dressed percentage (DP) of broilers (P=0.01), and when decreased 0.42 MJ/kg dietary energy could obtain the higher slaughter performance; The late feed restriction (LFR) significantly decreased percentage of half-eviscerated yield (PHE) and percentage of eviscerated yield (PE) of broilers (P<0.05), significantly increased the percentage of thigh muscle (PTM) (P<0.05); The dietary energy levels and feeding ways only had interaction effect on DP (P<0.05).3) The percentage of abdominal fat (PAF) of broilers offered descending firstly than upgrade latter tendency with the decrease of energy levels, but did not differ significantly (P>0.05); LFR had a tendency to reduce PAF (P>0.05); Dietary energy levels and feeding ways had no interaction effect on PAF (P>0.05).4) LFR and interaction very significantly improved the bursa of fabricius index (P<0.01).5) In late period,dietary energy levels and feeding ways had interaction effect on GLU (P<0.05); with the decrease of energy levels, the content of serum TG closed to significantly increased (P=0.056), the content of serum INS as well (P=0.059); LFR significantly increased the content of serum GH (P<0.05).6) The reduction of dietary energy levels obviously inhibited the expression of FAS gene mRNA in liver issue(P<0.05); The interaction had significantly effect on the activity of FAS (P<0.05); LFR significantly decreased the activity of HSL in AF issue (P<0.05),the influence that LFR acted on the expression of LPL gene mRNA in AF tissue was closed to significance (P=0.094). Through the experiment, we can get the following conclusion:within a certain range, limiting broilers energy intake has no significant effect on the production performance, and tends to decrease abdominal fat deposition as well.we suggest that, under the condition of FAL,the dietary energy level is 11.73 MJ/kg in early period, and 12.35 MJ/kg in late period, so that does not affect the production performance and has certain effect on reduction abdominal fat deposition of Liangfenghua broilers.