Study Of The Effects Of Low-protein Diets With Different Levels On Digestible Energy,lysine And Tryptophan In Growing Pigs

In this study,growing pigs were used to study of the effects of low-protein diets with different levels of digestible energy(DE),the DLys/DE ratio,the DTrp/DLys ratio on growth performance,serum biochemical index,serum antioxidant function,fecal compounds in growing pigs,which will provide a reference for low-protein diets in growing pigs.The study included three experiments:The first experiment was conducted to study of the appropriate levels of DE on low-protein diets in growing pigs.According to the principle of similar health and weight,240 piglets(Duroc xLandracexYorkshire)about 45 kg were divided randomly into 4 treatments(half of public and sow in each treatment),Each treatment had 3 repeats with 20 piglets.The crude protein levels were 14.50%in the 4 treatments,the same levels of DLys/DE ratio were 0.54 g/MJ in each treatment.The levels of DSAA,DThr and DTrp were made up according to the ideal amino acid balance mode.The levels of DE was 13.39 MJ/kg in treatment ?.Treatments ?,? and IV were fed the diet with oil powder,the levels of DE was 13.60 MJ/kg,13.81 MJ/kg and 14.02 MJ/kg respectively.The second experiment was conducted to study the appropriate levels of DLys/DE ratio on low-protein diets in growing pigs.240 piglets about 45 kg were randomly into 4 treatments with 3 replicates per treatment and 20 piglets per replicate.The crude protein levels were 14.50%in the 4 treatments,the most appropriate level of DE was 13.81 MJ/kg.The levels of DLys/DE ratio were 0.54 g/MJ,0.57 g/MJ,0.60 g/MJ,0.63 g/MJ respectively.According the ideal amino acid balance mode to make up the levels of DSAA,DThr and DTrp.The third experiment was conducted to study the appropriate levels of DTrp/DLys ratio on low-protein diets in growing pigs.240 piglets about 45 kg were randomly into 4 treatments with 3 replicates per treatment and 20 piglets per replicate.The crude protein levels were 14.50%in the 4 treatments,the most appropriate level of DLys/DE ratio was 0.63 g/MJ.The levels of DTrp/DLys ratio were 16%,18%,20%,22%respectively.The first experiment results showed that compared with treatments ? and ?,the daily gain of growing pigs,the content of BLU and TG,the activity of T-SOD in the treatments ? and ? were increased significantly(P<0.05);the activity of AKP was increased very significantly(P<0.01);the F/G and GOT were decreased significantly(P<0.05);the content of nitrogen was decreased very significantly(P<0.01).Compared with treatments ?,the activity of GPT in the treatments ? and ?were reduced significantly(P<0.05);the activity of GPT in the treatments ? was reduced very significantly(P<0.01);the activity of CAT in treatments ?,?,?was increased significantly(P<0.05);the content of calcium in treatments III,?was reduced significantly(P<0.05).Compared with treatments ?,?,?,the activity of GOT in treatments IV was reduced significantly(P<0.05);the content of MDA in treatments IV was significantly lower than that of the other three treatments(P<0.05);the content of TP and the activity of T-AOC in treatments IV were increased significantly(P<0.05);the content of MDA in treatments III were significantly lower than that of treatments ? and ?(P<0.05).The appropriate levels of dietary DE was 13.81 MJ/kg and 14.02 MJ/kg in this experiment,which can improve the level of growth in growing pigs greatly,blood indexes and so on.The second experiment results showed that compared with treatments ?,?,the level of ADG,the content of BLU,the activity of CAT in treatments ?,? were increased significantly(P<0.05);the activity of GPT,GOT and the content ofTCH?BUL?GLU were very significantly different between the other three treatments(P<0.01);the activity of T-SOD,GSH-PX and the content of nitrogen were significantly different between the other three treatments(P<0.05);the content of MDA was significantly lower than that of treatments I(P<0.05).Compared with treatments ?,the content of TP and the activity of T-AOC in treatments ?,?,?were increased very significantly(P<0.01);the content of nitrogen in treatments ?was decreased significantly(P<0.05).The results showed that the levels of DLys/DE ratio were 0.60 g/MJ and 0.63 g/MJ,which can improve the level of growth performance in growing pigs,improve some blood indexes;reduce the output of nutrient in fence and so on the appropriate levels of DLys/DE ratio were 0.63 g/MJ in this experiment.The third experiment results showed that compared with treatments ?,the level of ADG,the activity of T-AOC and T-SOD in treatments ?,?,? were increased significantly(P<0.05);the activity of GPT and the content of nitrogen were decreased significantly(P<0.05);the F/G in treatments ?,?,? were reduced significantly(P<0.05);the activity of GPT in treatments IV was reduced very significantly(P<0.01),and the content of BLU,the activity of GSH-PX in treatments? were increased very significantly(P<0.01);the content of TP in treatments ?,? were increased very significantly(P<0.01);the content of calcium in treatments?,?,? was significantly lower than that of treatments ?(P<0.05).Compared with treatments ? and ?,the activity of GOT,AKP and the content of TG,GLU were very significantly different between treatments ? and ?(P<0.01);the content of BUN in treatments ? was reduced significantly(P<0.05).The results showed that the levels of DTrp/DLys ratio were between 18%and 22%,which can improve the level of growth in growing pigs,improve the blood biochemical markers and antioxidant index,and reduce environmental pollution to some extent.the appropriate levels of DTrp/DLys ratio were 20%in this experiment.