Effects Of Dietary Protein Levels And Rumen Protected Amino Acids On Growth And Fattening Performance,Nutrient Digestion And Rumen Fermentation Of Hu Sheep

Protein is the most important nutrient for animals.Due to the unique rumen system of ruminants,the metabolic process of protein in ruminants is more complicated than that in monogastric animals.Ruminants can make use of non-protein nitrogen?NPN?,which cannot be used by monogastric animals,and have a special urea cycle mechanism to make use of inferior protein feeds.However,ruminants do not have a high utilization rate of nitrogen,resulting in more waste of protein resources.At present,there is no data to support the research on dietary protein level and the improvement of nitrogen utilization in Hu sheep.Therefore,this research by setting different protein levels of diet and adding rumen bypass methionine?RPM?,bypass lysine?RPL?on the fattening sheep growth performance research,for fattening sheep diet protein levels and amino acids by adding rumen bypass will provide a scientific basis for improving the nitrogen utilization in ruminants and theoretical guidance.This experiment mainly includes two parts:Experiment 1:Effects of different protein levels of dietary on the growth performance,digestion metabolism,serum parameters,rumen microbial composition and fermentation parameters of fattening Hu sheep.A total of fifty-four male Hu sheep?32.25±2.5 kg?with the age of three months were randomly divided into 3 treatments according to the principle of similar age and weight,each treatment have eighteen sheep,three dietary crude protein?CP?levels were11.5%,14.0%,and 16.5%,respectively.The period for pre-test was 7 days,while the period for formal test was 63 days.The results showed that:1.There was no difference in the initial body weight of experimental sheep?P>0.05?.The final body weight of Hu sheep in 11.5%CP group was significantly lower than the 14.0%CP group and the 16.5%CP group?P<0.05?,the feed efficiency of 11.5%CP group was significantly higher than the 16.5%CP group?P<0.05?.2.The dry matter,organic matter,acid detergent fiber in 16.5%CP group was significantly higher than 11.5%CP group?P<0.05?.Nitrogen intake and urine nitrogen output of 11.5%CP group were significantly lower than that of 14.0%CP group and16.5%CP group?P<0.05?.The apparent digestibility of nitrogen in 16.5%CP group was significantly higher than that in 11.5%CP group and 14.0%CP group?P<0.05?.Nitrogen deposition in 11.5%CP group was significantly lower than that in 16.5%CP group?P<0.05?.3.The serum albumin,albumin/globulin of 16.5%CP group was significantly lower than 11.5%CP and 14.0%CP group?P<0.05?,but the globulin was significantly higher than the other groups?P<0.05?.The serum urea nitrogen of each group was significantly different?P<0.05?.4.The ammonia nitrogen in the rumen fluid of the 11.5%CP group was significantly lower than that of the 14.0%CP and 16.5%CP group?P<0.001?.Rumen pH has an increasing trend with increasing dietary protein levels?P<0.1?.With the increase of CP level in the diet,the ratio of isovalerate tended to increase?P=0.098?.The contents of Ruminococcus flavefaciens of 11.5%CP group was significantly lower than 14.0%CP group?P<0.05?,16.5%CP group was not significantly different from11.5%CP group and 14.0%CP group.Experiment 2:Effects of rumen protected amino acid added by dietary on the growth performance,digestion metabolism,blood indexes and rumen fermentation parameters of fattening Hu sheep.A total of seventy-two male Hu sheep?31.91±2.36 kg?with the age of three months were randomly divided into 4 treatments according to the principle of similar age and weight,each treatment have eighteen sheep.The treatment groups were:basal diet group?no soybean meal diet-NSM?,basal diet with rumen protected lysine group?RPL?,basal diet with rumen protected methionine group?RPM?,mixed protected amino acid group?RPLM?,meanwhile,14%CP group that in experiment 1 was used as control group?CON?.The period for pre-test was 7 days,while the period for formal test was 63 days.The results showed that:1.There was no significant difference in initial weight,DMI and F/G among the treatment groups,while the final weight of the group with rumen-protected amino acids added had a trend of increased?P=0.943?,and the RPL and RPM groups had significantly higher ADG than the CON and NSM groups?P<0.05?.2.There was no significant difference in the apparent digestibility of DM,OM and ADF in each treatment group?P>0.05?.The digestibility of NDF in RPLM group was significantly higher than that in RPL group?P<0.05?.There was no significant difference in nitrogen intake,fecal nitrogen,urinary nitrogen,deposition nitrogen and nitrogen deposition rate among the treatment groups?P>0.05?.Compared with the other groups,the apparent digestibility of nitrogen in the group with rumen-protected amino acids was trend to be increased?P=0.093?.3.The blood glucose content of RPLM group was higher than that of other groups?P<0.05?,and there was no significant difference in other serum indexes among treatment groups?P>0.05?.4.The live weight before slaughter of RPL and RPM group was significantly higher than that of CON and NSM group?P<0.05?,there was no significant difference in live weight before slaughter between RPLM group and other groups.There was an increasing trend of carcass weight in the diet group supplemented with rumen-protected amino acids?P=0.071?.There were no significant differences among treatment groups in slaughter rate,total rumen weight,rumen tissue weight and tail fat weight.5.There was no significant difference in rumen pH between treatment groups?P>0.05?.The concentration of N-NH₃ in the rumen of the CON group was significantly higher than that of the other treatment groups?P<0.05?.The concentration of TVFA and the ratio of acetic acid,propionic acid,butyric acid,valeric acid,isobutyric acid and isovaleric acid were not affected in each treatment group,and there was no significant effect on the A:P?P>0.05?.In summary,dietary protein levels significantly affected animal performance.Particles diet add by-pass amino acid can improve the growth performance and slaughter performance of animals,does not affect the rumen fermentation,instructions on replacing soybean meal as protein sources of adding rumen bypass methionine and lysine diet can reduce the negative impact of animals caused by insufficient soybean meal,and to a certain extent,can improve the production performance of animal.