Effects Of Low Protein Diet On Growth Performance,Rumen Fermentation Function And Methane Emissions Of Liuyang Black Goat

Properly reducing the amount of protein in the feed is one of the ways to effectively reduce the cost of breeding,but reducing the protein content in the feed may have negative effect on the animals.This study was designed to investigate some of the apparent and physical changes that might bright to the ruminant livestock by reducing the amount of feed protein.Twenty-four female Liuyang black goats with good health at the age of 1 year(19.6±3.55 kg)were rando mLy divided into two groups,which were control group(high protein diet,10.77%of CP)and low protein diet group(5.52%of CP).Goats were kept in single cage,the trial sustained 70d,including 25d as pre-feeding period,45d for positive feeding,digestion and metabolism test were done during the 31d-35d in the positive feeding period,feed sa MCPles,fecal sa MCPles and urine sa MCPles were collected to determine the relevant apparent digestion indexes of goats(dry matter intake,dry matter digestibility,organic matter digestibility,total energy digestibility,NDF digestibility,ADF digestibility,protein digestibility,starch digestibility),respiratory metabolism test was carried out for 36d-45d,methane emission was measured,followed by slaughter test,rumen fluid and rumen fermentation gas were collected,46d-47d for living rumen fluid collection,and the rumen fermentation function parameters and the concentration of rumen fermentation gas were determined.The results show:1)There was no significant difference in dry matter intake,dry matter digestibility,organic matter digestibility,total energy digestibility,NDF digestibility and ADF digestibility for low protein diet group and control group.The protein digestibility of the low protein group was significantly lower than that of the control group,and the starch digestibility was higher than that of-the control group;2)There was no significant difference in the average daily body weight gains between two groups.The low protein group tended to decrease the feed conversion than the control group(p = 0.09),indicating that the low protein diet was against the digestion and absorption function of goats.There was no significant difference in body weight and slaughter rate between the low protein group and the control group;3)There was no significant difference in ruminal pH between the low protein group and the control group,but the low protein group lowered the ammonia concentration(p=0.0001),and the molar proportions of acetate and valerate(p=0.012).There was no significant difference in propionate,butyrate,iso-butyrate and iso-valerate acid,and the total volatile fatty acid concentration decreased by low protein group(p=0.04).The concentration of microbial protein was not affected;4)The volume of rumen dissolved gas extracted from the control group and the low protein group,dissolved H2 in the rumen fluid,and the concentration of dissolved CH4 was not affected by the low protein diet.There was no difference in rumen headspace H2 and CH4 concentration,indicating that the low protein diet had no significant effect on the rumen fermentation gas;5)Co MCPared with the control group,the daily CH4 emission(g/d),CH4/DMI,CH4/NDFD,CH4/GEI and CH4/ADFD was not altered by the low protein group.However,the low protein group tended to decrease CH4/DMD(p=0.08)and CH4/OMD(p=0.08),and decreased CH4/CPD significantly(p=0.001).In summary,this study shows that the low protein diet had no significant effect on the growth performance of Liuyang black goats,but had a negative i MCPact on protein digestibility.With the decrease of dietary protein concentration,the concentration of ammonia,total volatile fatty acids,acetate and valerate in the rumen were significantly reduced,indicating that the low protein diet had a negative effect on the rumen fermentation function of Liuyang black goat.Although there was no significant difference in CH4 daily emissions,the CH4/DMD and CH4/OMD decreased,and CH4/CPD were decreased by low protein diet,indicating that low protein diet can effectively reduce CH4 emissions from Liuyang black goats.In conclusion,the low protein diet had no significant effect on the growth performance,total tract digestibility and rumen fermentation function of Liuyang black goats,but can inhibit CH4 emissions effectively.