Effect Of Dietary Fat Levels On Growth Performance,Rumen Fermentation And Microbiota Of Early-weaned Lambs

Male twin Hu lambs were selected as the experimental objects in the present study using a paired experiment design.The growth performance,nutrient digestion,slaughter performance,and rumen fermentation were investigated to explore the effects of dietary fat on the growth and development of lambs during early growth and development.Changes in rumen microflora were revealed by 16 S rDNA sequencing,then the effects of fat levels on lambs were evaluated comprehensively.The physiological nutrition of lambs provides a theoretical basis and techniques for young animal cultivation.The present study covered three trails and demonstrated as follows: Experiment 1: Effect of Dietary Fat levels on Growth Performance and Serum Parameters of Early-weaned LambsThis study aimed to investigate the effects of dietary fat levels on growth and serum parameters of early-weaned male Hu lambs.Thirty pairs of heathy male twin Hu lambs were selected and randomly allotted to two groups according to the paired design.One group was fed normal fat level(NF)milk replacer(EE:15%)and starter(EE:2.8%),and the other group was fed high fat level(HF)milk replacer(EE:27%)and starter(EE:5%).Milk replacer and starter were fed to lambs from weaning to d 60.Then NF and HF groups were fed unified starter(US)form d 60 to 120.Body weight of all lambs was measured before morning feeding regularly;at 60,90 and 120 days old,blood samples were collected from jugular vein before morning feeding,and the routine indexes of serum were determined.The results are shown as follows: body weight of lambs in HF group was significantly higher than that in NF group on 30,50,90,and 120 days of age(P<0.05).DMI of lambs in HF group was significantly higher than that in NF group(P<0.05),the rate of diarrhea before weaning in HF group tended to be lower than that in NF group(0.05<P<0.01).To a certain extent,high fat diet can improve the growth performance of male Hu twin lambs pre-and post-weaning.The high fat diet could reduce the diarrhea rate before weaning under the present experimental condition.Experiment 2: Effect of Dietary Fat Levels on Nutrient Digestibility,Slaughter Traits,and Meat Quality of Early-weaned LambsThis study aimed to investigate the effects of dietary fat levels on nutrient digestibility,slaughter traits,and meat quality of early-weaned Hu male lambs.The experiment design and animals were the same as Experiment 1.The apparent nutrient digestibility of organic matter(OM),gross energy(GE),dry matter(DM),crude protein(CP),ether extract(EE)and energy metabolism related indexes were measured in metabolism trial.Slaughter performance and meat quality were measured.On 60 days of age,the apparent digestibility of OM and GE,the value of L*,cooking loss,and EE contents of meat in the HF group were higher than those in the NF group(P<0.05).On 120 days of age,the BW,LBW,EBW,HCW,and rib eye area of the lambs in the HF group were higher than those in the NF group(P<0.05).In conclusion,high dietary fat improved the growth performance and the digestibility of EE,DM,OM,GE,CP,DE,and ME on 60 days of age.It also positively affected the slaughter performance and increased the EE content of meat.Experiment 3: Effect of Dietary Fat Levels on the Rumen Fermentation,and Microbiota in LambsThis trail aimed to investigate the effects of dietary fat levels on ruminal fermentation and microbiota.The experiment design and animals were the same as Experiment 1.Nine pairs of twin lambs were selected randomly and slaughtered,and the rumen fluid was collected at 60 and 120 days of age.On 60 days of age,NH3-N and TVFA were higher in HF group than those in the NF group(P < 0.05).On 120 days of age,the rumen fermentation parameters and microbial abundance had no significantly different(P > 0.05).The Proteobacteria and Fibrobacteres phyla and the genus Alloprevotella and Succinivibrio were advantages bacteria.This study demonstrated on 60 days age that high fat diet can affect the the abundance of several groups of rumen bacteria in rumen,such as significantly increasing phyla Proteobacteria and Fibrobacteres,and genera of Succinivibrio,Alloprevotella,and Saccharofermentans,but significantly decreasing genera of Clostridium IV,Dialister,Roseburia,and Butyrivibrio.And high fat diet improved energy utilization and had effect on VFA composition.In conclusion,high fat diet before weaning could improve the growth performance and partial nutrient digestibility,slaughter performance and intramuscular fat content of lambs at 60 days of age and affect rumen fermentation and the abundance of some microbes.At the age of 120 days,the growth performance and intramuscular fat content were still higher in NF group than those in NF group,the microbial abundance in the rumen tends to be consistent.