Effects Of Coated Folic Acid And Coated Copper Sulfate On Performance,ruminal Fermentation And Expression Of Genes Related To Protein Metabolism In Dairy Bulls

The objective of this study was to determine the effects of coated folic acid(CFA)and coated copper sulfate(CCS)on performance,ruminal fermentation and expression of genes related to protein metabolism in dairy bulls.The experimental design is as follows: in Exp.1,sixteen Holstein bulls(15 ± 0.9 months of age)were randomly assigned to one of three treatments: control(without Cu addition),CS(with 8 mg/kg dry matter [DM] of Cu from CS)and CCS(with 8 mg/kg DM of Cu from CCS),respectively.Basal diet contained 7.63 mg/kg DM of Cu.In Exp.2,Sixteen Holstein dairy bulls(12 months of age)were assigned to one of four groups in a randomized experimental design with a 2(0 [CFA-] or 4 mg folic acid as RPFA per kg dietary dry matter [CFA+])× 2(0 [CCS-] or 10 mg copper as RPCS per kg dietary dry matter[CCS+])factorial arrangement.in Exp.1,dietary Cu addition did not affect feed DM intake and average daily gain but elevated(P<0.05)nutrient apparent digestibility in bulls.Ruminal p H reduced(P<0.05)but total volatile fatty acids(VFA)content and acetate to propionate ratio elevated(P<0.05)with Cu addition.The higher activity of xylanase,pectinase and α-amylase and copies of Ruminococcus.flavefaciens 和Butyrivibro fibrisolvens,and lower laccase activity for CCS addition.Liver Cu concentration elevated(P<0.05)but hepatic expression of mammalian target of rapamycin reduced(P<0.05)with Cu addition.Intramuscular expression of mammalian target of rapamycin was lower(P<0.05)for CCS addition than control.Liver Cu concentration was greater(P<0.05)but hepatic and intramuscular expression of mammalian target were reduced(P<0.05)for CCS supplementation than for CS addition.In Exp.2,The higher average daily gain,nutrient digestibility,rumen total VFA content,acetate to propionate ratio,enzyme activity,bacteria populations and Serum growth axis hormone concentration were observed for CFA or CCS addition.the CFA × CCS interaction was significant(P<0.05)for ruminal ammonia N concentration,activities of xylanase and α-amylase,population of Ruminococcus.flavefaciens,Fibrobacter succinogenes Butyrivibro fibrisolvens and Ruminobacter amylophilus,excretion of urinary urinary allantoin and total purine derivatives(PD)and concentration of serous albumin,total cholesterol,and acetoacetic acid.The decreased magnitude of ruminal ammonia N concentration and serous total cholesterol concentration for bulls receiving no CFA addition were bigger than bulls receiving CFA addition,but it is inverse for ruminal α-amylase activity and Ruminobacter amylophilus population.The increased magnitude of ruminal xylanase activity and excretion of urinary allantoin and total PD by CCS addition for bulls receiving no CFA addition were bigger than bulls receiving CFA addition,but it is inverse for population of ruminal Ruminococcus.flavefaciens,Fibrobacter succinogenes and Butyrivibro fibrisolvens and concentration of serous albumin.The decreased magnitude of serous acetoacetic acid concentration by CFA addition for bulls receiving no CCS addition was lower than bulls receiving CCS addition.In conclusion,nutrient digestion and ruminal fermentation was improved by Cu addition,but the expression levels of protein metabolism related genes were down-regulated in liver and muscle tissue with CCS supplementation compared with Cu SO4 supplementation.the higher efficiency in improving the growth performance and nutrient utilizational was not observed for the combined addition of CFA and CCS compared with CFA or CCS supplement alone in dairy bulls.