Effects Of Tannin Acid On Lactation Performance,Nitrogen Metabolism,rumen Fermentation In Early-Lactating Holstein Cows

This study was conducted to examine the effect of quebracho-chestnut tannin extracts(QTE,tannic acid≥73%)supplementation on lactation performance,blood indicators,nitrogen utilization,rumen fermentation and microbial diversity in early-lactating Holstein cows.Sixty Holstein dairy cows in early lactation(77.8 ± 3.23 DIM)were used in a randomized complete design.Cows blocked by parity(2.54 ± 0.21),milk production(46.8± 1.92 kg/d),and DIM(77.8±3.23 d)were assigned to 1 of 4 treatments.Cows were fed QTE at doses of 0,10,20,or 30 g/d per head for 56 d.1 Effects on lactation performance of dairy cows.Although dry matter intake,fatand protein-corrected milk(FPCM),and feed efficiency by FPCM were not affected by QTE supplementation(P>0.05),the yield of actual milk increased linearly(P<0.05)and feed efficiency by milk tended to increase linearly(P=0.07)with increasing QTE supplementation in overall.The yield of actual milk in the QTE30 treatment was higher than the CON treatment,QTE10 treatment,and QTE20 treatment(P<0.05)2 Effects on milk composition of dairy cows.At d 56,the yields of milk protein and milk protein concentration increased linearly with increasing QTE doses(P<0.05),whereas milk urea nitrogen(MUN)concentration decreased linearly(P<0.05).The milk protein concentration in the QTE30 treatment was higher than the CON treatment and QTE10 treatment(P<0.05),and the QTE20 treatment was higher than the CON treatment(P<0.05).Somatic Cell Score(SCS)tended to decrease linearly(P=0.08).Overall,the yield of milk protein increased linearly with increasing QTE doses(P<0.05),and the yields of milk protein in the QTE30 treatment were higher than in the CON treatment and QTE10 treatment(P<0.05).The MUN concentration decreased linearly(P<0.05).The SCS tended to decrease linearly(P=0.07).The yields of milk fat tended to increase linearly(P=0.09).Supplementation of QTE did not affect milk fat percentage,lactose percentage,lactose yield,and total solids percentage(P>0.05).3 Effects on feed efficiency of dairy cows.Total-tract apparent digestibility of nutrients was not affected by QTE supplementation(P>0.05).4 Effects on blood biochemical indexes and antioxidant capacity index of dairy cows.Supplementation of QTE did not affect blood concentration of glucose,total protein,albumin,nonesterified fatty acid,β-hydroxybutyric acid,creatinine,aspartate aminotransferase,and alanine aminotransferase(P>0.05),whereas total antioxidant capacity(T-AOC)and activity of super oxide dismutase(SOD)and glutathione peroxidase(GSHPx)increased linearly with increasing QTE supplementation(P<0.05),the T-AOC in the QTE30 treatment and QTE20 treatment was higher than the CON treatment(P<0.05).Blood concentration of urea nitrogen(BUN)and malondialdehyde(MDA)decreased linearly(P<0.05),and the BUN concentration in the CON treatment was higher than the QTE20 treatment and QTE30 treatment at d 56(P<0.05).Overall,the T-AOC and activity of SOD increased linearly with increasing QTE supplementation(P<0.05),the T-AOC in the QTE30 treatment and QTE20 treatment was higher than in the CON treatment(P<0.05).The activity of GSH-Px tended to increase linearly(P=0.08),and the BUN concentration tended to decrease linearly(P=0.07).5 Effects on rumen fermentation parameters of dairy cow.At d 56,the molar proportion of propionate tended to increase linearly with increasing QTE doses(P=0.07),whereas ammonia concentration tended to decrease linearly(P=0.06).Overall,the molar proportion of propionate increased linearly with increasing QTE doses(P<0.05),whereas ammonia concentration and the molar proportion of butyrate tended to decrease linearly(P=0.06).Ruminal pH and total volatile fatty acid ammonia concentration were not affected by QTE supplementation.6 Effects on rumen microbial diversity of dairy cow.Supplementation of QTE did not affect Faith_pd、Pielou_e and Simpson index(P>0.05).At d 28,the relative abundance of Bacteroidetes at the phylum level tended to increase linearly with increasing QTE doses(P=0.06),whereas the F/B ratio decreased linearly(P<0.05)and the relative abundance of Firmicutes at the phylum level tended to decreased linearly(P=0.10).Relative abundance of Prevotella and Succiniclasticum at the generic level increased linearly with increasing QTE doses(P<0.05),whereas Relative abundance of Butyrivibrio at the generic level decreased linearly(P<0.05).The relative abundance of Succiniclasticum in the QTE30 treatment was higher than in the CON treatment and QTE10 treatment(P<0.05).At d 56,the Chao1 index increased linearly with increasing QTE doses(P<0.05),whereas the Observed_species index(P=0.07)and Shannon index(P=0.09)tended to increased linearly,and the Goods_coverage index tended to decrease linearly(P=0.07).The relative abundance of Proteobacteria at the phylum level and relative abundance of Butyrivibrio at the generic level decreased linearly(P<0.05),whereas the relative abundance of Prevotella and Succiniclasticum at the generic level increased linearly with increasing QTE doses(P<0.05).In overall,the Chao1,Observed_species,and Shannon index tended to increase linearly with increasing QTE doses(P<0.05).Relative abundance of Bacteroidetes at the phylum level increased linearly with increasing QTE doses(P<0.05),whereas the relative abundance of Proteobacteria at the generic level and F/B ratio decreased linearly(P<0.05).7 Effects on nitrogen utilization efficiency of dairy cow.At d 56,the yields of milk N and microbial N increased linearly with increasing QTE doses(P<0.05),whereas milk N/N intake ratio(P=0.06),total purine derivatives(P=0.06)and allantoin(P=0.09)tended to increase linearly,and the yields of urea-N and urine N,and urine N/N intake ratio decreased linearly(P<0.05),and the yields of urea-N in the CON treatment was higher than the QTE30 treatment(P<0.05).Overall,the yields of milk N and microbial N,urine N/N intake ratio,and total purine derivatives increased linearly with increasing QTE doses(P<0.05),and the yields of microbial N in the QTE30 treatment were higher than the CON treatment and QTE10 treatment(P<0.05).The yields of urea-N(P=0.06)and urine N(P=0.10),and urine N/N intake ratio(P=0.10)tended to decrease linearly with increasing QTE doses(P<0.05),whereas uric acid and allantoin(P=0.06)tended to increase linearly.Supplementation of QTE did not affect N intake,urine output,urea-N/N intake ratio,fecal output,fecal N,fecal N/N intake ratio,manure N,and manure N/N intake ratio(P>0.05).In conclusion,feeding QTE to early lactating cows improved lactation performance by optimizing rumen fermentation parameters and microbial diversity,increasing antioxidative status and nitrogen efficiency without affecting DMI and nutrient digestibility.The optimal QTE dose should be 30 g/d per head.