| This experiment was conducted to evaluate the effects of different additives onweaning stress of calves. A total of84healthy31-day-old China Holstein calves wererandomly allocated into7groups with12calves each group. Calves in control group werereared by the feeding method of the farm, and the others in experimental group were fed onthe basis of the control group supplemented with1%sodium butyrate (SB),0.1%Bacillusnatto (BN),0.08%chromium yeast (CY),1.2%Eyquem XP (XP),1.2%Eyquem XP+1%sodium butyrate (XP+SB),1.2%Eyquem XP+0.08%chromium yeast (XP+CY). All thecalves were weaned at60d. The experiment lasted for45days. Calves were fedindividually. The results showed as follows:(1) Growth performance: At31d~60d of age, the average daily gain (ADG) of calvesin control group was0.79kg/d. Compared with the control group at60d of age, the ADGin BN group, XP group, XP+SB group and XP+CY group were increased by12.66%(P<0.01),12.66%(P<0.01),12.66%(P<0.01) and16.46%(P<0.01). At61d~75d of age,the ADG in SB group, BN group, XP group, XP+SB group and XP+CY group wereincreased by10.61%(P<0.01),16.67%(P<0.01),10.61%(P<0.01),19.70%(P<0.01),21.21%(P<0.01),31.82%(P<0.01).(2) The apparent digestibility of nutrients and diarrhea rate: The apparent digestibilityof crude protein (CP) of the calves in SB group, BN group, XP group, XP+SB group andXP+CY group were obviously higher12.09%(P<0.05) and8.14%(P<0.05),4.21%(P<0.05),10.99%(P<0.05),13.45%(P<0.05) than that in control group at60d of age; andobviously higher6.27%(P<0.05) and6.70%(P<0.05),4.90%(P<0.05),4.60%(P<0.05),9.44%(P<0.05) than that in control group at75d of age.The apparent digestibility of crude fat (EE) of the calves in experiment group wasbetter than that in control group. Thereinto the apparent digestibility of EE in BN group,XP group, XP+SB group and XP+chromium yeast group were increased by5.80%(P<0.05)and8.65%(P<0.05),7.88%(P<0.05),7.48%(P<0.05) than that in control group,respectively, at60d of age. At75d of age, the apparent digestibility of EE in SB group,BN group, XP group, XP+SB group and XP+CY group were significantly higher5.01%(P<0.05) and4.27%(P<0.05),8.90%(P<0.05),8.99%(P<0.05),10.42%(P<0.05) thanthat in control group, respectively. From apparent digestibility of the neutral detergent fiber (NDF), acid detergent fiber(ADF) of calves in each group, we knew that the apparent digestibility of NDF in CYgroup had enhanced11.93%(P<0.05) and ADF in CY group and XP+CY group hadenhanced14.74%and13.59%(P<0.01) at75d of age.During the whole trial, the diarrhea rate and the diarrhea frequency of calves inexperiment group were lower than that in control group. Compared with the control group,the diarrhea rate of calves in SB group, BN group, XP group, XP+SB group and XP+CYgroup were decreased by25.00%,37.50%,12.50%,37.50%,50.00%,62.50%, and thediarrhea frequency were decreased by44.77%,60.58%,26.28%,63.75%,78.83%,90.02%.(3) Blood Parameters: Compared with control group about the serum crotisol level,SB group, BN group, XP group, XP+SB group and XP+CY group were lower21.67%(P<0.05),33.75%(P<0.01),15.83%(P<0.05),18.07%(P<0.05),24.79%(P<0.05) and39.26%(P<0.01) at60d of age. At75d of age, they were decreased by24.05%(P<0.01),48.92%(P<0.01),36.49%(P<0.01),22.63%(P<0.01),42.82%(P<0.01) and41.88%(P<0.01).Compared with the control group, the Haptoglobin (HP) level of the SB group, BNgroup, CY group, XP group, XP+SB group and XP+CY group were decreased by10.03%(P<0.01),9.23%(P<0.01),14.27%(P<0.01),20.61%(P<0.01),29.93%(P<0.01),35.63%(P<0.01) at60d of age and decreased by9.51%(P<0.01),12.67%(P<0.01),13.23%(P<0.01),17.15%(P<0.01),27.98%(P<0.01),35.74%(P<0.01) at75d of age.The C-reactive protein (CRP) level in SB group, BN group, CY group, XP group,XP+SB group and XP+CY group were lower7.99%(P<0.01),16.91%(P<0.01),7.64%(P<0.01),18.41%(P<0.01),22.48%(P<0.01),19.48%(P<0.01) than control group at60days old. BN group, CY group, XP+SB group and XP+CY group were lower12.05%(P<0.01),9.87%(P<0.01),7.90%(P<0.01),8.39%(P<0.01) and12.67%(P<0.01) thancontrol group at75days old.(4) Indexes of rumen development: With the increase of calves age, the weight ofrumen, reticulum and abomasum were higher. Rumen weight was the greatest for calvesfrom XP+SB group and was more22.64%(P<0.05) than contol group at60d of age. AndRumen weight in XP group, XP+SB group and XP+CY group were more11.83%(P<0.01),16.18%(P<0.01),15.10%(P<0.01) than that in control group at75d of age.Compared with control group, calves from SB group, BN group, CY group, XP group,XP+SB group and XP+CY group tended to have higher rumen papillae length for42.44%(P<0.01),39.99%(P<0.01),66.52%(P<0.01),53.91%(P<0.01),77.62%(P<0.01),74.69%(P<0.01) at60d of age, and for63.70%(P<0.01),80.52%(P<0.01),55.68%(P<0.01),72.22%(P<0.01),92.42%(P<0.01),90.47%(P<0.01) at75d of age. With theage of calves increasing, the rumen papillae width and mucosa thickness were growthed, and they were higher than that of control group.The enzymes activities of rumen chyme were higher in experiment groups than incontrol group. Thereinto neutral proteinase activity in XP+CY group was significantlyhigher10.85%than that in control group at60d of age, and in SB group, BN group, CYgroup, Eyquem XP group, XP+SB group and XP+CY group were significantly higher5.84%(P<0.01),4.01%(P<0.05),3.28%(P<0.05),3.65%(P<0.05),3.65%(P<0.05),4.38%(P<0.05) than that in control group at75d of age. α-amylase activity in XP groupwas increased by1.52%(P<0.05) than control group at75d of calves age.The NH3-N concentrations in rumen were higher in experiment group than that ofcontrol group, and enhancing with age increased. Compared with the control group, theNH3-N concentration in SB group, BN group, XP group, XP+SB group and XP+CY groupwere higher33.44%(P<0.05),62.41%(P<0.01),41.84%(P<0.05),44.96%(P<0.01),41.23%(P<0.05), respectively, at60d of age, and were higher70.04%(P<0.01),131.63%(P<0.01),63.16%(P<0.01),141.85%(P<0.01) and127.90%(P<0.01), respectively, at75d of age.The acetate concentration of calves in the rumen in SB group, CY group, XP group,XP+SB group and XP+CY group were lower21.93%(P<0.05),20.23%(P<0.05),19.31%(P<0.05),25.04%(P<0.05) and27.41%(P<0.01) than that of control group at60d of age.At75d of age, the acetate concentration of calves in the rumen in XP+SB group andXP+CY group were decreased by29.65%(P<0.05) and28.64%(P<0.05) than that ofcontrol group. The butyrate concentration of calves in the rumen in BN group was more48.41%(P<0.05) than control group at60d of age. There was no significant different ofthe butyrate concentration in other groups.In summary, addition of1%SB,0.1%BN,0.08%CY,1.2%XP,1.2%XP+1%SB and1.2%XP+0.08%CY could relieve weaning stress of calves, which resulted from improvedbetter performance, decreased serum cortisol and acute phase protein concentration,stimulated rumen development. Also, addition of1.2%XP+0.08%CY had the greatesteffectiveness and followed by1.2%XP+1%SB. |
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