| Establish successful passive immunity,prevention of preweaning calf diarrhea(PCD)and reduction of preweaning stress are the three major events for calves’ health.PCD is the main reason for preweaning calf mortality.Hence,it is critical that the immune system neonatal calves is not developed yet.Neonatal calves must obtain immunoglobulins just after birth is a critical preventative strategy.The sufficient antibodies and established passive immunity only can only be obtained by feeding colostrum.Failure of passive immunity(FTPI)will result in decreased immunity of calves..However,there is no substantial research data on the effect of colostrum management on diarrhea in dairy industry in China.To analyze the effects of colostrum management on the growth,diarrhea and death of calves,a cross-sectional study was conducted to determine the factors affecting the growth,diarrhea and death of calves,and then a cohort study was conducted to analyze the effects of these factors on the growth,diarrhea and death of calves.The objective of this cross-sectional study was to determine the prevalence of FTPI and colostrum management of calves in Shaanxi Province.The information on the specific operations of colostrum management in the farm was collected through record review and questionnaire survey by researchers who visited the farms.The health scores and blood samples was collect from calves that were 1 to 10 days of age at the day when the researchers visited.A biochemical analyzer was used to measure the level of STP to determine passive immunity.All data were imported in STATA16 for analysis.The association between FTPI and health score was analyzed by linear regression.The association between FTPI and diarrhea was analyzed by logistic regression.From March to June 2021,researchers visited 33 dairy farms in Shaanxi.Among the 254 calves which were sampled blood,12.6% were males and 87.4% were females.The average weight and age of male calves and female calves were 39.17 kg SD = 8.00)and 4.63 d(SD = 2.54),respectively.The average STP was 6.55 g/dl(SD =1.06)and through using a cut point of ≤ 5.50 g/dl,the prevalence of FTPI was 14.8%.The occurrence of FTPI was not related to gender(OR = 1.71;95% CI = 0.53～5.47),age(OR = 0.86;95% CI = 0.70～1.05)or weight(OR = 0.99;95% CI = 0.94～1.05).The level of STP was not related to gender(β =-0.12;95% CI =-0.26～0.01)age(β =-0.09;95% CI =-0.23～0.05)or weight(β = 0.03;95% CI =-0.10～0.16).As to health scores,the age,gender,weight and FTPI were not related to respiratory(p > 0.05)or fecal consistency score(p > 0.05).From the questionnaire,the mean timing of first colostrum feeding is 1.4 h(range = 0～14 h),with farms providing an average of 3.58,2.33 and 2.81 L of colostrum at 0 to 6,6 to 12 and 12 to 24 hours after birth.Almost all farms(26;78.8%)used colostrum from other dams as their main source of colostrum.The common method of feeding colostrum was an esophageal tube(22;66.7%).Some farms(7;21.2%)reported that the male calf colostrum management is different,including sources,amount of colostrum and no colostrum.The results showed that compared with related research reports,the prevalence of FTPI in calves in Shaanxi is lower,and no association between FTPI and calf health scores was found.To further investigate the effects of colostrum management on diarrhea,growth and death of calves,the objective of this prospective cohort study was to investigate the risk factors associated with calf diarrhea and determine the impact of diarrhea on ADG,diarrhea and death of preweaning calf.A total of 972 calves were enrolled at birth and followed until 30 days of age at commercial farms in shaanxi provice.Calves had fecal consistency scored on a daily basis and had blood samples collected at 24 to 48 hours of life for determination of the levels of STP using a Biochemical Analyzer.All data were collected in STATA16 for analysis.To evaluate factors associated with the development of diarrhea,growth and death of calves a Linear regression model,Multivariable logistic regression model and Cox proportional hazards model was built.32.1% of calves had diarrhea as defined by a fecal score of 2or 3 over the experimental period.With respect to growth from birth to 30 days of age,the ADG was 0.78 ± 0.13 kg/day.The mean level of STP was 7.04 ± 0.76 g/dl and with only 2.03%(19/953)of calves having failed transfer of passive immunity(STP ≤5.5 g/dl).In terms of diarrhea,it was found that for every 1 g/dl increase in STP,the odds of diarrhea decreased(OR = 0.78;95% CI = 0.65～0.95).In addition,calves born in May(OR = 0.47;95% CI = 0.33～0.67)and June(OR = 0.32;95% CI =0.22～0.46)had a lower ratio of diarrhea compared to calves born in April.It was found that calves with diarrhea had a lower ADG(-0.11 kg/ day;95% CI =-0.12～-0.09)compared to calves without diarrhea.In terms of mortality,mortality was significantly associated with STP(P = 0.036).This study illustrated that calves with passive immune failure had a higher risk of death and were more likely to develop diarrhea,suggesting that diarrhea is also association with ADG and the birth month of calves. |
