Effect Evaluation Of Passive Immune Transfer And The Application Of Colostrum Management For Angus Beef Calves

Objective: The newborn calf survival rate is one of the key points linking the production efficiency in cattle industry.The failure of passive immune transfer(FPT)of newborn calves often leads to a significant increase in calf morbidity and mortality,affects the later growth and development of calves and even the performance of production.The introduction of Angus beef cattle in southern Xinjiang is a new thing in recent years.Compared with dairy calves,there is a paucity of research on passive immunity and related factors in Angus beef calves.In this experiment,cows’ colostrum yield and quality in an Angus beef cattle breeding farm in southern Xinjiang were measured,and the passive immunity effect of newborn calves was evaluated to provide the scientific basis for the formulation and application of calf colostrum milk management strategy.Methods: Fifteen healthy Angus primiparous and 15 third-parous cows were randomly selected,and cows were manually milked immediately after calving to determine the average yield of the first postpartum colostrum,with sample collection to determine the main nutrients,physical and chemical characters,immunoglobulin concentrations and their changes for 5days.The birth weight of the primiparous and multiparous(third)calves from above-mentioned cows was weighed and blood samples were collected to determine their physio-biochemical indicators.The serum total protein content was determined after birth without colostrum(0 h)and after colostrum intake(24 h ～ 36 h).Results: The average colostrum production of primiparous cows(637 ± 381 m L)was significantly lower than the average colostrum production of third parity cows(2421 ± 987 m L)(P < 0.01).The colostrum milk protein,milk fat,non-fat milk solids,lactose and ash contents of primiparous cows were 7.88%,6.46%,20.56%,11.3% and 1.63%,respectively;colostrum density,conductivity and p H were 1.07 g/cm3,4.45 m S/cm and 7.07,while the colostrum milk protein content,milk fat content,non-fat milk solids content,lactose content and ash content of the third parity cows were: 6.48%,5.64%,17.71%,9.4 % and 1.24%;colostrum density,conductivity and p H were 1.06%,5.62% and 6.94,respectively.Among them,colostrum milk protein,non-fat milk solids,lactose,ash content and density of primiparous cows were significantly higher than those of colostrum of third parity cows(P <0.01).The conductivity of colostrum of primiparous cows was significantly lower than that of colostrum of multiparous cows(P < 0.01).The concentration of immunoglobulin in the colostrum of primiparous and third parity cows showed a downward trend within 5 days,and the concentration decreased by 50% at about 21 h.The concentrations of immunoglobulins in the first lactation of primiparous cows and third parity cows after calving were 28.72 ± 3.53%and 26.24 ± 6.75%,respectively.The pass rate of immunoglobulin in colostrum of primiparous cows was 93.33%,and the pass rate of immunoglobulin in colostrum of multiparous cows was 86.67%.The passive immunization failure rate of newborn calves was 33.3%,while the passive immunization failure rate of postnatal calves was 25%.The mean body weight of first-born calves(31.15 ± 4.08 kg)was significantly lower than that of multiparous calves(37.74 ± 5.14kg)(P < 0.05).The birth weight of the passively immunized failure calves was significantly higher than that of the passively immunized succeed calves(P < 0.01),and the average birth weight of the former(35.97 ± 5.42 kg)was significantly higher than that of the latter(29.6 ±2.96 kg)(P < 0.01).The globulin content of the passively immunized calves was significantly higher than that of the passively immunized failed calves(P < 0.01),and the red blood cell distribution width of the passively immunized failed calves was significantly higher than that of the passively immunized calves(P < 0.05).Conclusions: The above findings indicate that the main reason for the failure of passive immunity of Angus beef calves may be insufficient colostrum intake of newborn calves caused by insufficient colostrum production of primiparous cows,and the higher passive immunity failure rate is associated with lower birth weight of newborn calves.Therefore,based on the results of this experiment,the strategy of the colostrum management for newborn Angus calves is formulated and applied in production practice in this farm showing important practical guiding value and significance.