Report: Deliverable 2.2.2 Passive transfer of immunity from cows to calves and antibodies in nursing cows’ milk

The transfer of sufficient immunoglobulin G (IgG) to the neonatal calf through colostrum is essential to provide the calf with immunological protection and resistance against disease. Studies on the efficiency of colstrum intake and levels of IgG absorption in calves reared with cow contact are contradictory . On-farm trials were conducted in Switzerland (CH) and France (FR) to test if (1) passive transfer of immunity from cows to calves and (2) if immune (IgG) and antimicrobial (lactoferrin content=LF) parameters in dairy cows’ milk would change by nursing. Calves’ plasma and milk from cows being milked and additionally suckled twice daily for 30 minutes after milking (CH) or between morning and evening milking (FR) was compared to milk from dairy cows only milked. In CH trials IgG content in calf serum did not differ between feeding groups at any observation point, but showed a clear change over time in form of a marked drop followed by an increase again. This was mainly due to the fact that colostrum mangement between suckling and teat bucket fed calves did not differ in these trials. In FR, the IgG concentration in calves’ serum was similar in the different groups and no interaction was observed with the week. The passive immunity transfer was adequate for most calves, except for 3, 2 and 4 calves (out of 14) in groups Control, Dam and Mixed respectively whose plasma IgG concentration was below the threshold of 10 g/L (Besser et al., 1991). The plasma IgG concentration decreased significantly from week 3 to 10 and was significantly higher in female than in male calves. In Swiss trials neither IgG content (mg/L) nor lactoferrin content (LF) in cows' milk differed between feeding regimes. While IgG considerably decreased after 3 weeks, LF content stayed constant, but was more variable in nursing cows. By contrast, in French trials milk IgG was significantly higher in Mixed-cows in week 3, compared to Control and Dam-cows. This finding is very surprising considering that in week 3, all Mixed and Dam cows were suckling their calves. Therefore, differences do not seem to be due to calves’ suckling. Further investigations need to be done in order to try to understand the French results. Also contrary to the Swiss results, milk LF concentration increased steadily from week 3 to 13 and in Week 13. Milk LF was significantly higher in Control cows compared to Dam and Mixed-cows. Again, this result is very surprising and does not seem to be related to calves’ suckling as in week 13, all calves were weaned in all groups. Here again, further investigation needs to be done in order to try to understand this result that could be linked to milk SCC, slightly higher in average in Control cows in week 13.