SYSTEMIC AVAILABILITY OF BOVINE IMMUNOGLOBULIN-G AND CHICKEN IMMUNOGLOBULIN-Y AFTER FEEDING COLOSTRUM AND EGG POWDER TO NEWBORN CALVES

In connection with a study on the prophylaxis of infectious diarrhea w ith specific egg yolk antibodies, the systemic availability of colostr al bovine immunoglobulin G (bIgG) and chicken immunoglobulin Y (IgY) a fter feeding egg powder was investigated on 26 newborn calves from 23 different farms. Blood was sampled daily and at the same day time from these calves in the first 14 days of life. During the feeding of colo strum, the mean bIgG concentration was highest at day 1 post natum wit h a value of 9.3 mg/ml serum. Thereafter, the mean bIgG level was redu ced continuously to a significant lower concentration of 4.9 mg/ml ser um at day 12 post natum and remained nearly constant at 5.2 mg/ml till to the end of the observation period. Total protein concentrations in the serum did not change and plateaued at a mean value of 56.2 mg/ml (SD 11.2). The number of colostrum meals had no significant: effect on the mean bIgG concentrations during that period. The individual varia tion of bIgG concentrations was very high on every day of the sampling period. The mean coefficient of variation was at 52.1 % (SD 5.7). Aft er having described the individual bIgG concentration curves mathemati cally with a regression curve, two groups with significantly different bIgG elimination constants (k) could be obtained. Thus in one group ( n = 10) with k-values of < -0.02 a mean half time of serum bIgG of 24. 3 days (SD 4.6) was calculated. In the other group of calves (n = 16) with elimination constants of k > -0.02, a mean half time of 68.5 days (SD 36.7) could be calculated, possibly because these calves started earlier with their endogenous bIgG production. Additionally, to 18 of these calves 20 g egg powder with an IgY concentration of 15 mg/g was Fed up to day 14. Calves had a maximal mean IgY concentration of 1.9 m u g/ml serum if egg powder feeding started already during the first 12 hours of life. Starting at a later time resulted in a significant red uction of IgY levels. For example, the mean initial IgY concentration dropped to 0.035 mu g/ml serum after having had the first egg powder a pplication between 25 and 48 hours post natum. Using the individual Ig Y elimination constant derived from a regression analysis (r(2) = 0.84 ) of the IgY concentration curve, a mean IgY half time of 5.0 days (SD 2.5) could be calculated. To prevent the absorption of heterologeous antibodies and consecutively, also to prevent a possible systemic effe ct, egg powder for prophylactic purposes in newborn calves should be f ed after the first 24, better 48 hour, post natum. Most important for the prophylactic effect of specific antibodies on infectious diarrhea is not their systemic but their high local intestinal availability.