Effects of dietary CLA supplementation, parity and different concentrate levels before calving on immunoglobulin G1, G2 and M concentrations in dairy cows.

Peripartal dairy cows exhibit a higher susceptibility for infectious diseases, which might be linked to the negative energy balance occurring at the onset of lactation. A dietary supplementation of conjugated linoleic acids (CLA) may reduce milk fat yield and subsequently lower the energy deficit. The utilization of immunoglobulins (Ig) for colostrogenesis might impair humoral immunity in peripartal dairy cows; therefore this study investigated the effects of a CLA supplement, parity and different dietary energy levels on plasma and colostrum IgG1, IgG2 and IgM levels in dairy cows and their calves. Blood samples were collected from 64 cows from 21days before until 56days after parturition and colostrum samples for the first 3days of lactation. Plasma immunoglobulin concentrations of 19 calves were determined before colostrum uptake. Neither plasma IgG1, nor IgG2 levels were affected by CLA or dietary energy level. However, immunoglobulin levels were affected by parity. Heifers possessed the lowest IgG1 concentrations. IgG2 concentrations were highest in cows with 2 lactations prior to parturition and in heifers after parturition. Plasma IgM levels were characterized by a sharp decrease 3days prior to parturition and were scarcely affected by the feeding regimen or parity. Generally, immunoglobulin levels appear to be mostly independent from the peripartal energy balance of the cows and are not influenced by dietary CLA. However, pronounced differences among parities for IgG1 and IgG2 were revealed which should be further evaluated.

Determination of IgG and IgM levels in sera of newborn calves until the 10th day of life by ELISA and description of their correlation to total plasma protein concentration and GGT activity.

The aim of this study was the determination of IgG and IgM concentrations in sera of 15 vital and healthy calves from the day of birth to the 10th day of life using two ELISAs exclusively developed for this purpose. We investigated if and to which extent the sera profiles were correlated with antibody levels in the colostral milk administered, with GGT activity and with total plasma protein content. Due to the assays' high sensitivity, traces of IgG and IgM in calf sera could be determined prior to the first uptake of the foremilk. Throughout the colostrum administration period until the 12th living hour, IgG and IgM levels remarkably increased (P < 0.0001).The correlation between IgG concentrations in sera determined 24 h post natum and the IgG content of the colostrum administered was highly significant (P < 0.001; r = 0.851), while the correlation of seral IgM levels 24 h post natum and the IgM content of the foremilk was significant (P = 0.009; r = 0.651). The sum of the IgG and IgM concentrations in calf serum 24 h post natum was significantly correlated with the neonatal plasma protein level (P = 0.01; r = 0.642). With P = 0.012; r = 0.629 and P = 0.029; r = 0.561 respectively, there was also a significant correlation between the subjects' IgG and IgM concentrations at 24 h post natum and the GGT activity in calf serum. By looking at individual cases, it became evident that the administration of colostrum containing maximum or minimum immunoglobulin concentrations does not necessarily result in the respective sera immunoglobulin concentrations. From these findings, as well as from the fact that numerous subjects displayed their highest IgG and IgM sera concentrations well after the gut closure, we conclude that individually diverse resorption patterns are in place which cannot be characterized by immunoglobulin measurements only. The determination of the total plasma protein content or GGT activity in calf serum at 24 h post natum only give a rough idea about the actual immunoglobulin supply of the calves, since for the individual subject no conclusion could be drawn to the extent of immunoglobulin concentrations.