A study on the effects of the estrous cycle on uterine fluid and blood serum immunoglobulin G (IgG) content in the cow

To investigate the IgG content and its variations in uterine fluid (UF) during the estrous cycle of the cow and to compare them with those of the blood serum (S), six pairs of serum and UF samples for each phase of the cycle selected out of 240 bovine genital tracts and blood samples were collected from Urmia abattoir. The UF samples were collected by gentle scraping of the endometrium using a curette after uterine incision and their IgG content and those of the serum were measured by single radial immuno-diffusion (SRID) assay. Serum IgG values (Mean ± SEM) were generally higher than the UF values throughout the cycle except for di-estrus (S: 38.50 ± 0.90, UF: 51.60 ± 2.10 mg mL(-1)), in which the highest values were observed in UF samples. In met-estrus the difference was not significant (S: 34.80 ± 1.80 mg mL(-1), UF: 30.80 ± 5.20 mg mL(-1)), however, in estrus the mean UF IgG value (12.50 ± 1.10 mg mL(-1)) was lower than that of the serum (31.30 ± 1.20 mg mL(-1)). In pro-estrus, the lowest values (S: 27.80 ± 1.30 mg mL(-1), UF: 9.10 ± 1.50 mg mL(-1)) were obtained. The results showed a lower IgG values in the bovine UF than those of the serum in the follicular phase of the cycle, while in di-estrus the UF IgG content was the highest, suggesting some IgG production in the uterus at this phase.