Lactoferrin and IgG levels in ovine milk throughout lactation: Correlation with milk quality parameters

The aim of this work has been to determine the levels of lactoferrin and IgG in ovine milk during the two first months of lactation and to compare with some milk quality parameters. Milk samples were collected from ewes of an Assaf flock. The levels of lactoferrin were determined by radial immunodiffusion. For this purpose, lactoferrin was isolated from ovine milk by chromatographic methods and polyclonal antibodies against it were obtained in rabbits. IgG levels were determined by a commercial sandwich ELISA. The mean concentration value of lactoferrin at the first day of lactation was 0.74 mg/ml and that for IgG of 9.25 mg/mL. The levels dropped sharply during the first three days of lactation and at the third week of lactation, the concentration in mature milk was of 0.07 mg/ml and 0.25 mg/ml for lactoferrin and IgG, respectively. There was no correlation between the levels of lactoferrin and IgG concentrations in ovine milk samples with those of total protein and bacterial count. A low positive correlation between lactoferrin and somatic cell counts (SCC) was found, which was more evident when samples were classified according to SCC levels. However, no significant differences were found with respect to IgG levels in milk samples, for high or low levels of SCC. Consequently, it seems that only high lactoferrin levels could be used as an indicator of subclinical mastitis.