Effect of milking frequency on milk immunoglobulin concentration (IgG, IgM and IgA) and chitotriosidase activity in Majorera goats

Abstract

Eleven goats belonging to Majorera breed were used during the early lactation to determine the milk IgG, IgM and IgA concentration and the Chitotriosidase (ChT) activity in milk at three different milking frequencies. The goats were machine milked during 5 weeks, at week 1 and 5 once daily, at week 2 and 4 twice daily and at week 3, three times a day. Every week, milk samples (50 ml) were collected from each goat after the first morning milking. The samples were aliquoted and storage at -80°C until immunoglobulins concentration and ChT activity were analyzed. To determine the IgG, IgM and IgA concentration a commercial goat ELISA kit was used and fluorimetric assay was performed to measure the ChT activity. Milk IgG and IgM concentration decreased as milking frequency increased, showing an enhance trend when the milking frequency returned to milking once daily. IgA concentration increased throughout the experimental period from 0.03 mg/ml (week 1) to 0.09 mg/ml (week 4). ChT activity decreased from week 1 (782.90 nmol/ml/h) to week 5 (651.18 nmol/ml/h). In conclusion, milking frequency affected the milk immune status, although different evolutions have been observed. Findings in the present report might help in the discussion about the susceptibility of mastitis when milking frequency is increased. More experiments will be necessary to evaluate long term effects of milking frequency on milk immune status.