Concentrations of antimicrobial components in milk at dry off and postpartum and their relationships to new high somatic cell counts at quarter level in dairy cows.

We investigated the antimicrobial components in cow milk at dry off and postpartum and their contribution in preventing new high SCC at quarter level. Milk samples from 72 quarters of 19 lactating cows were collected at last milking before dry off and at 7 d after parturition. Milk yield of each cow was recorded and SCC, IgG, IgA, lactoferrin, lingual antimicrobial peptide (LAP), and S100A7 concentrations in each quarter milk sample were measured. The postpartum milk yield was significantly higher than that at dry off. The IgG, IgA and lactoferrin concentrations in milk at dry off were significantly higher than those at postpartum, whereas the LAP concentration was lower. Quarters with SCC < 300 000 cells/ml at both dry off and postpartum were classified as persistent low SCC (PL) whereas those that rose above that same threshold postpartum were classified as new high SCC (NH). At dry off, IgG and LAP concentrations in milk were significantly higher in PL than in NH. These results suggest that high LAP concentrations during the dry period may contribute toward the prevention of new high SCC.

Effect of low milking frequency on the concentration of antimicrobial proteins in goat milk.

This study examined the effects of low frequency milking on the concentrations of antimicrobial components in goat milk. Sixteen goats were divided into two groups of eight each: milking once every 2 d three times (for six days, three times group) or five times (for 10 days, five times group). On other days, milking was performed once daily. Milk was collected, and milk yield, somatic cell count (SCC), and the concentrations of some antimicrobial proteins such as lactoferrin (LF), S100A7, IgA, and sodium ions (Na+) in milk were measured. Milk yield significantly decreased in both the groups during the low-milking frequency period, followed by an increase above the low frequency milking period in both groups. In contrast, SCC and LF concentrations in milk increased in both groups during the low frequency milking period. The concentration of S100A7 in milk temporarily decreased after the low frequency milking period, followed by a significant increase. The S100A7 concentration during this period was higher in the five times group than in the three times group. These results indicated that low frequency milking induced a gradual decrease in milk yield and a concomitant increase in antimicrobial components, such as LF and S100A7, in milk. This increase in the antimicrobial components may be useful in preventing mastitis.

Effects of frequent teat stimulation on antimicrobial component production in mammary glands of lactating goats.

Various antimicrobial components, such as lactoferrin, S100 calcium-binding protein A7 (S100A7), and IgA, produced by epithelial cells and leukocytes in lactating mammary glands are important for host defense against invading pathogens. Increase in milking frequency enhances milk yield in ruminants and implies an increase in frequency of teat stimulation. However, the influence of frequent teat stimulation on the production of antimicrobial components remains unclear. In this study, we investigated the effect of frequent teat stimulation, with and without milk removal, on the lactoferrin, S100A7, and IgA concentrations in milk of lactating Shiba goats in Japan. The lactoferrin, S100A7, and IgA concentrations in milk were measured using ELISA. We found that lactoferrin concentration decreased by frequent teat stimulation with milk removal, although concentrations of IgA and S100A7 increased. Frequent teat stimulation without milk removal also altered the lactoferrin, IgA, and S100A7 concentrations. Furthermore, frequent teat stimulation increased IL-22 concentration, which has been reported to upregulate S100A7 production in cultured human keratinocytes. Thus, these findings indicate that frequent teat stimulation, with or without milk removal, affects antimicrobial components in milk and may be useful for the prevention and treatment of mastitis in ruminants.