Lactoferrin is a component of milk whey, valuable for its properties as an iron-binding, bacteriostatic and anti-bacterial protein. Commonly, lactoferrin concentrations are high in colostrum and in late-lactation milk (Nonnecke & Smith, 1984). In particular, the lactoferrin content of mammary secretion is markedly increased during mammary involution when expression of the lactoferrin gene is initiated in milk-engorged, secretory alveoli (Molenaar et al., 1996). A feature of once-daily milking (OAD) is the accelerated regression of the udder that leads to an increased rate of decline in milk yield as lactation progresses (Carruthers et al., 1993). This accelerated regression and attenuation of lactation is particularly notable in some cows, although others appear relatively unaffected. In addition, there are changes in milk composition commensurate with changes that normally occur at drying-off. This suggests that milk lactoferrin concentration could be enhanced during OAD. Milk lactoferrin content has not been measured previously in cows in which milking frequency has been changed. Eight cows (mixed breeds) in mid-lactation, grazing rye-grass/white clover pasture at No. 1 Dairy, Dexcel (Ruakura) were used in this study. They were milked twice daily (TAD) from parturition and underwent a period of three days of OAD beginning at day 123±4 of lactation, on average. Mean milk SCC before treatment was 178±53 x 103 cells/ml. Milk samples were taken before, during and after OAD and assayed for lactoferrin using an ELISA method (Bethyl Laboratories, Montgomery, Texas, USA.) Milk yield and composition were also recorded.
Proceedings of the New Zealand Society of Animal Production, Volume 62, Palmerston North, 225-226, 2002
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