Enhancing the selenium content of bovine milk through alteration of the form and concentration of selenium in the diet of the dairy cow

Abstract

Since estimated dietary selenium intake in the UK has declined steadily from around 60 µg day −1 in 1975 to 34 µg day −1 in 1997, there is a need to increase selenium intake from staple foods such as milk and milk products. An experiment was therefore done to investigate the relationship between dietary source and concentration of selenium and the selenium content of bovine milk. In a 3 × 3 factorial design, 90 mid-lactation Holstein dairy cows were supplemented over 8 weeks with either sodium selenite (S), a chelated selenium product (Selenium Metasolate) (C) or a selenium yeast (Sel-Plex) (Y) at three different dietary inclusion levels of 0.38 (L), 0.76 (M) and 1.14 (H) mg kg −1 dry matter (DM). Significant increases in milk selenium concentration were observed for all three sources with increasing inclusion level in the diet, but Y gave a much greater response (up to +65 µg l −1 ) than the other two sources of selenium (S and C up to +4 and +6 µg l −1 respectively). The Y source also resulted in a substantially higher apparent efficiency of transfer of selenium from diet to milk than S or C. Feeding Y at the lowest dietary concentration, and thus within the maximum level permitted under EU regulations, resulted in milk with a selenium concentration of 28 µg l −1 . If the selenium concentration of milk in the UK was increased to this value, it would, at current consumption rates, provide an extra 8.7 µg selenium day −1 , or 11 and 14% of daily recommended national intake for men and women respectively.

Iodine and selenium carry over in milk and cheese in dairy cows: effect of diet supplementation and milk yield

“…Our data showed that the above value of milk selenium concentration could be easily reached in cows fed 0.3 mg/kg DM. Givens et al (2004) did not achieve 20 mg selenium/l of milk even with dietary selenium concentrations over the maximum allowed by the 05/1459 EC Commission Regulation (European Community, 2005). …”

“…Our data showed a maximum level (about twofold higher than the control) already at day 3, with plateau at day 10 until the end of the trial (Figure 1b), whereas in previous works, the selenium concentrations in milk and plasma tend to remain at steady condition in about 1 to 2 weeks after supplementation (Heard et al, 2007) and reach their maximums in about 40 days (Conrad and Moxon, 1979). Givens et al (2004) report a linear relationship between milk and dietary selenium concentrations in which the milk selenium (mg/l) 5 8.03 1 12.04 diet selenium (mg/kg DM) with an r 2 5 0.96. This was not supported by our results where the dose response on milk selenium concentration was nonlinear in Experiment 1 and the milk yield was the only significative factor in Experiment 2.…”

“…An increase of selenium intake could benefit the health of the population (Rayman, 2002). The recommended selenium content in the dairy cow diet is 0.3 mg/kg DM (NRC, 2001) and the expected selenium content with this level in feed is 11.6 mg/l (Givens et al, 2004). Generally, bovine milk ranges between 5 and 56 mg/l (Underwood, 1971) in relation to selenium content of feeds and soil.…”

“…Generally, bovine milk ranges between 5 and 56 mg/l (Underwood, 1971) in relation to selenium content of feeds and soil. The selenium fortified feeds, either from inorganic (sodium selenite and selenate) and organic (selenized yeasts) sources, have been fed to cows to improve the milk selenium content (Knowles et al, 1999;Givens et al, 2004).…”

Selenium supplementation of lactating dairy cows: effects on milk production and total selenium content and speciation in blood, milk and cheese

“…Additionally, Se supplements of 200 mg/day have shown reduced risks in the incidences of lung, prostate and colo-rectal cancers in humans (Combs, 2001a). Rayman (2000 and2004) reported that between 1975 and 1995 Se intakes within the UK decreased from around 60 to 34 mg per person/ day, which is approximately 50% of the recommended daily intake (Givens et al, 2004).…”