Increasing Selenium Concentration in Milk: Effects of Amount of Selenium from Yeast and Cereal Grain Supplements

Abstract

Two experiments were conducted to establish responses in milk Se concentrations in grazing dairy cows to different amounts of dietary Se yeast, and to determine the effects of the Se concentration of the basal diet. The hypothesis tested was that the response in milk, blood, and tissue Se concentrations to supplemental Se would not be affected by whether the Se was from the basal diet or from Se yeast. In addition, by conducting a similar experiment in either early (spring; experiment 1) or late (autumn; experiment 2) lactation, we hypothesized that different Se input-output relationships would result. Both 6-wk experiments involved 60 multiparous Holstein-Friesian cows, all of which had calved in spring. They were allocated to 1 of 10 dietary Se treatments that included 2 types of crushed triticale grain (low Se, approximately 165 microg of Se/kg of DM; or high Se, approximately 580 microg/kg of DM) fed at 4 kg of DM/d, and 1 kg of DM/d of pellets formulated to carry 5 quantities of Se yeast (0, 4, 8, 12, or 16 mg of Se). Daily total Se intakes ranged from <2 to >18 mg/cow in both experiments. Milk Se concentrations plateaued after 15 and 7 d of supplementation in experiments 1 and 2, respectively, and then remained at plateau concentrations. Average milk Se concentrations for the plateau period increased as the amount of Se yeast increased, and low- and high-Se grain treatments were different at all quantities of Se yeast, although there was a tendency for this difference to diminish at the greatest concentrations of yeast. There were significant positive, linear relationships between Se intake and the concentrations of Se in milk, which were not affected by the source of Se, and the relationships were similar for both experiments. Therefore, the output of Se in milk in experiment 1 was greater than that in experiment 2 because the milk yield of the cows in early lactation was greater. The estimated proportions of Se partitioned to destinations other than milk and feces increased with the amount of Se in the diet and were greater in experiment 2 than in experiment 1, a result that was supported by Se concentrations in whole blood and plasma and in semitendinosus muscle tissue. If high-Se products are to be produced for human nutrition, it is important to be able to develop feeding systems that produce milk with consistent and predictable Se concentrations so that products can consistently meet specifications. The results indicate that this objective is achievable.

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

“…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.…”

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

“…Although these results confirm earlier studies by numerous workers including Givens et al (2004), Juniper et al (2006) and Heard et al (2007), milk yield responses to Se supplementation have been noted in New Zealand from cows grazing low-Se pastures (Grace et al, 1997). However, in the current study there was a significant (P , 0.05) positive linear effect of increasing Se supplied in the form of SY.…”

“…Recent work by Heard et al (2007) emphasised that if the objective was to produce highSe products for human consumption then it was important that they are produced in a consistent and predictable manner. While their work showed a very rapid increase in milk Se concentration, which peaked after 7 to 15 days of Se supplementation, the current study in which Se analyses started only after 28 days of supplementation showed that milk Se concentration peaked much later, between 84 and 112 days after treatment initiation.…”

“…Numerous studies have now shown that when compared with SS, the use of SY increased the Se concentration in bovine milk (Knowles et al, 1999;Ortman and Pehrson, 1999;Weiss, 2005;Juniper et al, 2006;Heard et al, 2007) and caprine milk and cheese (Caja et al, 2007), and has been suggested as one potential route for increasing Se intake in humans in areas where it is below optimum.…”

Microencapsulated sodium selenite supplementation in dairy cows: effects on selenium status

“…In this study, CTR group cows had an higher milk Se/ingested Se ratio compared with the 3.2% reported by Calamari et al (2010). On the other hand, average Se secretion in milk of cows supplemented with selenized yeast is expected to be 10-18% depending on lactation stage, milk yield, protein yield, and Se intake (Heard et al, 2007;Juniper et al, 2008; Figure 1 Behavior of total Se in milk (a), plasma (b), and feces (c) in dairy cows that received diets containing either sodium selenite providing Se at 0.3 mg/kg DM (CTR) or microencapsulated sodium selenite providing Se at 0.3 mg/kg and 0.5 mg/kg DM (0.3M and 0.5M, respectively) and selenized yeast providing Se at 0.3 mg/kg and 0.5 mg/ kg DM (0.3Y and 0.5Y, respectively). Values are least squares means, and vertical bars represent s.e.…”