Bioavailability of rumen bacterial Selenium in mice using tissue uptake technique

Abstract

A tissue uptake experiment was conducted to determine the bioavailability of rumen bacterial Selenium (Se) in mice. The donor animal was wether fed a diet containing 0.2 mg Se/kg dietary dry matter (DM). Ruminal fluid was collected 2 h postprandially. Bacterial-rich precipitate was obtained by differential centrifugation of the ruminal fluids. This was later freeze-dried and mixed in the diet to be used in feeding the mice experiment. Thirty growing female mice with a body wt (mean +/- SD) of 21.4 +/- 0.74 g were housed in plastic cages (5 mice/cage) and allotted equally to three dietary treatments. Diet 1 and Diet 2 were formulated based on AIN-76, except that no Se supplementation in the form of selenite was made in the former. In Diet 3, rumen bacterial matter was 20% of the diet, which gave an equivalent of 0.1 mg Se/kg dietary DM. The other two diets, Diet 1 and Diet 2, had an Se content of 0.025 and 0.1 mg/kg dietary DM, respectively. A 7-d feeding commenced after 7 d of acclimatization of the semipurified diet. Results showed that those mice fed an Se- (selenite) supplemented diet (Diet 2) had higher (P < 0.05) tissue Se concentrations than those mice fed the other two diets. No statistical differences were observed on various tissue Se concentrations between Diet 1 and Diet 3, although the latter diet had higher values. Kidney and liver had the highest Se concentrations compared to the other tissues. This study concludes that bacterial Se collected from the rumen of wether is not fully available for absorption in the intestine of the mice.

Utilization of microbial selenium collected from the rumen of sheep

“…This result is similar to the findings of Serra et al (1997), who reported higher Se concentrations in some vital organs of rats fed bacterial Se than in those supplemented with selenite or selenate. Likewise, Ortman and Pehrson (1999) observed the same positive effects of bacterial-Se supplementation in elevating the blood Se concentration of cattle, but not with selenate or selenite.…”

“…Therefore, Se accumulation is highest in the liver and kidney, followed by other organs such as the spleen, pancreas and lung where Se retention is quite high. Conversely, the nerve cells and brain are not known to accumulate and retain significant amounts of Se (McDowell, 1985;Serra et al, 1997). Table 6 shows the significantly higher Se concentration in the kidney of rats in the Se-supplemented groups, which tends to support the previous observation of Serra et al (1997).…”

“…Conversely, the nerve cells and brain are not known to accumulate and retain significant amounts of Se (McDowell, 1985;Serra et al, 1997). Table 6 shows the significantly higher Se concentration in the kidney of rats in the Se-supplemented groups, which tends to support the previous observation of Serra et al (1997). The loss of Se through the urine is highest in rats fed ISe.…”

“…The addition of selenite to the diet of sheep produced 0.40 g microbial matter Se per kg rumen matter, which is comparable to the 0.45 mg microbial Se · kg -1 DM from our previous study (Fujihara and Ichinohe, 2012). This value is twice the 0.2 mg Se · kg -1 DM reported by Serra et al (1997), despite the similar feeding rate of selenite to the host animal.…”

Utilization of protozoal selenium in young goats

“…The reduction-reactions happening in the rumen could also contribute to the low turnover of Se (Cousins and Cairney, 1961;Peterson and Spedding, 1963;Harrison and Conrad, 1984). Although there was an increasing evidence of Se trapping by microbial rumen population, our earlier study showed that bacterial-Se collected from the rumen of wethers was not fully available for absorption in the intestine of mice (Serra et al, 1997). If bacterial-Se had low bioavailability, other rumen microbes that can incorporate Se into their cell could provide a better infl ux of Se in the lower gut.…”