Effects of selenium yeast on rumen fermentation, lactation performance and

feed digestibilities in lactating dairy cows

C. Wang A, Q. Liu A, , W.Z. Yang A,B, Q. ⁎Dong A, X.M. Yang C, D.C. He C, P. Zhang D, (July 2009)Presented by AbouBaker Elhajee

Introduction

• Selenium is recognized as an essential trace element.

• It is a powerful catalytic element constitutingthe active centre of about 20 selenoproteins • Selenium displays metabolic function related

to maintenance of integrity and defenses of the organism.

Supplementation

• Se content within plants can be extremely variable. Consequently, selenium in diets can be deficient.

• Se supplementation may be required to improve the performance and health of dairy , enhance the nutritional quality of the milk product

Forms

• Inorganic Se (i.e., sodium selenite or selenate) and organic Se (i.e., selenium-yeast [SY]).

• Most studies reported that organic Se is less toxic than inorganic Se, Bioavailability of SY higher than inorganic Se sources , leads to higher Se content in milk.

• Results of SY on milk yields and milk components from literature are inconclusive.

• These contrasting results could be due to differences in the composition of the diet and/or to the dose of SY and lactation period of dairy cow (Juniper et al., 2006)..

Objectives

• The aim of this work was to evaluate the effects of SY supplemented dose on rumen fermentation, lactation performance, milk selenium content and feed digestion in mid-lactation dairy cows.

Materials and methods

• Animals and experimental design. - Twenty-eight Holstein dairy cows were

assigned to a replicated 4×4 Latin square. - Treatments were: control, LSY, MSY and HSY

with 0,150, 300, and 450 mg SY per kg of (DM) respectively.

- Experimental periods were 45 days with 30 days of adaptation and 15 days of sampling.

• Dry matter intake, milk yield, milk components and milk selenium.

- Feed offered and refused were measured daily for each cow (DM intake).

- Milk yields were recorded daily. - Milk Samples for analysis of milkcomposition

and measure milk Se concentration.

• Rumen pH and fermentation characteristics. - were measured on two consecutive days at

the beginning (days 1 and 2) and end (days 44 and 45) of each period. At 0, 3, 6, and 9 h after the morning feeding, samples (about 100 mL) of rumen fluid were obtained anaerobically via the esophagus using a stomach tube

- Ruminal pH was immediately measured using an electric pH meter

• Rumen pH and fermentation characteristics. -Samples were then strained through four

layers of cheesecloth. Five milliliters of filtrate was preserved by adding 1 mL of 250 g/L (w/v) meta-phosphoric acid to determine acetate, propionate and butyrate, and 5 mL of filtrate was preserved by adding 1 mL of 20 g/L (w/v) H2SO4 to determine NH3.

• Apparent digestibility in the total tract -Cows were dosed via the esophagus with 5 g of

chromic oxide per day per cow in two equal proportions at 07:00 and 19:00 h from days 23 to 43 of each period as a digestion marker..

• -fecal samples were collected from the rectum of each cow during days 31 to 43 of each period .

Results

• Ruminal pH and fermentation. -There was no significant difference in ruminal

pH . -Ratio of acetate to propionate was lower for

LSY, MSY and HSY than for control

• Dry matter intake, milk yield, milk components and milk selenium

-Dry matter intake was not affected. -Milk yields were higher for LSY and MSY than

for HSY and control• -Milk selenium content was linearly and

quadratically increased as increasing SY supplementation.

• Digestibility in the total tract. Were higher for LSY and MSY than for control

and HSY.

Conclusion

• Increasing supplementation of cow diet with selenium yeast from 150 to 300 mg/kg dietary DM compared with control increased milk yield and 4% FCM.

• Improved milk production was likely due to the increased total digestibilities of feeds since DMI was not affected.

• The further increase of SY dose from 300 to 450 mg/kg dietary DM was not beneficial

Recommendation

• Selenium yeast modulates the digestive microorganisms or enzymes in a dose-dependent manner and the optimum SY supplemented dose was about 300 mg/kg in the present experimental conditions.

• SY supplementation in the diets of lactating dairy cows could be an efficient way to increase milk Se content.

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