Why trial BSY?

BSY is a wet co-product from the brewing process. While it can be dried, BSY is most often integrated into liquid feeds for pigs. Unfortunately, drying the yeast is not always feasible and pig systems that feed liquid rations are declining, so many breweries discard spent yeast as waste.

Although choosing BSY for cattle is uncommon, some European dairy farms have adopted it and report positive results. It is claimed that feeding yeast, particularly during times of heat stress, supports DMI and boosts yield. To test these claims, we implemented a Duynie field trial to see how high-yielding dairy cows performed on a ration including BSY.

The aims of the trial

In setting out on the trial, we had three primary objectives:

  • Evaluate dairy cow performance on a total mixed ration including liquid BSY
  • Determine the impact on milk quality of the ethanol in BSY
  • Establish the maximum safe level of liquid BSY (and therefore ethanol) in a high-yielding dairy cow’s ration.

Benefits

From available research into the use of BSY and ethanol as cattle feed we discovered the following benefits and considerations:

  • The product contains a high level of metabolisable lysine (which supports milk production) and its high soluble protein contributes to rumen degradable protein.
  • An ethanol content of 40 to 50g/kg is partly fermented to acetic acid and partly absorbed into the blood stream where it contributes to energy requirements.
  • Ethanol is a high energy source comparable with propylene glycol and feeding it results in higher yields and boosts milk-fat levels.
  • As ethanol is a naturally occurring intermediate and end-product of rumen fermentation, at common feeding levels there should be no interference with rumen fermentation and no adverse effects on rumen efficiency and health.
  • Yeast cell wall fragments potentially deliver the same prebiotic benefits as the dry yeast cultures commonly used as feed.
  • The product is highly palatable with a pleasant aroma and can be used to encourage feed intakes.
  • Liquid BSY can replace water in achieving desirable ration dry matters. Due to its low pH it contributes to heat inhibition of TMR.

Considerations

  • The composition of the product can be variable and proper deactivation at the brewery is needed.
  • Ethanol evaporation from the ration is possible, although it is indicated to be low
  • BSY is an unbalanced product with high calculated rumen degradable protein balance
  • According to some dated research, ethanol may have a negative effect on milk flavour. More modern research in a TMR setting suggests otherwise.

Typical Nutritional values

DM

13.5 % DM

NCGD

94 % DM

CP

35 % DM

Starch

10 % DM

CF

0.7 % DM

Sugar

6 % DM

ASH

5.5 % DM

pH

4.4

Oil B

1 % DM

ethanol

342 g/Kg DM

NDF

3 % DM

ME

13.0 MJ/Kg DM

Effects

Milk quality and flavour are unaffected by ethanol feeding via TMR.

Milk quality and flavour are unaffected by ethanol feeding via TMR.

Variability of BSY has no significant impact on dairy cow performance.

Variability of BSY has no significant impact on dairy cow performance.

Ethanol evaporation from the ration at an approximate rate of 4% per hour.

Ethanol evaporation from the ration at an approximate rate of 4% per hour.