Lecture 3: Making of silage, hay and haylage

Question 1

Basics of making silage/haylage

Answer 1

• Cut when yield is between 2500 - 4000 kg DM per hectare
• Prewilting period after cutting (1-2 days) till DM content is 30-50% or even up to 75% (haylage for horses)
• Preservation is based on fermentation of sugars: lactic acid formation by bacteria
• Additives might be used: molasses, organic acids, salts, bacteria etc

Question 2

What determines the fermentation process of grass?

Answer 2

• Chemical composition (DM, sugar, protein, nitrate)
• Temperature
• Chopping

Question 3

What are silage quality indicators?

Answer 3

Smell
Colour
Chemical analysis
– Ammonia-N
– pH in relation to DM%
– Spores: Clostridia
– Energy content

Question 4

What are the results of conservation?

Answer 4

• pH-drop
• Lactic acid
• Acetate
• Propionate
• Butyrate
• NH3
• Other fermentation
products.

Question 5

What are the four phases of conservation?

Answer 5

• Aerobic phase
• Fermentation phase
• Stabile phase
• Feeding / opening

Question 6

Describe the aerobic phase of conservation?

Answer 6

Negative effects of oxygen silage pit:
– Poor growing of lactic acid
bacteria (wanted bacteria!)
– Good growth circumstances for
fungi and yeasts
During harvesting; get the oxygen out:
– Making it dense

Question 7

Describe the fermentation phase of conservation?

Answer 7

• due to ensiling, lactic acid bacteria make lactic acid from sugar
  Factors:
• competition between microflora
• Feed
• Low oxygen
  The presence of lactic acid results in a quick pH drop

Question 8

What is the difference between lactic acid bacteria (homo or hetero fermentative)

Answer 8

Homo fermentative:
• quick
• Stopped by lactic acid
• Limited loss of dry matter
Hetero fermentative:
• Slow
• Also at low Ph
• more loss of dry matter

Question 9

What is the effect of protein?

Answer 9

• pH buffer capacity
• May lead to poor conservation
• A high use of WSC can make it stable again

Question 10

Relation between dry matter and needed pH for a stabile product?

Answer 10

Low dry matter; lower pH for a stable product
Low dry matter; more WSC needed to reach the
low pH!

Question 11

What are undesired organisms in the conservation process?

Answer 11

• Entero bacteria
– Ferment carbohydrates; but no lactic acid
– At early fermentation
• Obligate anaerobes like Clostridium species
– WSC and lactic acid to butyric acid
• Clostridium bacteria very unwanted in dairy (milk quality!)
• Listeria monocytes
– Pathogen proliferates at air ingress, especially in big bales
• Yeasts
– Develop easy at silo opening
– Cause heating and aerobic deterioration

Question 12

How to reduce clostridial activity?

Answer 12

• Reduce moist
– Pre wilting (dry)
• Enough WSC
– If not, add molasses
• Adding inoculants of lactic acid bacteria
• Add acids
– Start with lower pH, less WSC needed
• Avoid contamination with soil or manure (the source of
clostridium!)

Question 13

What is aerobic deterioration?

Answer 13

• Oxygen enters the stored product
• Aerobic microbes become active: deterioration
• pH rises
• Other microbes become active
• Loss of feeding value

Question 14

pH and temperature relation in silage clamp

Answer 14

If the temperature rises in the silage clamp, so does the pH

Question 15

Prevent aerobic deterioration by:

Answer 15

– Sand or weight
– Cutting area smooth
– High speed of feeding
– Susceptible pits, feed in winter

Question 16

Conservation process of hay

Answer 16

• Predominantly made during summer
• Cut when yield is between 4000 and 5000 kg DM/ha
• Wilting period of several days
• DM% should reach app. 85%
• Hay should be stored dry to avoid moulds to develop
• Enzymatic degradation of plant material stops at around 85%dm