6. Forage

Question 1

Grass varieties

Answer 1

-perennial ryegrass
-italian ryegrass
-cocksfoot, meadow fescue, brome grass, timothy, bent grass, meadowgrasses
-clover

Question 2

Grassland reseeding

Answer 2

-perennial ryegrass 70%
-italian ryegrass 19%
-cocksfoot 4%
-timothy 7%

Question 3

Differences between new and old pasture

Answer 3

old pastures have lower yield and digestibility

Question 4

Aim of grassland management

Answer 4

-provide supply of high quality herbage over the growing season
-avoid waste
-avoid inefficient utilisation by animal
-provide feeding for winter

Question 5

Grazing behaviour

Answer 5

cattle graze 6-11 hours per day
intense periods after dawn and before dusk
animals move while grazing -slowly in uniform crop and faster in variable crop
grazing followed by rest and rumination
can walk 2-6km/day grazing
drink 2-4 times a day
milking enter/exit field 4 times a day

Question 6

Factors affecting intake of herbage

Answer 6

Animal factors:
-metabolic weight,
-production,
-stage of lactation
Sward factors
-herbage quantity
-herbage quality
Effort of grazing
-difficult conditions

Question 7

Effect of animal on pasture

Answer 7

Botanical changes
-frequent grazing, ryegrass
-lax grazing, cocksfoot
-severe grazing, meadowgrasses
Treading and poaching
-compaction more severe when soil wet
-depends on stocking rate, rainfall
Dung and urine
-faeces production
-sheep faeces more evenly distributed
-urine, plant nutrients readily available
Application of slurry
-allow 5 weeks from application to grazing
-contains NPK
Full return of faeces and urine increases herbage yield by 20-40%

Question 8

Grazing Practices

Answer 8

Continuous stocking
-access to one area for entire grazing season
-balance number of stock with production
Intensive continuous stocking
-reduce number as grass supply drops
Rotational grazing
-divide into number of similar sized paddocks, stock moved in sequence around
Strip grazing
-move electric fence everyday or every 12 hours
-rotation cycle is 15-21-30 days
Leader-follower rotational grazing
-two groups, one follows other
-better use of grass, less waste
Integrated grazing and conservation
-subdivide pasture into 2 sections in ratio of 60:40
-early season graze 40 conserve 60
-mid graze 60 conserve 40
-end season graze 100
Alternate cutting and grazing
-graze part cut early season in mid season and vice-versa
-improves grass quality
-can have shortage of grass for a few weeks
Zero grazing
-harvest all grass and feed as silage

Question 9

Animal problems at pasture

Answer 9

bloat
parasites
mineral deficiency/toxicity

Question 10

Bloat

Answer 10

-common with diets high in legumes, lucerne, clover
-problem with lush grass
-control: anti-foam in water, provide some fibrous feed, feed small quantities of pasture with high clover

Question 11

Haymaking

Answer 11

Reduce moisture content of forage to 20% or less
-suppress fungal growth
-suppress thermophilic bacteria
-suppress moulds
Weather most important
-drying conditions and low humidity
Rapid drying required - mature crop
Harvest 1 June to August
Mature herbage dries easier and quicker, but quality of hay poorer

Question 12

Forage

Answer 12

mainly grasses, for both domestic and wild animals

Question 13

Effect of rain on hay quality

Answer 13

Increases moisture content
-prolongs enzyme actions
-increases tossing required
-increases leaching
Encourages mould growth

Question 14

Nutrient losses during haymaking

Answer 14

Plant enzymes
-respiration CHO to CO2 and H2O
-proteolysis, proteins to amino acids
Oxidation
-carotene destroyed
Mechanical damage
-leaf loss as leaf dries faster than stem
Leaching
-loss of soluble sugars
-loss of amino acids and other soluble nitrogenous constituents
-most caused by rain while saving hay

Question 15

Silage

Answer 15

controlled fermentation of crop at high moisture content
fermentation produces organic acids from bacterial action on sugars
quantity of acid produced proportional to
-amount of sugar
-type of bacteria
-type of crop
-moisture content
two fermentation types
-aerobic
-anaerobic

Question 16

Aerobic Fermentation

Answer 16

air trapped in crop when ensiled
respiration proceeds until oxygen depleted
CHO + O2 = CO2 + Heat
loss of carbohydrate
limited loss unavoidable
If extra air enters the silage
-sugar loss by respiration
-increased temperature
-if greater than 40C increased protein denaturation
Decreased digestibility and feed value of silage

Question 17

Anaerobic fermentation

Answer 17

in absence of air anaerobic microbes produce acid and preserve the crop
Type and quantity of acid critical
-lactic acid desirable
-insufficient acid, clostridia produce butyric acid - protein breakdown, poor fermentation

Question 18

Relationship between acid type and silage quality

Answer 18

when lactic acid high, butyric acid ammonia nitrogen and pH is low

Question 19

Moisture content of silage

Answer 19

Low DM herbage (<18%)
–needs high level of acidity to check clostridial growth
Dryer herbage (25-28% DM)
–pH 4.4 adequate
High DM herbage
–initial fermentation to pH 4.8 adequate but fermentation limited
–free sugars remain
–growth of M/O on opening pit
–aerobic deterioration

Question 20

Soluble carbohydrate content of silage

Answer 20

Depends on
–grass species
–weather
–nitrogen fertilizer
–time of N application
Herbage sugar level of 3% in fresh grass necessary to ensure successful preservation of silage
–wilting
–silage additives

Question 21

Wilting to improve preservation

Answer 21

Decreases effluent
Increases dry matter
–increases relative sugar content
–less water to transport
–higher field losses
26% DM normally results in good preservation
Dry windy weather, 1% increase in DM/hr
Typical dull weather, 0.4% increase in DM/hr

Question 22

Additives to improve preservation

Answer 22

Affect sugar content or pH directly
May protect proteins
May improve animal performance
use in difficult crop and difficult conditions
–grass variety –dull wet weather
–young leafy –late regrowth
–well fertilised –soil contamination
–low sugar

Question 23

Value of silage as a feed

Answer 23

quality, energy and protein content
amount animal east, taste small etc.

Question 24

On-farm assessment of silage quality

Answer 24

variable layers in pit?
DM content, squeeze in hand
-juice in stream, DM less than 20%
-juice drops only, DM 25 -26%
-wetness on palm, DM 26-30%
ME value, leafiness, coarseness of stem
Type of fermentation
-well fermented, yellow green and fruity smell
-butyric silage, green brown dull and unpleasant smell
-overheated silage, brown black, small of caramel, charred
pH, check with lithmus paper

Question 25

Moulds

Answer 25

Aspergillus sp. linked to abortion in cattle and sheep
linked to COPD horses from mouldy hay

Question 26

Listeriosis

Answer 26

Disease of cattle and sheep sometimes linked to feeding incompletely sealed big bale silage
Listeria monocytogenes soil borne, associated with aerobic deterioration
Stemmy silage, iritis

Question 27

Botulism

Answer 27

Contamination by dead carcasses, soil, manure
Clostridium botulinum may multiply in silage

Question 28

High ammonia levels

Answer 28

associated with lameness and scour in dairy cows
inverse relationship between dry matter content of silage and lameness