Download Animal Science 336

Role of Forage in Nutrition
• Natural feed of all herbivorous animals.
– Provide a source of energy, protein and fiber etc.
• Converts poorly digested feedstuffs to highly
digestible feeds in the human food chain
• Necessary for proper functioning of the digestive
system of all herbivores especially ruminants
– Supplying nutrients for microbial fermentation
– Stimulatory effect
• Muscle tone
– Passage rate
– Maintenance of epithelium
Forage Defined
• Vegetable material in a fresh, dried or ensiled state
which is fed to livestock.
• Average fiber content in dry state = 18%
• Bulky feed with lower energy content
concentrates.
• Forage is used interchangeably with roughage.
• Lower digestibility than concentrates.
• Protein content varies from +20 % to 3 % .
• Forages are generally higher in Calcium and
Potassium but lower in Phosphorus than conc. [ ]
• Higher in fat soluble vitamins than [ ].
% of Feeds for Different Classes of U.S.
Livestock1 (Average)
Class of Animal Concentrates (%) Roughages (%)
Beef
15.5
84.5
Dairy
41.3
58.7
Sheep and goats
6.2
93.8
Swine
95.7
4.3
Horses & Mules
27.0
73.0
Poultry
100.0
0.0
All livestock
38.3
61.7
1USDA
Economic Research Service data for feed years 1983-84.
Forage Types
• Hay
– Alfalfa
– Clover
– Grasses
• Timothy
• Bermuda
• Brome
– Stover
• Corn
• Cottonseed Hulls
• Pasture
–
–
–
–
Permanent
Rotational 200-400# beef/y
Intensive 600# of beef/y
Range
• Silage
– Corn
– Milo
• Haylage
– Alfalfa
– Grass
– Cereal Grains
Hay
• Defined:
– Forage harvested during the growing period and
preserved by drying for subsequent use.
• Magnitude and importance
– 60+ million acres nationwide
– 150 million tons
– $10 billion annual crop
• Economics loss from poor hay making. (Billions)
Hay as an Energy Source
Item
Alfalfa
Alfalfa
Alfalfa
mature
mid-bloom
early bloom
12.9
50
17.0
58
18
60
Value of 100 DM, $
CP Value
TDN Value
Total Value
2.19
2.80
4.99
2.89
3.25
6.13
3.06
3.36
6.42
Total Value/acre $
5 tons of Hay
8 tons of Hay
449
719
552
883
578
924
Analysis, DM basis %
Crude Protein (CP)
TDN
DM
Feedlot Performance
Item
Daily feed intake
Feed intake % of Body Wt
Avg. daily gain
Feed gain ratio
Average carcass grade
Dressing percentage
Marbling score
Rib eye area (sq. in.)
Fat over rib (in.)
Taste panel evaluation
All Forage Diet
All Conc.[] diet
23.3
3.23
2.3
10.06
Low choice
55.4
Abundant
11.0
.37
7.6
16.0
2.15
2.8
5.71
Med. choice
59.9
Abundant
10.6
.67
7.2
Feedlot performance: Hi energy versus
all Forage ration
Item
Calves
Hi-Energy All-Forage
Avg. initial
wt.
Avg. final wt.
Avg. daily
gain
Yearling
Hi-Energy
All-Forage
LBS.
LBS.
LBS.
LBS.
488
492
670
672
1042
1053
1165
1147
2.84
2.33
3.07
2.31
Feed
Fats
Proteins
Carbohydrates
Glycogen
Fatty acids|Glycerol
Amino Acids
Glucose
Urea
Cycle
Glycolysis
Electron
Transport
System
ATP
Pyruvate
ADP
Energy
&
Work
H+
Acetyl CoA
2CO2
H2O
CoA
Kreb
Cycle
Urea
excreted
in urine
Transamination
Gross Energy
Digestible Energy (DE) (TDN)
Urinary &
Combustible
Energy
Metabolizable Energy (ME)
Net Energy (NE)
Heat Increment
Net Energy
Maintenance (Nem)
Net Energy
Production (Nel)
Proximate Analysis
• Moisture
– Dilute nutrient concentration
• Crude Protein
– Quality of Forage
• Crude Fiber
– Structural Carbohydrates, Hemicellulose, cellulose and
lignin
– Negatively correlated to Nutritive value (less digestible)
• Crude Fat
– Fats and lipids in forage 2.25 times higher in energy
than carbohydrates and protein and are highly digestible
• Ash
• Nitrogen-Free Extract
– Calculated
Chemical Analysis – Detergent Analysis
System
• Neutral Detergent Fiber
(NDF)
– The lower the value the
more the animal will eat
– Cell wall material
– Comprised of:
•
•
•
•
•
Hemicellulose
Cellulose
Lignin
Lignified N
Insoluble Ash
• Acid Detergent Fiber
(ADF)
– The lower the value the
more the animal will
eat
– Highly indigestible
plant material in forage
– Comprised of:
• Cellulose
• Lignin
• Insoluble Ash
Proximate Analysis
Van Soest Method
Soluble proteins, lipids, and minerals
Nitrogen free
extract
Sugars, starches, and pectins
Hemicellulose
Cellulose
Crude Fiber
Lignin
Acid
Detergent
fiber
Soluble
Cell
contents
Neutral
detergent
fiber
Effects of Quality of Alfalfa Hay on
performance of Lactating Cows
Stage of
Harvest
Composition
CP
NDF
ADF
DDM
DMI
4%FCM
(%)
(%)
(%)
(%)
(%)BW
Lbs./day
Prebloom
21.1
40.5
30.2
62.7
2.08
87.1
Early
Bloom
18.9
42.0
33.0
61.6
1.97
77.2
Mid
Bloom
14.7
52.5
38.0
54.8
1.48
66.2
Full
Bloom
16.3
59.5
45.9
52.9
1.42
64.7
Effect of 5 Different Qualities of Hay on Daily Feed
Cost 1200 cow herd
Hay Quality
CP
(%)
DM intake
(Tons)
Conc. [ ]
Purchased
(lbs.)
Purchased
Feed Cost
($)
Early cut
Legume
21
2.17
531
947.40
Legume
18
2.07
733
1176.20
Mixed, Mainly
Legume
15.5
1.91
977
1386.80
Mixed, Mainly
Grass
12
1.84
1,158
1608.40
Grass
10
1.77
1,278
1737.80
Description
Effect of Quality of Fescue Hay on Cattle
Gains
Composition
Digestibility
( %)
Intake
Per
Animal
(Lbs.DM)
Lb of
Hay/ Lb
of Gain
(Lb.)
Gain/Head/
Day
(lb.)
13.8
68
13.0
10.1
1.39
1,388
10.2
66
11.7
13.5
0.97
2,823
7.6
56
8.6
22.5
0.42
Stage of
Harvest
Lbs.
Harvested
1st cutting
CP
(%)
Late
Boot to
Head
1,334
Early
bloom
Early
milk
Relative Feed Value (RFV)
• Uses NDF and ADF values to compute an
index to compare all types of forages.
• RFV = % DDM X % DMI / 1.29
• Where
– % DDM = 88.9 – (ADF % X 0.779)
– % DMI = 120 / % NDF
Relative Feed Values of Various Forages
Forage
CP
ADF
NDF
RFV
Alf., pre
bloom
23
28
38
164
Alf. bud
20
30
40
152
Alf. mid
bloom
17
35
46
125
Alf. mature
15
41
53
100
Brome, late
veg.
14
35
63
91
Bermuda, late
8
43
78
66
Orchard
Grass,early
18
31
55
109
Orchard
Grass, early B
15
34
61
95
Wheat Straw
4
54
85
51
Source: Holland and Kezar 1990.
Effect of NDF Content of Forage on DMI
Forage Quality
% NDF
(Dry Matter Basis)
DMI as Percent of
Body Weight
38
40
42
44
3.16
3.00
2.86
2.73
46
48
50
2.61
2.50
2.40
52
54
2.31
2.22
Excellent
Source:Van Soest and Mertens.1985.
% Change in Alfalfa Composition at Different
Maturities
Harvest
Date
April 22
April 28
May 5
May 13
May 22
June 4
Leaf
Cellulose Lignin
7.1
2.43
7.0
2.51
6.9
2.83
7.1
2.37
7.1
2.85
7.6
2.82
Source:Burritt et.al. 1984
Stem
Cellulose Lignin
11.0
1.80
10.2
2.10
15.2
3.76
16.6
4.73
22.5
6.77
23.5
8.79
High Moisture Feeds
• Silage
– Corn
– Hay
• High Moisture Grains
• Green chop
• Baglage
Composition of Various Silages
Type of
Silage
Analyses on a Dry Matter Basis
Crude Protein
(%)
TDN
(%)
Ca
(%)
P
(%)
Corn
8.3
68.0
0.31
0.27
Milo
7.9
55.0
0.34
0.19
Oats
10.0
57.0
0.47
0.33
Alfalfa
17.4
59.0
1.75
0.27
Forage
Sorghum
9.2
57.9
0.30
0.24
Corn Silage – Excellent Energy Source
•
•
•
•
30-35 % Dry Matter
• Utilizes entire plant
which increases land
8-9 % Crude Protein
utilization
pH<4.2
• Must be made at
Requires 2-3 weeks
proper
maturityBlack
for the ensiling
layer present on kernel
process
• Length of cut 3/8 of an • Proper oxygen free
storage
essentialhard
inch theoretical cut
packed.
Corn Silage – cont’d
• Complex sugars and carbohydrates are broken
down into lactic acid, acetic acid, and small
amount of alcohols and other acids
• Small quantities of proteins are broken down into
ammonia, amino acids, amines and amides
• Acidity reaches levels where the ensiling bacteria
die ending the process.
• Molds and yeast growth are inhibited unless air is
re-introduced. (Secondary fermentation)
High Moisture Corn - Barley
• Advantages
–
–
–
–
22-32 % moisture
Reduce drying cost
Harvest earlier
Later maturing –
Higher producing
yields
– Increased feeding
value
• Disadvantage
– Large inventory of
high moisture grain
– Limits market
flexibility
– May freeze or cause fly
problem in warmer
months
– Handling