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 84.5Dairy 41.3 58.7Sheep and goats 6.2 93.8Swine 95.7 4.3Horses & Mules 27.0 73.0Poultry 100.0 0.0All 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 Alfalfamature
Alfalfa mid-bloom
Alfalfa early bloom
Analysis, DM basis %Crude Protein (CP)TDNDM
12.950
17.058
1860
Value of 100 DM, $CP ValueTDN ValueTotal Value
2.192.804.99
2.893.256.13
3.063.366.42
Total Value/acre $5 tons of Hay8 tons of Hay
449719
552883
578924
Feedlot Performance
Item All Forage Diet All Conc.[] diet
Daily feed intake 23.3 16.0Feed intake % of Body Wt 3.23 2.15Avg. daily gain 2.3 2.8Feed gain ratio 10.06 5.71Average carcass grade Low choice Med. choiceDressing percentage 55.4 59.9Marbling score Abundant AbundantRib eye area (sq. in.) 11.0 10.6Fat over rib (in.) .37 .67Taste panel evaluation 7.6 7.2
Feedlot performance: Hi energy versus all Forage ration
Item Calves Yearling
Hi-Energy All-Forage Hi-Energy All-Forage
LBS. LBS. LBS. LBS.
Avg. initial wt.
488 492 670 672
Avg. final wt. 1042 1053 1165 1147
Avg. daily gain
2.84 2.33 3.07 2.31
Feed
Fats Carbohydrates Proteins
Fatty acids|Glycerol Glucose Amino Acids
Glycolysis
Pyruvate
Acetyl CoA
Kreb Cycle
UreaCycle
Urea excreted in urine Transamination
Electron Transport System
Energy&
Work
CoAATP ADP
2CO2
H+
H2O
Glycogen
Gross Energy
Digestible Energy (DE) (TDN)
Metabolizable Energy (ME)
Net Energy (NE)
Urinary &Combustible Energy
Heat Increment
Net Energy Maintenance (Nem)
Net EnergyProduction (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
Nitrogen freeextract
Crude Fiber
Soluble proteins, lipids, and minerals
Sugars, starches, and pectins
HemicelluloseCellulose
Lignin
SolubleCellcontents
AcidDetergentfiber
Neutraldetergentfiber
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
Pre-bloom
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
Description CP (%)
DM intake (Tons)
Conc. [ ] Purchased
(lbs.)
Purchased Feed Cost
($)Early cut Legume 21 2.17 531 947.40
Legume 18 2.07 733 1176.20Mixed, 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
Effect of Quality of Fescue Hay on Cattle Gains
Composition
Stage of Harvest
Lbs. Harvested 1st cutting
CP (%)
Digestibility ( %)
Intake Per Animal (Lbs.DM)
Lb of Hay/ Lb of Gain
(Lb.)
Gain/Head/Day
(lb.)
Late Boot to Head
1,334 13.8 68 13.0 10.1 1.39
Early bloom 1,388 10.2 66 11.7 13.5 0.97
Early milk 2,823 7.6 56 8.6 22.5 0.42
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 RFVAlf., pre bloom 23 28 38 164
Alf. bud 20 30 40 152Alf. mid bloom 17 35 46 125
Alf. mature 15 41 53 100Brome, late veg. 14 35 63 91
Bermuda, late 8 43 78 66Orchard Grass,early 18 31 55 109
Orchard Grass, early B 15 34 61 95
Wheat Straw 4 54 85 51Source: Holland and Kezar 1990.
Effect of NDF Content of Forage on DMIForage Quality % NDF
(Dry Matter Basis)DMI as Percent of
Body Weight
Excellent 38 3.1640 3.0042 2.8644 2.7346 2.6148 2.5050 2.4052 2.3154 2.22
Source:Van Soest and Mertens.1985.
% Change in Alfalfa Composition at Different Maturities
Harvest Date
Leaf Stem
Cellulose Lignin Cellulose LigninApril 22 7.1 2.43 11.0 1.80April 28 7.0 2.51 10.2 2.10May 5 6.9 2.83 15.2 3.76May 13 7.1 2.37 16.6 4.73May 22 7.1 2.85 22.5 6.77June 4 7.6 2.82 23.5 8.79Source:Burritt et.al. 1984
High Moisture Feeds
• Silage– Corn– Hay
• High Moisture Grains• Green chop• Baglage
Composition of Various Silages
Type of Silage
Analyses on a Dry Matter BasisCrude 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 0.27Forage Sorghum 9.2 57.9 0.30 0.24
Corn Silage – Excellent Energy Source
• 30-35 % Dry Matter• 8-9 % Crude Protein• pH<4.2• Requires 2-3 weeks
for the ensiling process
• Length of cut 3/8 of an inch theoretical cut
• Utilizes entire plant which increases land utilization
• Must be made at proper maturity- Black layer present on kernel
• Proper oxygen free storage essential- hard 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
