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 61.71USDA 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)

TDN

DM

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

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

DescriptionCP

(%)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

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 40 152

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 51Source: Holland and Kezar 1990.

Effect of NDF Content of Forage on DMI

Forage Quality % NDF

(Dry Matter Basis)

DMI as Percent of Body Weight

Excellent 38 3.16

40 3.00

42 2.86

44 2.73

46 2.61

48 2.50

50 2.40

52 2.31

54 2.22Source:Van Soest and Mertens.1985.

% Change in Alfalfa Composition at Different Maturities

Harvest Date

Leaf Stem

Cellulose Lignin Cellulose Lignin

April 22 7.1 2.43 11.0 1.80

April 28 7.0 2.51 10.2 2.10

May 5 6.9 2.83 15.2 3.76

May 13 7.1 2.37 16.6 4.73

May 22 7.1 2.85 22.5 6.77

June 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 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• 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