LECTURE 20
FEEDLOT CATTLE NUTRITION
pp. 409-418
GOALS WHEN FEEDING
FINISHING CATTLE
• Maintain animal health
• Produce a desirable carcass
– Choice grade (5.0 to 8.5% intramuscular fat, 28% body
fat)
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–
–
–
• Body weight will vary with genetics, growth rate, and
implants
Yield grade 3 or less
Acceptable maturity (< 30 months)
White fat and bright red muscle
Carcass weight between 600 and 900 lbs
• Minimize production costs
– Feed
– Non-feed costs (Facility depreciation, Interest etc)
• Minimize environmental impacts
– Maximize feed efficiency
TRADITIONAL SYSTEM OF FEEDLOT FINISHING OF
BEEF CATTLE
Feeder calf or yearling
(600-900 lb)
Implanted with estrogen w/ or
w/o Trenbolone acetate
Feed high grain diet (80-90% grain)
with ionophore
Gain 3-4 lb/day
Feed/gain 6-7
Harvested at 1200 –1400 lb
producing a carcass with a
choice quality grade and a
yield grade of 2 or 3
Season prices:
High in March and April
Low in July
FEED INTAKE OF FEEDLOT CATTLE
• Normal intake is 2 to 3% of body weight
• Factors
– Degree of finish as affected by body weight, cattle type,
implants etc.
– Feeding after a period of restricted gain (backgrounding or
grazing)
• Part of compensatory gain
– Diet
• Ionophores
• Forage concentration
• Fat concentration
• Nutritional imbalance
– Potassium deficiency
– Environmental
• Temperature (base is 15 to 25 C)
– Decreases by 10 to 35% if temperature increases to 35C
– Increases by 16% is temperature decreases to -5 to -15C
• Mud
– Decreases by 15% if mud depth is 4 to 8 inches
EFFECT OF BODY WEIGHT AND
FATNESS ON FEED INTAKE
Body fat
DMI
• Maintenance energy requirement of finishing
beef cattle
– NEm, Mcal/day = .077BW.75
– Modified by a large number of factors
– Maintenance Modifiers
Modifier
Modification
Change in NEm reqt.
Breed
Beef breed
Base
Dairy breed
Increase by 20%
Brahman breed
Decrease by 10%
Sex
Bull
Increase by 15%
Previous
nutrition
BCS<5
Decrease by 5%/BCS unit
( Another part of
compensatory gain)
BCS>5
Increase by 5%/BCS unit
Environmental
stress
Cold temp, dry coat, BCS
5
Increase by 15%
(Include temp,
wind, BCS, hide
& coat thickness,
coat cover and
heat increment)
Cold temp, dry coat, BCS
4
Increase by 20%
Cold temp, snowy coat,
BCS 5
Increase by 96%
Heat stress
Increase by 11 to 25%
EFFECTS OF BODYWEIGHT ON THE NEm and NEg
REQUIREMENT TO GAIN 3.5 lb/day FOR STEERS AT
EITHER AT FINISHED WEIGHT OF 1200 OR 1400 LB
ENERGY SOURCES FOR FEEDLOT DIETS
• Grains
– Fed at levels up to 95% of the diet
– Usually are processed
• Grinding, cracking or rolling
• High moisture corn
• Steam-flaking
– Cattle must be properly adapted to diet
– Limits
Grain
Maximum fed, % of DM
Consideration
Corn grain
92
Milo
92
Wheat
50
Highly fermentable
starch
Oats
25
High fiber, low energy
Ground ear
corn
95
(If no forage fed)
High fiber
• Grain processing byproducts
Grain byproduct
Maximum fed, % of DM
Consideration
Distillers dried grains
w/ solubles (DDGS)
40
High sulfur,
High fat
Corn gluten feed
20-30
High fiber
Distillers solubles
20
(If DDGS not in diet)
High sulfur, high
fat
Soy hulls
25
High fiber
• Fat supplements (Tallow, Vegetable-Animal Fat)
– Increase energy concentration
– Reduce dustiness
– Limit to 5% of DM
• Molasses
–
–
–
–
–
Increase energy concentration
Reduce dustiness
Increase palatability
Increase binding of pellets
Limit to 5% of DM
ADAPTATION TO HIGH GRAIN DIETS
• Rumen microbial population must be slowly adapted
to high grain diets to prevent:
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–
–
–
Lactic acidosis
Founder
Polioencephalomalacia
Bloat
• Systems
– Hand feeding
•
•
•
•
•
•
Cattle fed forage for 4 to 7 days
Start feeding grain at 0.5% BW
Amount of grain increased at 1 lb/day to 1% of BW
Amount of grain increased at 1/2 lb/day to full feed
Decrease forage as grain increased
Feed bunks must be monitored to ensure feed
consumption
– If intake decreases or ceases, slow rate of increase
– Self-feeding a mixed ration
Days
Roughage:Concentrate
1-4
100% hay
5-8
50:50
9-13
40:60
14-17
30:70
18-21
20:80
22-25
15:85
26
10:90
– Supplementing Vitamin A at 30,000 to 50,000 IU/hd/day and
Vitamin E at 400 to 800 IU/hd/day can assist in managing
stress
MEETING THE FIBER REQUIREMENTS OF
FEEDLOT CATTLE
• Need for fiber in ruminant diets
– Stimulate rumination and saliva secretion
– Prevents
•
•
•
•
Parakeratosis of rumen wall
Liver absess
Acidosis
Bloat
• Requirement is for effective NDF (eNDF)
– Includes fiber content and physical form of fiber
• Requirements
– 8% eNDF if:
• Good bunk management, ionophore fed
– 20% eNDF if:
• Variable bunk management, no ionophore
• eNDF concentrations of common feeds in
feedlot diets
– Feed
eNDF, % of DM
Ground corn stalks
65
Ground hay
51
Corn silage
33
Soy hulls
22
Corn gluten feed
13
Whole corn grain
10
Cracked corn
8
Ground corn
5
Distillers dried grains w/solubles 4
Soybean meal
3
• Metabolizable protein supply dependent on:
– Ruminally undegraded protein
– Microbial protein synthesis
FACTORS AFFECTING THE PROTEIN
REQUIREMENTS OF GROWING BEEF
CATTLE
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•
•
•
Animal age and weight
Compensatory gain
Use of hormone implants
Feed intake
PRACTICAL IMPLICATIONS OF MP REQTS. OF
FINISHING BEEF CATTLE
• Cattle at light weights relative to finishing weight will
benefit from sources of rumen undegradable protein
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–
–
–
Distillers grains w/solubles
Corn gluten meal
Expeller processed soybean meal
Blood meal
• Cattle at moderate weights only need to be
supplemented with rumen degradable protein
sources
– NPN
• Recall rules for safe use of NPN
• Cattle near finishing weights obtain adequate
metabolizable protein from a corn-corn silage diet
with no protein supplementation
• If DDGS are fed at 20 to 40% of the DM at any time
during feeding, no protein supplementation is
necessary
MINERAL NUTRITION OF FEEDLOT CATTLE
• Salt (NaCl)
– Should be supplied at 0.25% of diet DM
• Calcium and phosphorus
– Feeds commonly used for feedlot diets contain low
amounts of CA and adequate to high amounts of P
Ca, % of DM
P, % of DM
Reqt
0.4 – 0.6
0.24 – 0.30
Corn grain
0.03
0.32
Corn silage
0.25
0.22
DDGS
0.26
1.0
– Add limestone to maintain Ca:P ratio of 2:1
• Prevents urinary calculi
• Potassium
– Borderline on high grain and corn silage diets
– Monitor and supplement if:
• Low feed intake
• Heat stress
• Sulfur
– Toxic is fed at greater than 0.4% of diet
• Causes polioencephalomalacia
• Occurs at lower dietary levels of S if S content of water is
high
– May be a problem in diets containing high levels of Distillers
dried grain w/ solubles
• DDGS contain as much as 1.0% S
– Management
• Do not feed > 40% DDGS in cattle diets
• Increase forage content of diet (15%)
• Delay addition of high levels of DDGS until cattle
adapted to grain
• Use DDGS from plants that contain consistent levels of S
• Supplement cattle fed DDGS with 150 – 200 mg
thiamine/day
• Trace minerals
– Cu, Zn, Fe, Mn, Co, and I should be supplemented in a
premix
VITAMIN NUTRITION OF FEEDLOT CATTLE
• Vitamin A
– Supplement at 30,000 – 50,000 IU/d during adjustment
– Supplement at 20,000 – 30,000 IU/d after adjustment
• Vitamin E
– Supplement at 400 – 800 IU/d for first 30 days in feedlot
– Supplement at 500 IU/d during last 100 days in feedlot will
improve product shelf life
• Vitamin D
– No need for supplementation if exposed to sunlight
• B vitamins
– Thiamine supplementation at 150 – 200 mg/d may reduce
the risk of polioencephalomalacia in cattle fed DDGS
– Other B vitamins not needed
FEED ADDITIVES AND IMPLANTS FOR
FEEDLOT CATTLE
Feed
additives
Implants
Class
Products
Effects
Ionophores
Monensin,
Lasalocid,
Salinomycin
Increase propionic acid and
decrease methane production in
rumen, decrease feed intake,
increase feed efficiency, increase
ADG in cattle on high forage
diets
Progestogen
Melengesterol
acetate (MGA)
Prevents estrus in heifers,
increase ADG and feed
efficiency
B-agonist
Ractopamine
(Optiflex),
Zilpaterol
(Zilmax)
Fed during last 28 – 42 days
in feedlot. Increases ADG,
feed efficiency, ribeye size
and retail meat yield
Estrogen
Estradiol
Progestogen
Progesterone
Increase rate of gain, feed
efficiency, and protein gain
Androgens
Trenbolone
acetate