Lecture 24
Beef Cow Nutrition
Reading: pp 373-381
GOALS OF FEEDING BEEF BREEDING
HERDS
• Optimize cow reproduction
– 1 calf every 365 days
• Optimize calf production
– Acceptable weaning weight
– Acceptable quality
• Minimize feed costs
– Minimize stored feeds fed
• Maintain forage and natural resources
TRADITIONAL BEEF COW MANAGEMENT IN MIDWEST
Cows
Calves
Months
Management
Nutrition
Management
Nutrition
Feb–
Apr
Cows calve
Fed stored feeds (Hay &
supplements)
Mineral/vitamin
supplement free-choice
Born
Suckle cows
AprOct
Cows bred in
late May –
July
Graze pasture
Mineral supplement freechoice
Mg in mineral in Apr-May
& Sept-Oct
Calves at cow
side
Suckle cows
May be
creep fed in
Aug-Oct
OctDec
Late lactation
& midgestation
Graze corn stalks with
protein supplement.
Mineral/vitamin
supplement free-choice
Calves weaned
Placed in
feedlot or in a
backgrounding
program
Started on
high grain or
left on mixed
forage/grain
diet
DecFeb
Late
gestation
Fed stored feeds (Hay &
supplements)
Mineral/vitamin
supplement free-choice
USE OF CONDITION SCORING TO MAINTAIN
REPRODUCTION IN BEEF COWS
• Condition scores for beef cows Empty body fat, %
– Condition score 1 – Emaciated
0
– Condition score 2 – Very thin
4
– Condition score 3 – Thin
8
– Condition score 4 – Borderline
12
– Condition score 5 – Moderate
16
– Condition score 6 – Good
20
– Condition score 7 – Very good
24
– Condition score 8 – Fat
28
– Condition score 9 – Very fat
32
BODY CONDITION SCORE GOALS FOR
FEEDING BEEF COWS
• Desired body condition scores
Production stage
Desired body condition
score (9-point scale)
Initiation of breeding
season
5
Calving
5
If extra energy not
offered post-calving
4
If energy supplied prebreeding is 30% greater
than requirements
• Never have cows at BCS < 4 or > 6
• Breeding problems
• Calving difficulties
• Expense
Comment
FEED INTAKE OF BEEF COWS
• Normal amounts of feed consumption
Daily DMI, % body wt
– Dry, pregnant cows
– Lactating cows
2.0
2.5 – 3.0
• Factors reducing feed intake
– High levels of NDF
– High energy concentration
– Short sward height
• At less than 8 inches
• At less than 1 ton/ac
36
1200 lb cow w/20 lb
peak milk
DMI, lb/day
34
1400 lb cow w/30 lb
peak milk
32
30
28
26
24
22
20
1
2
3
4
5
6
7
8
9
Month post-calving
10 11 12
ENERGY REQUIREMENTS FOR BEEF
COWS
• Maintenance
– 70% of the requirement
– Needed for basal metabolism, activity, and body
temperature regulation
• Pregnancy
• Growth
• Lactation
• Maintenance energy requirement of beef cows
– 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%
Lactation
Lactating
Increase by 20%
Previous
nutrition
BCS<5
Decrease by 5%/BCS unit
BCS>5
Increase by 5%/BCS unit
Grazing
Hill, poor pasture yield
and digestibility
Increase by 30%
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%
Energy Requirements for Pregnancy and Lactation
• Pregnancy
– Increases energy requirement during last trimester by 80%
• Lactation
– Energy requirement affected by daily milk production
• Peak requirement occurs at approximately 8 weeks post-calving
Increase in NEm reqt, Mcal/d (%)
Peak milk, lb/d
8 wk post-calving
25 wk post-calving
20
6.7 (72%)
2.5 (27%)
30
10.1 (108%)
3.8 (40%)
• NE requirements for pregnancy and lactation are added
to NEm requirement
– Variation in requirement associated with these processes after
the seasonal energy requirements of beef cows
Daily NEm REQT OF BEEF COWS IN RELATION
TO PHYSIOLOGICAL STATE
REQUIRED NEm CONCENTRATION OF DIET
FOR BEEF COW IN RELATION TO CALVING
COMPARISON OF THE NEm REQT OF BEEF
COWS TO THE NEm CONCENTRATION OF
SOME COMMON FEEDS
SEASONAL ENERGY REQUIREMENTS
WILL VARY WITH CALVING DATE
NE reqt., Mcal/day
25
February calving
April calving
August calving
20
15
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Months
MATCHING COW ENERGY REQUIREMENTS
WITH FORAGE SUPPLIES FOR GRAZING
• Management implications of variations in energy
requirements of beef cows
– Use of large, dairy breeds for beef production should
be restricted to operations with ample forage supplies.
• Match cow type to nutritional environment
– Match calving season with availability of forages for
grazing
– Energy requirements in late winter increase because of
cold stress, pregnancy and early lactation
• Save best forage late winter
– Early weaning may be used to reduce cow energy
requirements if feed resources are limiting.
• Will improve rebreeding efficiency
– Corn silage and other high quality stored forages
should be limit-fed if used for beef cows
– Allowing cow body condition to decrease to 4 early in
gestation will decrease energy needs late in gestation.
– Maintaining good pasture yield and quality will reduce
energy requirements while increasing forage energy
concentration
• Risk management for energy deficiency
(Quantity or Concentration)
– Supplement cows with feedstuff with higher
energy concentration to obtain a BCS of 5
• Higher quality forage
• Grain
• Grain byproducts
• Do not rely on protein blocks for energy source
– Wean calves to reduce energy requirement
– Creep feed calves
CREEP FEEDING OF CALVES
• Feeding a supplement that is high in energy and
protein in a feeder that only calves can access
• Common composition
– Grain (Corn, oats etc)
– Grain by-products (DDGS, corn gluten feed etc)
– Protein supplements (Soybean meal, corn gluten meal etc)
• No NPN
– Mineral and fat-soluble vitamin supplements
• Desire consumption of 3 to 4 lb/day
– May be controlled by salt concentration
• Advantages
–
–
–
–
Increased weaning weights
Feeder calves adapted to grain
Increase carrying capacity of pastures
Maintain cow reproduction if forage is limiting
–
–
–
–
Feed cost
Inefficient weight gains (10 lb grain/1 lb BW gain)
Reduced market price of feeder calves/lb
Excessively fat replacement heifers
• Limitations
PROTEIN REQT OF BEEF COWS
• Protein requirement of ruminants is for
metabolizable protein
• Metabolizable protein supply dependent on:
– Ruminally undegraded protein
– Microbial protein synthesis
• Microbial protein synthesis is adequate to meet
the metabolizable protein requirement of mature
beef cows
• Implications
– The protein requirement of mature beef cows is a
requirement for ruminal degradable protein
• Rumen undegradable protein needed for replacement
heifers
– The protein requirement of beef cows can be
expressed as crude protein
– The protein requirement of beef cows can be met by:
• True protein sources
– Generally from plant sources
• NPN sources (usually urea)
– Should not supply greater than 1/3 of the crude protein
in diet
– Should not comprise greater than 1% of the diet DM
– Should be supplied with an energy source (grain, grain
byproducts, molasses)
CRUDE PROTEIN REQUIREMENT OF BEEF
COWS IN RELATION TO CALVING
COMPARISON OF CP REQT OF BEEF COWS AND CP
CONCENTRATION OF COMMON FORAGES
• Implications
– Protein supplementation not needed for beef
cows grazing or fed:
• Well-managed cool season grass and grass-legume
pastures
• Medium to high quality cool season grass and grasslegume hay
– Protein supplementation needed for beef cows
grazing or fed:
• Mature warm season grasses
• Corn stalks
• Mature cool season grass hay
• Protein supplementation systems
– Hand-feeding
• 1 ½ to 2 lb of a supplement containing 40 – 44% protein
• Requires feeder to prevent waste
– Can feed supplement as cubes on ground
• Can be offered every 2 or 3 days
– Liquid supplements
• Mixtures of molasses, NPN source (urea), true protein
source (whey, corn steep water), phosphoric acid, soluble
forms of trace minerals and vitamins A, D, and E, and
possibly fat and propylene glycol
• Contain 24 to 40% CP
– As much as 100% from NPN
• Fed free choice in a lick wheel feeder tank (150 – 250 gal)
– 25 cows/wheel
• Desire 1 to 5 lb of consumption/day
– Observe consumption
• Do not use if forage quantity is inadequate
• Keep feeder full
• Protein block or tubs
– Mixtures of true protein sources (Soybean meal, cottonseed
meal, DDGS), molasses, urea, calcium and phosphorus
sources, salt, trace mineral and vitamin A and D
supplements, and binder (lignin sulfonate, cement)
– Blocks may be 50 to 500 lb
– Supply 1 block/10 to 20 cows
– Contain 15 to 40% CP
• 0 to 50% from NPN (urea)
– Desire 1 to 2 lb consumption
• Controlled by hardness, salt content, or positioning of
block
• May be difficult for old cows
– Do not feed if forage quantity is inadequate
– Weather losses may occur
– Avoid sheep from consuming block
• Total mixed ration
–
–
–
–
Protein supplement mixed into ground forage
Ensures diet is balanced
Minimizes waste
Requires grinding, mixing, daily feeding, and feed bunk
MINERAL SUPPLEMENTATION OF BEEF
COWS
• Traditional system
– Free choice feed a 1:1 mixture of dicalcium
phosphate (or bone meal) and trace mineral salt
• Problem
– Forages contain adequate P if forage is immature
and grown on soil with adequate P
– Expensive
– Environmental load
• Recommended system
– Test forage for P and supplement P ONLY if forage
is mature, weathered, and/or grown on low P soil
RELATION OF P REQT OF BEEF COWS IN
COMPARISON TO THE P CONCENTRATION
OF COMMON FORAGES
• Magnesium should be supplemented when cows are
grazing lush pastures in spring and fall
– Prevention of grass tetany
– Supplementation
• 0.6 oz Mg/day
• Forms
– MgO (1 oz/day)
– MgSO4 (3 oz/day)
– Do not feed dolomitic limestone
• If part of a complete mineral mix, must adjust intake to
attain 0.6 oz Mg/day
– Can be included in part of free choice mineral mix
• Loose mineral better than block
• Trace minerals
– Cu, Zn, Fe, Mn, Co, I, Se
• Cu has been a problem in the Midwest because of borderline soils,
increasing soil pH, and increasing Mo and S in forages
– Included in free choice mineral mix
– Organic forms of trace minerals may improve absorption,
but their use is not economical
– Cafeteria mineral feeding of trace minerals is not effective
VITAMIN SUPPLEMENTATION OF BEEF
COWS
• Vitamin A
– Only needed when consuming crop residues and
stored forages
– Need 30,000 IU/d when pregnant and 45,000 IU/d
during lactation
– May be supplied in complete supplement, in a free
choice vitamin-mineral supplement (500,000 IU/lb), or
by intramuscular injection (1 million IU/28 days)
• Vitamin D
– Not needed when cattle maintained outdoors
• Vitamin E
– Not needed
• B vitamins not needed by forage fed cattle