Dairy Cattle Nutrition
Dairy Cattle Nutrition
Focus will be split between:
Practical aspects of evaluating feeding programs
Unique considerations in diet formulation
Average Milk Production per Cow
Dairy Cattle Nutrition
25000
US
20000
IA
M i l k p e r C o w (l b s )
Life cycle nutrition
15000
– birth to weaning
Heifers
– weaning to prepre-calving
Dry cows
5000
0
19
19
80
65
Lactating cows
10000
95
Calves
19
Four basic groups
Year
US average milk/cow/year
Iowa DHI averages by breed - 2009
all
1965
8,305 lb
1975
10,360 lb
Ayr
No. herds
BS
Gue
Hol
Jer
Other
herds
12
29
11
666
33
97
7201
Milk (lb)
18,076
18,599
15,927
21,806
15,244
18,478
20,997
E C M (lb)
21,496
1985
12,994 lb
18,817
20,163
18,273
22,050
18,016
19,441
1995
16,433 lb
Fat (lb)
696
756
725
799
720
720
785
2005
19,576 lb
Fat %
3.94
4.30
4.66
3.77
4.96
4.08
3.89
Protein (lb)
2009
20,997 lb
569
626
535
667
541
593
650
Protein %
3.23
3.42
3.49
3.13
3.69
3.33
3.19
CFP (lb)
1264
1382
1262
1466
1261
1314
1436
F:P ratio
1.22
1.21
1.36
1.20
1.59
1.21
1.21
1
Top 10 Iowa Herds in 2009
Rolling herd average milk production
Top 10 Iowa Herds in 2008
Herd sizes for top 10 herds (RHA milk production)
1.
32,566 lb/cow/yr
1.
2.
31,566
2.
596
3.
31,511
3.
421
4.
31,252
4.
135
5.
30,701
5.
126
6.
30,422
6.
120
7.
30,399
7.
84
8.
30,334
8.
77
9.
30,259
9.
45
10.
29,928
10.
34
Reasons for increase in production per cow
1,177 cows
Reasons for increase in production per cow
Improved genetics
Reasons for increase in production per cow
Reasons for increase in production per cow
Improved genetics
Improved genetics
only species where individual animal performance
measured on a daily basis
Improved forage and feed quality
DHI program available over 100 years
USDA-AIPL genetic evaluation of AI sires over 50 years
- with genomic testing I expect this trend to accelerate
2
Reasons for increase in production per cow
Reasons for increase in production per cow
Improved genetics
Improved genetics
Improved forage and feed quality
Improved forage and feed quality
improved varieties
Improved feeding & management practices
improved harvest management
increased utilization of TMRs
processing corn silage
enhanced transition cow management programs
more focused on cow comfort
Keys to success
Milk Production
Daily milk and DM Intake
1. Keep the cows healthy and on feed
1
3
5
7
9
11
13
15
17
19
21
23
25
27
29
31
33
35
37
39
41
43
45
47
49
51
We ek of Lactation
Keys to success
Milk Production
1. Keep the cows healthy and on feed
Daily milk and DM Intake
2. Maximize/optimize dry matter intake
1
3
5
7
9
11
13
15
17
19
21
23
25
27
29
31
33
35
37
39
41
43
45
47
49
51
Wee k of Lactation
3
Dry matter intake
Milk Production & Dry Matter Intake
Daily milk and DM Intake
Factors used to estimate DMI:
body weight
milk production
fat test
days in milk
1
3
5
7
9
11
13
15
17
19
21
23
25
27
29
31
33
35
37
39
41
43
45
47
49
51
Wee k of Lactation
Dry matter intake
Milk production
Dry matter intake
Dry matter intakes (lb)
The 2001 NRC equation to predict dry matter intake (DMI) for
lactating cows is:
DMI = (((BW ^ 0.75) * 0.0968) + (0.372 * FCM) - 0.293) * Lag
Low intake in early lactation is adjusted using the Lag variable for
lactating cows:
Week
Lact. 1
Lact. 2 & over
1
31.0
36.5
2
35.0
42.5
3
38.0
46.5
4
40.0
49.0
5
41.5
52.5
Lag = 1 – exp(-0.192 * (WOL + 3.67))
Keys to success
Dynamics of the Lactation Cycle
Body Weight
Daily milk and DM Intake
1. Keep the cows healthy and on feed
2. Maximize/optimize dry matter intake
utilize high quality forages
maintain adequate level of effective fiber
minimize sorting of ration
1
3
5
7
9
11
13
15
17
19
21
23
25
27
29
31
33
35
37
39
41
43
45
47
49
51
Week of Lactation
Dry matter intake
Milk production
Body w eight
4
Nutrient composition of alfalfa
Stage of
maturity
Alfalfa maturity / milk yield
CP
ADF
NDF
NE-l
------ % of dry matter -------- Mcal/lb
RFV
Alfalfa
Maturity
Grain fed
% of DM
Prebloom
21.1
30.2
40.5
.67
150
Prebloom
20
Early bloom
18.9
33.0
42.0
.64
140
Early bloom
37
Mid-bloom
16.3
38.0
52.5
.58
105
Mid-bloom
54
Full bloom
14.7
45.9
59.5
.48
83
Full bloom
71
Milk production
Grain fed
% of DM
20
Milk production
Pre
Early
Alfalfa Maturity
Mid
Full
78.8
Grain fed
% of DM
Pre
20
78.8
37
37
83.2
54
54
87.1
71
71
88.0
Alfalfa Maturity
Mid
Full
Formulating Rations for Lactating Cows
Milk production
Grain fed
% of DM
Early
Alfalfa Maturity
Mid
1. Measuring forage quality
Pre
Early
Full
20
78.8
68.0
57.2
52.1
37
83.2
69.1
62.5
55.4
54
87.1
77.2
66.2
64.7
71
88.0
77.2
64.7
69.1
5
Plant Carbohydrates
Formulating Rations for Lactating Cows
Cell Contents
Cell Wall
NonStructural Carbohydrates
Structural Carbohydrates
1. Measuring forage quality
Proximate analysis (wet chemistry) vs. NIR
Organic Acids
Sugars
Starches
Fructans
Pectin
ß-Glucans
Hemicellulose
RFV vs RFQ
Lignin
PEAQ
Neutral Detergent Fiber
Non-fiber Carbohydrates
Effective fiber
Acid Detergent Fiber
Nonstructural Carbohydrates
Very rapid
Cellulose
Rumen Microbial Fermentation Rates
Very Slow
Proximate Analysis
Proximate Analysis
Weende System of Proximate Analysis
Proximate Analysis
Detergent System
1.
Water (DM)
1.
Water (DM)
Water
2.
Crude protein (CP)
2.
Crude protein (CP)
CP
3.
Crude Fiber
3.
Crude Fat
EE
4.
Crude Fat
4.
Crude Fiber
NDF (and ADF)
5.
Ash
5.
Ash
Ash
6.
Nitrogen-free extract
6.
Nitrogen-free extract
Weende System
(Proximate analysis)
Ash (1)
Ether extract or Crude fat
Crude protein
Nitrogen-free extract
- calculated by difference
Chemical
Component
Van Soest System
Soluble ash
Relative forage value
Neutral
detergent
solubles
Lipids, pigments, etc
older system
index of feeding value based on intake & digestibility
Protein, NPN, etc.
NDF to estimate intake
Sugars, starch, pectin
ADF to estimate digestible dry matter
Hemicellulose
Alkali-soluble lignin
Crude fiber
Neutral
detergent
fiber
Acid
detergent
fiber
Alkali insoluble lignin
Cellulose
Ash (2)
Insoluble ash (silica)
RFV & RFQ
Ash
6
RFV
RFV
NDF negatively correlated with intake
Primary use is quality tested hay auctions
DMI (as % of BW) = 120 / Forage NDF %
Used at ISU dairy for many years
ADF negatively correlated with digestibility
vendors bid price for RFV = 150
DDM % = 88.9 – (0.779 X ADF %)
bonus: $1.00/point above RFV=150
penalty: $2.00/point below RFV=150
RFV = (DDM X DMI) / 1.29
(1.29 selected so full bloom alfalfa RFV = 100)
RFQ
NDF digestibility
Includes digestibilities of NDF and dry matter
Immature grass hay (G)
dig DMI = NDF + ((dNDF – avg. dNDF) X 0.374)
Mid-maturity grass-legume mixture (GL)
dig DM = TDN = tdCP + (tdEE X 2.25) + tdNDF + tdNFC – 7
Mature legume hay (L)
Intl. feed no. 1-02-212
Intl. feed no. 1-02-277
Intl. feed no. 1-07-789
RFQ = (dig DMI X dig DM) / 1.23
1.23 chosen so mean and range of RFQ similar to RFV
Chemical composition (%)
NDF composition (%)
G
GL
L
G
GL
L
NDF
49.6
50.8
50.9
Hemicellulose
18.2
15.0
11.4
ADF
31.4
35.8
39.5
Cellulose
27.5
30.1
32.2
Lignin
3.9
5.7
7.3
Lignin
3.9
5.7
7.3
7
PEAQ
NDF digestibility
G
GL
L
TDN % (1X)
63.1
58.8
54.7
NE-L mcal/kg (3X)
1.37
1.25
1.13
NE-L mcal/kg (4X)
1.29
1.17
1.06
Predictive Equations for Alfalfa Quality
used to estimate RFV/RFQ of alfalfa standing in field
1. Choose representative 2-square-foot area in field
2. Determine most mature stem in sampling area
3. Measure height of most mature stem in sampling area
4. Repeat above steps for at least 5 locations
PEAQ
Maturity stages:
Late vegetative – no buds visible
Bud stage – 1 or more nodes with visible buds – no flowers
Flower stage – 1 or more nodes with open flowers
Height measured from ground to tip of the stem (not leaf blade)
PEAQ
Loose 10-20 RFV points during harvest, so…..
PEAQ
Height
Bud
Vegetative
Flower
inches
RFV
RFV
RFV
16
237
225
210
18
224
212
198
20
211
201
188
22
200
190
178
24
190
181
170
26
180
172
162
28
171
164
154
30
163
156
147
Effective fiber
Differs from chemical fiber (e.g. ADF and NDF)
Indication of cud chewing & rumen function
if want 180 RFV hay – cut when RFV = 200 for standing crop
Penn State Particle Separator
wet
Miner Institute ‘Z’ box
wet
ASAE Separator (5 sieves)
wet
Ro-Tap (9 sieves)
dry
8
Penn State Particle Size Separator boxes
Evaluate particle size distribution of TMR
target 5 – 10% on top
(can sort if > 12 - 15%)
> 40% in middle
< 50% in bottom pan
Penn State Particle Size Separator boxes
Concept of effective fiber
Applications –
Formulate diets for NDF
1.
Evaluate current ration for particle size distribution
Stimulate adequate cud chewing
2.
Check for sorting
Evaluated by measuring milk fat %
3.
Check consistency within a mixer load
4.
Check consistency from day-to-day
(risk of acidosis if > 55%)
Z-box to estimate peNDF
Physical fiber important for
Insufficient effective fiber
Cud chewing
Erratic dry matter intake
Saliva production
Lower milk fat %
Ruminal buffering
Decreased milk yields
Rumen motility
Health problems (DAs, ketosis, laminitis)
9
On-farm Evaluation Tools
1.
PSPSS
2.
Z-box
3.
BCS
4.
Locomotion scoring
5.
Manure scoring & screening
6.
Cud chewing
LOCOMOTION SCORING
•
Based on observation of cows standing and walking (gait)
with special emphasis on their back posture
•
Effective for early detection of claw disorders, monitoring
prevalence of lameness, comparing the incidence and
severity of lameness between herds and identifying cows for
functional claw trimming
DAIRY CATTLE LOCOMOTION SCORING
CLINICAL DESCRIPTION:
NORMAL
LOCOMOTION SCORING
•
•
•
•
Scoring from 1 to 5 (none to severe)
Evaluate the cow
– Levelness of the top line while standing
– Levelness of the top line while walking
– Evidence of favoring one or more feet
Score 30 to 50 cows per group
Calculate an average score
• Stands and walks normally, back flat walking and standing
• All feet placed with purpose
R DC - 319
DAIRY CATTLE LOCOMOTION SCORING
DAIRY CATTLE LOCOMOTION SCORING
CLINICAL DESCRIPTION:
CLINICAL DESCRIPTION:
MILDLY LAME
MODERATELY LAME
5% Milk Loss!
• Stands with flat back, but arches when walks
• Gait is slightly abnormal
R DC - 320
Adapted from Sprecher et al., 1997. Theriogenology 47:1179
Adapted from Sprecher et al., 1997. Theriogenology 47:1179
• Stands and walks with an arched back
P.H. strides
Robinson, Ph.D.,
Dept. of one
Animal Science,
UC Davis legs
• Short
with
or more
R DC - 321
Adapted from Sprecher et al., 1997. Theriogenology 47:1179
10
DAIRY CATTLE LOCOMOTION SCORING
DAIRY CATTLE LOCOMOTION SCORING
CLINICAL DESCRIPTION:
CLINICAL DESCRIPTION:
LAME
SEVERELY LAME
17% Milk Loss!
36% Milk Loss!
• Arched back standing and walking
• One or more limbs
favored
but
at least
weight bearing
P.H. Robinson,
Ph.D., Dept.
of Animal
Science, partially
UC Davis
R DC - 322
Adapted from Sprecher et al., 1997. Theriogenology 47:1179
• Arched back, refuses to bear weight on one limb
• May refuse orP.H.
have
great
difficulty
moving
Robinson,
Ph.D., Dept.
of Animal Science,
UC Davisfrom lying position
R DC - 323
Adapted from Sprecher et al., 1997. Theriogenology 47:1179
Lameness
Score
Goal
Milk Drop
DMI drop
1
2
3
4
5
75 %
15 %
9%
< 0.5 %
< 0.5 %
none
none
5%
17 %
36 %
none
1%
3%
7%
16 %
Goal is for herd average < 1.4
Lameness
Manure scoring
1
2
Score
3
Economic loss
($/cow annually)
Avg
Score
75
15
9
Goal
(1.4)
50
30
15
4
1
62
(1.8)
40
25
22
10
3
82
(2.1)
25
25
30
15
5
115
(2.5)
4
5
<0.5 <0.5
1 – Splash & Splatter
2 – Loose
3 – Average or Normal
4 – Firm
5 – Thud or Crash
11
Manure scoring
Manure scoring
1 - very liquid - diarrhea, consistency of pea soup
2 - runny, does not form distinct pile
associated with excess protein or starch, too much mineral,
or lack of fiber
associated with cows on lush pasture, or lack of fiber
Manure scoring
Manure scoring
3 - porridge-like appearance, will stack-up 1.5-2 in
4 - thicker, stacks up over 2 in
considered optimal
Manure scoring
5 - firm fecal balls
associated with dry cows and heifers
Manure screening
take ~ 1 cup of fresh manure
use #8 screen
associated with feeding straw-based diet, dehydration, or
intestinal blockage
wash with pressurized water
12
Manure screening
Look for undigested, whole corn kernels, whole soybeans, and
whole cottonseeds
If found, then inadequate processing or incomplete fermentation in
rumen
Cud chewing
Why is it important?
Cud chewing
Observe the herd 2 hours after the last feeding
- want 60% of the cows lying down & chewing their cud
Other Evaluation Tools
1.
Fat-protein ratios
2.
MUN levels
3.
150-day milk production
13
Fat-Protein Ratio ISU Herd
25.0
150-day milk production
20.0
Percent of Cows (%)
Adjusts the production of all cows to
150 days in milk
15.0
age (lactation number)
% fat and % protein
10.0
Allows comparison of management changes from one month to
the next
5.0
0.0
0.7
0.8
0.9
1.0
1.1
1.2
1.3
1.4
1.5
1.6
1.7
1.8
1.9
2.0
2.1
2.2
Fat - Protein Ratio
High producing cows
High producing cows
Biggest challenge...energy
Biggest challenge...energy
feed more concentrates
corn, barley, wheat, etc.
can you avoid acidosis (SARA) ?
High producing cows
Corn
Corn hybrids developed to withstand handling
Biggest challenge...energy
contain more vitreous endosperm rather than floury endosperm
feed more concentrates
feed supplemental fats & oils
oilseeds, choice white grease
watch level of saturated vs. unsaturated fats
can you avoid rumen digestive upsets?
14
Corn
Corn
Starch is protected by prolamin protein (zein)
increases as kernel matures
prolamin proteins must be broken down for digestion
break down by steam flaking or fine grinding
leads to heavier bushel weights
very insoluble in rumen
difficult to digest in small intestine
Corn Silage
becomes soluble in acid medium making starch available
CS often “feeds” better in March than in October
High Moisture Corn
Evolution of selection
Not a homogenous product
Grain yield per acre
different moisture (20% - 40%)
Later total tonnage of silage per acre (forage)
with or without inoculants
More recently considered fiber digestibility
ensiled whole or ground
may contain cobs and/or husks
Largely ignored availability of starch (lacked assays)
7 hour in-vitro starch digestibility assay by Mich State
fermented for varying lengths of time
stored in bags, bunkers and silos (some oxygen limiting)
Spartan 3 uses 7 hr in-vitro value
CPM & CNCPS use rate of digestion (Kd’s)
High Moisture Corn vs Dry Corn
NE-l of HMC 5-10% higher
High Moisture Corn
Optimal utilization of starch
Ruminal starch digestion is 20-30 percentage units higher
26 – 30% moisture roll
Rate of ruminal starch digestion is faster
20 – 24% moisture finely grind
> 30% moisture increased risk of acidosis
15
“Extra” nutrients wasted due to not being digested
“Extra” nutrients wasted due to not being digested
Ruminal starch degradability increases as particle size decreases
Ruminal starch degradability increases as particle size decreases
Mean
Particle
Size
Effective
Rumen
Degradability
(microns)
(%)
Cracked corn
“Chick” cracked
Fine ground
4309
2577
686
44.6
53.3
64.5
Steam-flaked
2896
75.4
Mean
Particle
Size
Dry ground
Dry rolled
High moisture ground
High moisture rolled
Effective
Rumen
Digestibility
Total
Tract
Digestibility
(microns)
(%)
(%)
618
1725
489
1789
60.9a
69.2a
86.8b
81.2b
88.9
76.4
98.2
95.7
Lykos and Varga (1995)
Knowlton, et al (1998)
Starch digestibility of corn silage
Processing so cows get more out of their feed
TLC (inch)
¾
¾
1
1
2
8
2
8
Starch digestibility (%) 79.4
83.1
75.8
87.7
75.3
NDF digestibility (%)
20.1
29.7
30.6
35.4
23.2
Milk (lb/d)
78.0
79.6
79.4
83.6
75.2
ECM (lb/d)
81.0
81.0
82.9
83.8
75.7
Roller clearance (mm)
¾
--
Cooke and Bernard (2005)
Starch digestibility of corn silage
Handling and storage considerations to reduce losses
TLC (inch)
¾
¾
¾
1
--
2
8
2
8
Starch digestibility (%)
79.4
83.1
75.8
87.7
75.3
NDF digestibility (%)
20.1
29.7
30.6
35.4
23.2
Milk (lb/d)
78.0
79.6
79.4
83.6
75.2
ECM (lb/d)
81.0
81.0
82.9
83.8
75.7
Roller clearance (mm)
1
Cooke and Bernard (2005)
16
Density of haylage stored in various structures
Density of corn silage stored in various structures
Storage
Units
Samples
Average
Range
SD
Bunker
31
91
15.9
9.9-27.2
3.5
Pile
14
39
13.7
8.2-22.9
3.4
Bunker/pile
3
9
22.2
14.7-36.3
7.7
12’ bag
1
2
10.7
9.5-11.8
1.6
10’ bag
14
34
13.0
3.4-24.8
5.2
9’ bag
15
30
12.0
4.3-27.2
5.3
8’ bag
1
2
12.1
8.3-15.9
5.4
Storage
Units
Samples
Average
Range
Bunker
37
120
12.1
6.4-23.6
SD
3.0
Pile
21
62
11.0
4.9-18.7
2.6
Bunker/pile
11
35
12.2
4.9-18.6
2.8
12’ bag
3
8
7.0
3.2-12.5
3.2
10’ bag
10
20
9.8
5.7-13.5
2.6
9’ bag
15
31
8.6
2.4-13.9
2.7
8’ bag
1
2
8.1
5.7-10.5
3.4
Visser (2005)
Visser (2005)
Strategies to reduce shrink…..
Silage bags
Strategies to reduce shrink…..
It could be worse….
17
Sources of shrink…..
Bunker silos – side spoilage
need to make a bag out of your bunker
4”-6” drain pipe along bottom edge of sidewall
plastic along inside wall, drape over top when filling
fold over top of silage after filling & before covering
rainwater will run off top, down sidewall between wall & plastic,
then exit via drain pipe
Sources of shrink…..
Bunker silos – spoilage at feed-out
Lactobacillus buchneri
- bacterial inoculant that reduces growth of yeasts
- produces acetic (and some lactic) acid during fermentation
- acetic acid inhibits growth of yeast that cause heating upon
exposure to oxygen
Using Infrared Thermography to
Demonstrate Product Performance
Treated
Control
This picture was taken of bunker face at the beginning of August, 2006
Using Infrared Thermography to
Demonstrate Product Performance
Treated
Control
This IR picture was taken of bunker face at the beginning of August, 2006
18
Formulating Rations for Lactating Cows
Formulating Rations for Lactating Cows
1.
Forage quality is key
1.
Forage quality is key
2.
Energy – can we meet the cow’s needs?
2.
Energy – can we meet the cow’s needs?
Excessive loss of body condition
Minimizing ketosis
Avoiding acidosis
Feeds which provide more energy
corn & other cereal grains (starch)
oil seeds (soybeans, cottonseeds, canola, sunflowers)
fats, oils, and grease
Starch content of common feeds (% of DM)
Soy hulls vs corn & SBM
Corn grain
70-75%
Wheat bran
22-26%
Soy
Shelled
44%
Wheat grain
62-65%
Wheat midds
18-26%
hulls
corn
SBM
Ear corn
55-62%
Corn gluten meal 15-18%
CP
13.9
9.4
49.9
Barley grain
50-56%
Corn germ meal
15-18%
RUP
45.0
47.0
35.0
Hominy
50-55%
Corn gluten feed
14-18%
ADF
44.6
3.4
10.0
Oat grain
40-44%
NDF
60.3
9.5
14.9
Corn silage
20-45%
Fat
2.7
4.2
1.6
TDN
67.3
88.7
80.0
Formulating Rations for Lactating Cows
Formulating Rations for Lactating Cows
1.
Forage quality if key
1.
Forage quality if key
2.
Energy – can we meet the cow’s needs?
2.
Energy – can we meet the cow’s needs?
Limit on feeding supplemental fats or oils
Avoiding acidosis (SARA)
1.0 - 1.25 lb of supplemental fat and oil (< 6% of DM)
(whole soybeans, whole cottonseed, fat, etc.)
any additional must be rumen protected
(Megalac, Energy Booster, Boster Fat, etc.)
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SARA
Formulating Rations for Lactating Cows
- inadequate effective fiber
- irregular feeding schedule
- change in forage moisture content
1.
Forage quality if key
2.
Energy
3.
Protein
Understanding RDP and RUP
- ration formulation errors
Want to maximize rumen microbial protein production
Consider the limiting amino acids for milk production
- high fat content of ration
Protein
Milk urea nitrogen
‘Good’ rumen degradable protein feeds
Protein (nitrogen) metabolism in the rumen
‘Good’ rumen undegradable protein feeds
Cause of high/low MUN levels
Optimum levels 12 mg/dl (10-14)
ISU Herd - MUN Levels
80
70
60
No. Cows
50
40
30
20
10
0
5
6
7
8
9
10
11
12
13
14
15
16
17
MUN (mg/dl)
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Formulating Rations for Lactating Cows
Water intake
1.
Forage quality if key
2.
Energy
Influenced by
eating pattern
3.
Protein
water temperature
4.
Water
offered in trough or bowl
quantity (intake)
delivery rates
quality
animal dominance if bowls shared
stray voltage
Grouping 2-yr olds
Grouping 2-yr olds
Together
Separate
Eating time, min/d
184
205
Meals per day
5.9
6.4
Resting time, min/day
424
461
Resting periods/day
5.3
6.3
Thumb rules
Formulating rations for 2-yr olds
- add 15-20# to their average
- formulate like an older cow
e.g. –
2-yr old @ 80# & older cow @ 100#
would be fed the same diet
DMI, lb/day
Together
Separate
39.2
44.5
Milk yield, lb/day
40.5
44.0
Milk fat, %
3.92
3.97
Thumb rules
# groups
balance for
1
avg. + 30%
2
avg. + 20%
3 or more
avg. + 10%
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A note on feeding replacements…
A note on feeding replacements…
Need to feed well enough for adequate growth rates
want to breed at 12-15 months of age
when to breed based on weight – not age
Need to feed well enough for adequate growth rates
want to breed at 12-15 months of age
Be very careful not to get prepuberal heifers too fat!
Pregnant heifers are easiest group to feed
large enough to utilize a lot of forage
relatively low protein requirement
opportunities exist to save $$$ on feed bill
primary concern is for heifers to not get too fat
Formulation of dairy rations vs. other species
Considerations for dairy:
Questions?
1. Digestibility of NDF
2. peNDF
3. Amount & digestibility of starch
4. Maximize rumen microbial protein production (RDP & RUP)
5. Supplement rumen protected lysine & methionine
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