DAIRY HERD NUTRITION
pp. 435-442;
446-449
GOALS IN FEEDING A DAIRY HERD
• Maximize milk production
• Maintain reproduction
• Prevent metabolic diseases
– Ketosis
– Milk fever (parturient paresis)
– Displaced abomasum
• Control feed costs
• Minimize nutrient excretion
EARLY LACTATION
THE DAIRY COW’S DILEMMA
FACTORS AFFECTING DM INTAKE OF
DAIRY COWS
• Milk production
• Week of lactation
DMI, % BW
– Peak feed intake follows peak milk production
4.5
4
3.5
3
2.5
2
1.5
1
0.5
0
0
10
20
30
Week of lactation
40
50
• NDF concentration
• Fat concentration of diet
– Feeding > 5% fat reduces DM intake
• Worse problem with unsaturated fats
• Diet moisture
– Feeding diet > 50% moisture reduces DM intake
• Improper adaptation to high grain diet reduce DM
intake
• Metabolic diseases (ketosis or milk fever) reduce DM
intake
IMPLICATIONS OF CHANGES IN FEED INTAKE
OF DAIRY COWS
• Increase in feed intake follows increase in milk
production in early lactation
• High level of feed intake increases rate of passage
– A reduction in digestibility of 4% for each increase in DMI of
1x maintenance (Typically DMI will be 3x maintenace)
– Reduction greater on high grain diets than high forage diets
– Reduces ruminal protein degradability
Energy Requirement of Dairy Cows
• In lactating dairy cows, it has been shown that energy
is utilized for maintenance, lactation and pregnancy
with approximately equal efficiency
– 60 – 70% with an average of 64.4%
Lactation
BW gain
Energy 0
balance
Maintenance
Reqt 112 kcal ME
Or 73.5 kcal NE/kg.75
ME intake
• As a result, the energy requirements for all expressions
are expressed as one term, NEl
NET ENERGY REQUIREMENT FOR MAINTENANCE OF
DAIRY COWS
• Calculation
– NEl, Mcal/day= 0.08 kg BW.75
• Factor affecting maintenance
– Extra activity
• Flat pasture, close
• Hilly pasture, far
– Temperature
% increase
10
50
• Cold
– Assume NEl concentration of diet reduced by 8%
• Heat
– Assume a 25% increase in maintenance
– Pregnancy
• Day 190
• Day 270
– Growth
• 1st lactation
• 2nd lactation
% increase
60
86
% increase
20
10
NET ENERGY FOR MILK PRODUCTION BY
LACTATING DAIRY COWS
• NEl, Mcal/kg milk = .0929 x Fat% + .0347 x CP% +
.0395 x lactose%
• Example (Assume 3.4% CP and 5.8% lactose)
% fat
2.5
3.0
3.5
4.0
Mcal/kg
0.59
0.64
0.68
0.74
• Simply added to maintenance
NEL REQUIREMENTS OF 680 KG COW
PRODUCING 10,000 KG MILK/YR
FIBER REQUIREMENT OF DAIRY COWS
• Adequate fiber of the appropriate length is necessary to:
– Maintain milk fat percentage
– Maintain rumen health (Acidosis, Parakeratosis, Laminitis, Displaced
abomasum)
– Maintain feed intake
• Recommendations
– Minimum amount of forage = 40% DM
– 1989 NRC
• Minimum NDF = 28% (75% from forage)
• Minimum ADF = 18%
– 2001 NRC NDF requirement
Forage
Minimum NDF, %DM
19
17
15
Diet
Minimum NDF, %DM
25
29
33
• Adjustments in fiber requirement
– Starch source
• High moisture corn
• Barley
– Forage particle size
27% NDF (Minimum)
27% NDF (Minimum)
• Desire length of chop of forage at ¼”
15 to 20% of particles > 1.5”
– Method of feeding
• Feeding separate components will increase the NDF
requirement
– Dietary buffers
• Can lower NDF requirements
• Buffers (fed at 0.5 – 1.5% of DM)
– NaHCO3
– MgO
– KHCO3
• Unpalatable
• Will increase rumen pH, but doesn’t solve all problems
associated with low fiber
PROTEIN REQUIREMENTS OF LACTATING
DAIRY COWS
• Metabolizable protein requirement follows milk
production
– MP reqt, gm/d = (Maintenance + (Milk production, gm x
.036))/.67
• Meeting the protein requirements of dairy
cows
– Increase crude protein concentration and reduce
protein degradability in early lactation
• No NPN use
– Lower crude protein concentration and increase
protein degradability in mid- and late lactation
• NPN may be used in late lactation to limits
– Supply enough degradable protein to meet
microbial needs during dry period to 2 weeks
prior to freshening
• NPN may be used to limits
Ca AND P REQUIREMENTS OF DAIRY
COWS
• Ca and P requirements follow milk
production and pregnancy
PHASE FEEDING OF DAIRY COWS
EARLY LACTATION
• First 70 days of lactation
– First 3 weeks are most critical
• Relationship of intake and milk production
Week of peak
Milk production
6-8
Feed intake
8-12
• Results
– High producing dairy cows can’t meet energy
requirements and fiber requirements in early
lactation
• Implications
– Meet the cow’s fiber requirements and accept the
loss in cow weight.
• A dairy cow in good condition (BCS 3.5 on 5 point scale),
but not overly fat, can safely lose up to 15% of her
bodyweight in first 70 days.
• Energy mobilized from tissue related to BCS
BCS
Mcal NEl
2
375
3
399
4
417
5
432
• Example
– A cow at BCS 4 losing 1 BCS will produce
417 Mcal/0.74 Mcal/kg 4% FC milk = 564 kg FCM
• Cows should not be at a condition score >4 coming into
lactation
– Will be susceptible to ketosis and displaced abomasum
• Body weight lost should be replaced during late lactation
– Advantages
Efficiency
Stage of lactation ME to tissue Tissue to milk Total
Late lactation
75
82
61.5
Dry period
60
82
49.2
Diet to milk
64.4
– Additional advantages of replacing weight in late lactation
» Easier to feed grain to lactating cows
» Because of higher feed intake of lactating cows, easier
to meet fiber requirement while feeding grain
– Maximize feed intake
• Don’t have cows at BCS>4 (5 point scale)
• Use premium or supreme quality forage
• Properly adapt cow to grain
– Introduce to lactation grain mix 2 weeks before calving
– Increase grain mix at 1 lb/day in early lactation to
lactation diet
• Delay fat supplementation until week 5 to 7
• Do not feed DDGS at greater than 20% of the DM
– High fat and fiber
• Do not feed corn gluten feed at greater that 25% of the DM
– High fiber
– Increase concentration of CP, Ca, and P in diet
• Can’t mobilize these nutrients as readily as energy
• Utilize sources of rumen undegradable protein and
protected amino acids (lysine, methionine)
– Supplement
•
•
•
•
•
Salt
0.5 % DM
Trace mineral
Vitamin A
5,500 IU/kg DM
Vitamin D
1,500 IU/kg DM
Vitamin E
40 IU/kg DM
MID TO LATE LACTATION
• Mid lactation 70 to 140 days
• Late lactation 140 to 305 days
• Replace body energy stores
– Will cycle when positive energy balance occurs
• Balance diet to meet energy and nutrient
requirements
• Maximum Grain = 2.5% BW
• Minimum Forage = 1.5% BW
• Can utilize supplemental fat to increase energy
concentration
Supplemental fat source
Maximum fat in diet, %DM
Unprotected fat (Tallow)
5
Fat in seed (Soybean, Cottonseed)
7
Ca-salt of long-chain fatty acid
7
– Problems with excess fat
• Milk fat depression
– Trans-10, cis-12 linoleic acid produced from hydrogenation of
fatty acids in rumen of cattle fed high grain diets inhibits fatty acid
in the mammary gland
• Reduced feed intake
• Reduced milk protein
– Need to supplement RUP
• Reduced digestion of Ca and Mg
• Excessive fatness if BCS>3.5
– Can utilize NPN to limits
• No more than 1/3 of the diet CP
• No more than 1% of the diet DM
– Supplement
•
•
•
•
•
Salt
0.5 % DM
Trace mineral
Vitamin A
3,700 IU/kg DM
Vitamin D
1,000 IU/kg DM
Vitamin E
30 IU/kg DM
DRY PERIOD
• 60 or 45 days to 14 days pre-calving
• Goals
– Maintain body condition
• Prevent excessive fatness
• Feed a high forage diet
– Can use some lower quality for to dilute energy
• May have to limit feed
– Particularly corn silage
• Consequence of excessive fatness is ketosis
•
Ketosis-fatty acid liver
–
In early lactation, energy must be mobilized from tissue reserves
Excessive use of body fat
Lack of OAA
Lack of carnitine
Lack of niacin
Overcomes limit of triglyceride to be:
1.
transported from liver as VLDL
2.
oxidized in TCA cycle in liver
Fat accumulates
in hepatocytes
(Fatty liver)
Acetyl-CoA
Acetoacetate
B-OH-Butyrate
Impairs feed intake
Reduced
milk
production
Impairs gluconeogenisis
Appear in milk
Increased milk fever
Increased displaced abomasum
Increased retained placenta
Increased mastitis
Reduces
glucose
– Ketosis prevention
• Avoid excessive fatness in cows (BCS>4)
• Maximize intake immediately before and after
calving
– Avoid abrupt change to high grain lactation diet at
calving
– Feed balanced ration
– Use high quality forages
• Drench cows with propylene glycol (1L/day) for
1 week daily before calving
– Propylene glycol is metabolized to lactate that can be
used for gluconeogenisis
• Supplement with nicotinic acid (6 – 12 g/d)
– Increases DMI
– Reduces lipolysis
– Recommendations
» Use in ketosis prone cows
» Use from 14 days prepartum to 120 days
postpartum
» Use palatable carrier
– Prevention of milk fever
• Milk fever (parturient paresis)
Serum Ca, mg/100
Normal
10
Milk fever
4.6
• Occurs immediately before or after calving
• Caused by failure of Ca homeostasis
– Reduced calcium absorption from small intestine
– Reduced mobilization of Ca from bone
– Both result from alkalosis caused by a high
concentration of cations relative to anions in diet
• Prevention
– Reduce cation-anion difference
» Creates metabolic acidosis
– DCAD = ([Na+] + [K+] + .15[Ca+2] + .15[Mg+2])
- ([Cl-] + .6[S-2] + .5[P-3])
Methods to decrease DCAD during dry period
• Decrease concentration of cations (particularly K) in
diet
– K is the cation in highest concentration in dairy rations
– Factors affecting dietary K levels
•
•
•
•
•
Legumes > Grasses
Immature > Mature
Leaves > Stems
Heavily fertilized > Unfertilized
High temperatures > Cool temperatures
Dietary Ca, %
.5
1.5
.5
1.5
Urine pH
1.1
5.8
5.7
Dietary K, %
2.2
3.1
8.0
8.1
7.9
8.2
Milk fever incidence 0/10
2/10
- Decrease Na concentration in diet
- Decrease Ca concentration of diet???
4/11
6/9
8/10
3/13
Method of decreasing DCAD (Continued)
• Adding anions to diet
– Commonly added anions
•
•
•
•
•
•
•
CaCl2
Ca propionate
Ca SO4
NH4Cl
(NH4)2SO4
MgCl2
MgSO4
– Unpalatable and may causes ulcers in mouth and GI tract
– Monitor urine pH
• Desired range 6.2 – 6.8
– CaCO3, PO4 salts and elemental S are ineffective
– Recent studies increasing the anion content of forages by
fertilizing with CaCl2 shows promise
– Do not use on heifers
• Return to positive DCAD after calving
• Other considerations in dry period nutrition
– Feed 12% CP
• To maintain rumen microbial growth
– Feed 60 to 80 gm Ca/day
– Feed 30 to 40 gm P/day
– Limit salt to 28 gm/day
• To prevent udder edema
– Vitamin A
– Vitamin D
– Vitamin E
5,500 IU/kg DM
1,500 IU/kg DM
40 IU/kg DM
TRANSITION PERIOD
•
•
•
•
2 weeks pre-calving
Feed lactation grain mix up to .5 to 1.0% BW
Maintain long hay at .5 to 1.0% BW
Limit corn silage to 1.0% BW