Nutrition Programs for Growing Nutrition Programs for Growing HeifersHeifers

José Eduardo P. Santos

VMTRC

Goals of a Nutrition Program for Growing Heifers

1. Achieve puberty and sexual maturity early

2. Achieve adequate body weight, height, and frame size at calving

3. Decrease age at first calving with adequate body size, without compromising mammary development and lactation performance

4. Economically sound

Feeding Program for Growing Heifers

Divided into:

Preweaning feeding program

Prepubertal feeding program

Postpubertal feeding program

The Dairy Production CycleThe Dairy Production Cycle

Maternity PenCalfCalf

Hutch/Calf penHutch/Calf pen

Group PensGroup Pens

WeaningWeaning

Breeding Age HeiferBreeding Age Heifer

Bred heiferBred heifer

Springing Heifer

FreshHigh Group

Medium Group

Low Group

Far-off dry cows

Close-up dry cows

Target Growth for Holstein Heifers

Prepubertal period: 3 to 9 months BW gain: 1.6 to 1.8 lbs/d Wither height: 1.4”/month

Breeding period: 13 months BW: 780 lbs 49 to 50” wither height BCS: 3.0 - 3.5

Postpubertal Period

10 months to calving BW gain: 1.8 to 2.0 lbs/d Wither height: 0.5 to 0.6”/month

Prepartum (22 - 24 months): BW: 1350 to 1400 lbs pre-calving or 1200 lbs

after calving Height: 54-56” at the withers BCS < 4.0 at calving (3.25 - 3.75)

Heifer Weight in Herds with Different Production Levels (Heinrichs and Losinger, 1998)

100200300400500600700800900

10001100

BW

, lb

3 6 12 18

Age, mo

< 16,000 16 to 20,000 > 20,000

Lactation Performance

Intrinsic factors that affect milk production during first lactation: Number of milk secreting mammary cells (Tucker,

1981)

GeneticsMammary development during the allometric

phase (Sejrsen and Purup, 1997)

Ability of the animal to compete for feed and to deliver nutrients to the mammary glandBody size

Mammary Gland Development

Four Phases: Fetal life:

Basic structure: stroma, circulatory system, and few ducts Isometric: first 60 to 90 days of life

Gland grows at the same rate of the body: stroma and blood vessels

Allometric: 3 to 9 months (puberty) Gland grows at a faster rate than the rest of the body: fat

pad and ducts (Sinha and Tucker, 1969) Determines the number of milk-secreting cells that will be

present during lactation Isometric: After puberty

Two Schools

European (Danish): Kris Sejrsen and colleagues Accelerated growth rates during the allometric phase is

detrimental to mammary development and milk yield potential

American: M. VanAmburgh, M. VandeHaar and others

Negative effects of accelerated growth rates during the prepubertal period can be overcome by diet formulation

Danish Data

Growth rates above 1.6 lbs/d during the prepubertal period:

Reduce parenchymal DNA in the mammary gland

Decrease milk production during first lactation (10 to 20% lower)

Mechanism: not clear, but seems to be associated with reduced sensitivity of mammary cells to IGF-I

Effect of Prepubertal Feeding Level on Milk Production (Hohenboken et al., 1995)

At Calving 250d-FCM

Breed n ADG,lb/d

Age,mo

BW lbs Relative, %

41 0.8 29 750 11,275 100DanishJersey 44 1.1 26 777 10,450 93

44 1.3 23 724 9,075 80

53 1.3 29 689 11,935 100DanishFriesian

53 1.6 26 1,100 11,880 100

55 1.9 23 1,096 10,780 90

Effect of ADG During Puberty on Mammary Gland Secretory Tissue

0

50

100

150

200

250

Par

ench

ymal

DN

A, m

g/10

0 lb

s of

B

W

Sejrsen et al., 1982 Petitclerc et al., 1984 Harrison et al., 1983

Low ADG High ADG

Ratio CP/ME < 55 g CP/Mcal ME

Effect of ADG During Puberty on Mammary Gland Secretory Tissue

100

125

150

175

200

225

250

275

300

Par

ench

ymal

DN

A, m

g/10

0 lb

s of

B

W

Capuco et al., 1995 Radcliff et al., 1997

Low ADG with Alfalfa High ADG with Alfalfa Low ADG with CS High ADG with CS

Ratio CP/ME

55

83

89 68

Effect of Prepubertal ADG on Performance During First Lactation (Van Amburgh et al., 1998)

60616263646566676869707172

Milk 3.5% FCM

1.5 lb/d 1.83 lb/d 2.1 lb/d

a

abb

aab

b

a,b P < 0.05

CP:ME = 62.3, 66.7, 63.5 g/Mcal

Recommendations

Formulate diets to achieve and ADG of 1.7 to 1.8 lbs/d

Adjust CP content of the diet Ratio CP to ME: 64 g/Mcal Hoffman (1998) suggested that protein quality

may be an issue. However, response to RUP sources is not consistent in growing heifers Maximize microbial protein

Data from Cornell University (Elrod and Butler, 1993)

Excess degradable protein in diets of breeding heifers might decrease conception ratesCP : 21%RDP = 82.5% of CP

CR dropped from 82 to 60%

Effect of Ionophores on Rumen Bacteria (Gram +)

Extracellular Intracellular ATP H+ H+

ADP

H+ H+

K+ K+

Na+ Na+

H+ H+

M

M

Rumen Fermentation

CHOProtein

MicrobialProtein + NH3

Glucose

Pyruvate

Propionate

Acetate + Butyrate

CO2 + CH4 +

H2

Use of Ionophores in Diets for Growing Heifers

Control coccidiosis

Ionophore-resistant bacteria (Gram - ) produce more propionate and less acetate Increase efficiency of energy utilization

Reduce DMI

May or may not increase ADG

Increase feed efficiency

May reduce age at puberty

Influence of Ionophores on Performance of Growing Cattle (167 trials with 11,414 animals)

-8

-6

-4

-2

0

2

4

6

DMI ADG F/G

Cha

nge,

%

Monensin Lasalocid Lanna (1997)

Guidelines for Feeding Growing Heifers

Adjust energy content of diets to promote an ADG of 1.7 to 1.8 lbs/d

ME content of the diet 1.0 to 1.2 Mcal/lb of DM

NEg: 0.40 to 0.45 Mcal/lb of DM

Energy requirements for breeding heifers: Maintenance: 780 lbs = 14 Mcal/d

1 lb of gain is equivalent to 4.3 Mcal of ME

Guidelines for Feeding Growing Heifers

Limit CP to no more than 16 or 17% for heifers with BW greater than 300 lbs

Maintain a CP:MP ratio of 64 g of CP for every Mcal of ME

Add Ionophores to the diet: Monensin: 200 to 300 mg/hd/d or 20 to 30 ppm

Lasalocid: 200 to 300 mg/hd/d or 20 to 30 ppm

Prepartum Heifers

Feed a high energy low NDF diet NEL: 0.72 to 0.75 Mcal/lb NDF: 32 to 35% NFC: 38 to 42%

Use high quality forages (Corn silage)

Avoid ingredients with high fat content dietary fat < 3.5%

Prepartum Heifers

Keep CP at 14 to 15% during the last 3 to 4 weeks prepartum

Close-up heifer group should be consuming 22 to 25 lb of DM/hd/d (1.6`- 1.7% of BW)

Feed a low Na and K diet to minimize udder edema

Cost of Feeding Replacements

California (1999 - 2000) 4 to 12 months:

$ 100.00 to 120.00/ton DM

13 to 23 months:$ 80.00 to $ 95.00/ton DM