The dry period

The basics

The dry period

• What is a dry period?

• Why do we need a dry period?

• The physiology of lactation

• The ideal length of the dry period

• Dry period management

• Udder health

Lactation

What is the dry period?

Dry PeriodHalting of

milk removal

Calving

Non-lactating period

LactationCalving

Lactating periodTo ensure milk production, cows must calve regularly

Lactation

Why do we need a dry period?

To ensure high milk production

Pregnant; No dry period Milk Production

Not Pregnant; No dry period

Dry PeriodHalting of

milk removal

Calving

Non-lactating period

Calving

Lactating period

This is a lactation curveMilk yield declines during lactation

The Udder - Anatomy

Epithelial cells in the udder need renewal

Number of mammary epithelial cells and their secretory activity determine shape of lactation curve

Number or activity of mammary

secretory cells

Milk yieldNumber or activity

of mammary secretory cells

Milk yield

Epithelial cells continuously die and renew

Apoptosis (cell death)

New cellCapuco and Akers, 1999

10 cells 10-2+1 9 cells(1 new)

Decreased milk yield due to:Declining cell numbers

Decreasing secretory capacity

We need a dry period

Capuco et al., 2003

The dry periodThree stages

Colostrum FormationColostrum Formation

Steady StateSteady State

InvolutionInvolution

Apoptosis (cell death)

Cell renewal

Cell renewal

New cells start secreting

Physiological cycle of lactation

Lactation

300-400 days

Involution

Steady state

Colostrum formation

Old cellsNew cells

More milk after a 60 day dry period

Bachman and Schairer, 2003

A 60 day dry period is idealOptimal length to ensure high milk production

Kuhn et al., 2006

Heifers need a 60 day dry period

Pezeshki et al., 2009

* * *

* Significant difference 56d and 35 d (p<0.05)

Short 30 - 40 day dry period

Improved energy balance (Rastani et al., 2005)

Suitable for older over-conditioned cows (Pezeshki et al., 2009)

Less time for dry cows to ‘grow’

Less milk after calving:• Especially in heifers• May be compensated by more milk before calving

Increased complexity• Heifers need a 60 day dry period (Pezeshki et al., 2009)

No margin in case of early calving• Very low milk production after calving, culling

AdvantagesAdvantages

DisadvantagesDisadvantages

Short dry periods are riskyMain reason why few farmers have adopted short dry periods

gestation

280 days220 days

start dry period

Dry period may be shortened unexpectedly

• Exact moment of calving is uncertain

• Cows with twins calve early or abort

• Cow may be pregnant from an earlier insemination

Planning a dry period that is long

enough provides

safety margin

The dry period

Good management is essential success factor for high production in late lactation

Cow comfortHygiene

Feeding

Udder healthThe key for prevention lies in the dry period

0

20

40

60

80

100

120

140

-10 -5 0 5 10 15 20 25 30

Days relative to calving

Cases per 10.000 cow-days at risk

HeifersCows

Recharge of udder healthCure and prevention of blanket antimicrobial DCT vs no DCT

Cure averages 71-85%(Halasa et al., 2009a)

Prevention averages 39%(Halasa et al., 2009b)

The dry period

• What is a dry period?

• Why do we need a dry period?

• The physiology of lactation

• The ideal length of the dry period

• Dry period management

• Udder health

Course Assessment

• 10 questions

• 80% to pass

• More than one answer can be right

• Click Submit button after each question

• If you exit assessment, you will have to restart

• Cumulative score displayed at the end

Question 1Why is milk production declining after peak lactation?

• Because cows eat less• Due to a negative balance of renewal and

apoptosis of epithelial cells• Because the number of alveoli is decreasing• After peak lactation cows are managed

differently

Question 2Why do we need a dry period?

• To give cows a break• To ensure high milk production• To renew epithelial cells• To prevent mastitis

Question 3Name the three physiological stages of the epithelial cells during the dry period

• Stop milking, no milking, calving• Involution , Steady state, Colostrum formation• Apoptosis, Renewal, Secretion• Feeding, Hygiene, Cow comfort

Question 4Why is 60 days the ideal length for the dry period?

• It ensures high milk production after calving• It provides enough time for the three

physiological stages • Gives cows enough time to rest• Provides enough time for the teats to recuperate

from milking• It provides a safety margin for early calving

Question 5What are the advantages of a short dry period?

• Provides a safety margin for early calving• Cows have less time to grow fat• It could help preventing metabolic disease• It is good for heifers• Milk production decreases

Question 6Does age play a role in the ideal dry period length?

• Yes, older cows need a longer dry period• No, age doesn’t matter• Yes, heifers need a longer dry period than older

cows• Yes, heifers need a shorter dry period than older

cows

Question 7Is good management during the dry period important?

• Yes, it helps the cow reach it’s genetic milk production potential

• Yes, otherwise the dry cow treatment does not work

• No, cows get new intramammary infections anyway

• No, in the dry period, the cows do not produce milk anyway

Question 8Why do we need dry cow treatment?

• To cure existing infections• To prevent new infections• To prevent clinical mastitis after calving • To ensure the renewal of epithelial cells

Question 9What are the high risk periods for new infections during the dry period

• During the steady state period• Around calving• Before dry off• Just after dry off

Question 10What can we expect from a dry cow treatment?

• Prevention of 100% of new infections• Cure of all existing infections at dry off• Prevention of around 40% of new infections• A reduction of the incidence of clinical mastitis

after calving