Recent trends in mastitis and fertility indicators in the United States and reasons for change

H. Duane Norman

Animal Improvement Programs LaboratoryAgricultural Research Service, USDA Beltsville, MD 20705-2350, USA

[email protected]

EAAP – 2010 (1)

Recent trends in mastitis and fertility indicators in the United States and reasons for change

Session 18 Abstr. 7375

NormanEAAP – 2010 (2)

Mastitis indicators

Source: Purdue Dairy Clipart

Source: Dairy Herd Management


International BT-SCC limits

Country/group Limit (cells/ml)Australia 400,000Canada 500,000European Union 400,000New Zealand 400,000Norway 400,000Switzerland 400,000United States 750,000

California 600,000


U.S. milk quality measures

Bulk tank somatic cell count (BT-SCC)

Monitored by U.S. Department of Agriculture

Data from 4 of 10 Federal Milk Marketing Orders (FMO)

Accounts for nearly 50% of US milk supply

Herd test-day somatic cell count (TD-SCC)

Herds in Dairy Herd Improvement (DHI) somatic cell testing

Accounts for 97% of US DHI herds


318311

316322 320 319

295 296288

276

262

233

200

225

250

275

300

325

350

98 99 00 01 02 03 04 05 06 07 08 09

Year

SCC

(1

00

0s)

DHI TD-SCCFMO BT-SCC

U.S. SCC (all breeds)


U.S. herd size and SCC

100

125

150

175

200

225

250

98 00 02 04 06 08Year

Cow

s/herd

(no.)

200

225

250

275

300

325

TD

-SC

C (1

000s)


U.S. herd milk yield and SCC

9,000

9,250

9,500

9,750

10,000

10,250

98 00 02 04 06 08Year

Milk

(kg

)

200

225

250

275

300

325

TD

-SC

C (1

000s)


SCS used by U.S. DHI as a mastitis indicator

Simplicity

Desirable statistical properties (nearly normal distribution)

Conversion equations

SCS = log2(SCC/100,000) + 3

SCC = 2(SCS − 3)(100,000)

Somatic cell score (SCS)

SCS

SCC(cells/ml)

0 12,5001 25,0002 50,0003 100,0004 200,0005 400,0006 800,0007 1,600,00

08 3,200,00

09 6,400,00

0


SCS and change in herd size

2.50

2.75

3.00

3.25

3.50

99 01 03 05 07 09Year

SCS

DecreaseIncrease 1-49%Increase 50-99%Increase ≥100%


200

225

250

275

300

325

98 00 02 04 06 08

Year

SCC

(1000s)

U.S. and Canadian SCC

U.S. TD-SCC

QuébecBT-SCC

OntarioBT-SCC


150

200

250

300

350

400

90 92 94 96 98 00 02 04 06 08

Year

SCC

(1000s)

U.S. and New Zealand SCC

U.S. TD-SCC

New ZealandTD-SCC


200

225

250

275

300

325

350

94 96 98 00 02 04 06 08

Year

SCC

(1000s)

U.S. and Irish SCC

U.S. TD-SCC

Irish BT-SCC


German SCC

“No increase or decrease in SCC for German Holsteins across time”

– Reinhard Reents(personal

communication, 2010)


U.S. versus E.U. SCC monitoring

Individual farmIndividual farmSCC sample

2 consecutive3-month means over limit

3 of 5 consecutive samples over limit

Producer suspension

Geometric mean of 3 monthly BT-SCC

Consecutive monthly BT-SCC

Value used

400,000 cells/ml750,000 cells/mlBT-SCC limit

E.U.U.S.Program characteristic


Export concerns

E.U. change in SCC sampling point from bulk truck or plant silo to individual farm (October 1, 2010, enforcement)

3-month mean (E.U.) used as single reference for period, which allows more time to reduce future SCC

Geometric mean (E.U.) mathematically lower than arithmetic mean (U.S.) and requires recalculation


Geometric versus arithmetic means

SCC (cells/ml)

Example 1

Example 2

Month 1 400,000 300,000Month 2 500,000 400,000Month 3 600,000 700,000

Arithmetic mean 500,000 467,000Geometric mean 493,000 438,000


Fertility indicators

Source: English Guernsey Cattle SocietySource: BBC (Louise Cassidy)


75

80

85

90

95

100

98 00 02 04 06 08

Breeding year

Days

to 1

st b

reed

ing

Holstein

Jersey

U.S. days to 1st breeding


75

80

85

90

95

100

98 00 02 04 06 08

Breeding year

Days

to 1

st b

reed

ing

U.S. Holstein days to 1st breeding

– – – 1st parity

–––– All parities


75

80

85

90

95

100

98 00 02 04 06 08

Breeding year

Days

to 1

st b

reed

ing

U.S. Jersey days to 1st breeding




Holstein– – – 1st breeding–––– All breedings

Jersey– – – 1st breeding–––– All breedings

U.S. non-return rates (70 days)

40

45

50

55

60

98 00 02 04 06 08

Breeding year

Non-r

etu

rn r

ate

(%

)


Holstein– – – 1st breeding–––– All breedings

Jersey– – – 1st breeding–––– All breedings

U.S. conception rates

20

25

30

35

40

45

98 00 02 04 06 08

Breeding year

Conce

pti

on r

ate

(%

)


U.S. heifer and cow conception rates Genetic evaluations implemented

Bulls – January 2009 Cows – August 2010

Single-trait BLUP evaluation within breed

Data Calvings during 2003 or later Parities 1–5 Services 1–7 Age: Heifers 1 to <2.2 years

Cows ≥2 years


U.S. Holstein conception rates

30

40

50

60

70

01 02 03 04 05 06Birth year

Conce

pti

on r

ate

(%

)

-6.0

-3.0

0.0

3.0

6.0 Bre

edin

g v

alu

e (%

)

–––– Heifer CR– – – Heifer BV

–––– Cow CR– – – Cow BV


1.8

2.0

2.2

2.4

2.6

2.8

98 00 02 04 06 08

Breeding year

Serv

ices

(no.)

Holstein Jerse

y

U.S. numbers of services


1.8

2.0

2.2

2.4

2.6

2.8

98 00 02 04 06 08

Breeding year

Serv

ices

(no.)

U.S. Holstein numbers of services




1.8

2.0

2.2

2.4

2.6

2.8

98 00 02 04 06 08

Breeding year

Serv

ices

(no.)

U.S. Jersey numbers of services




Pregnancy rate

Allows herd managers to measure how quickly their cows become pregnant again after having a calf

Defined as percentage of nonpregnant cows that become pregnant during each 21-day period


U.S. pregnancy rates

Jersey–––– PR– – – BV

Holstein–––– PR– – – BV

20

22

24

26

28

30

90 92 94 96 98 00 02 04 06Birth year

Pre

gnancy

rate

(%

)

-2.5

-0.5

1.5

3.5

5.5

7.5 Bre

edin

g v

alu

e (%

)


390

400

410

420

430

98 00 02 04 06 08

Year of interval start

Calv

ing inte

rval (d

ays

)

Holstein

Jersey

U.S. calving intervals


390

400

410

420

430

98 00 02 04 06 08


Calv

ing inte

rval (d

ays

)U.S. Holstein calving intervals




390

400

410

420

430

98 00 02 04 06 08


Calv

ing inte

rval (d

ays

)U.S. Jersey calving intervals




Herd synchronization status

Identified through χ2 analysis with herd size considered

Deviation of observed frequency of 1st inseminations by day of the week from expected equal frequency

Maximum percentage of cows inseminated on a particular day of the week

Status categories Not synchronized Possibly synchronized Probably synchronized Synchronized


Year

Not synchronize

dPossibly

synchronized Probably

synchronized Synchronize

d1998 6516 340 253 61999 6320 423 392 112000 6367 459 647 172001 6545 577 806 562002 6460 570 1001 582003 7111 633 1269 902004 6869 741 1558 1472005 6493 740 1801 2422006 5930 701 1935 3402007 5840 701 2199 4432008 5373 636 2232 549

U.S. herd synchronization (no.)


Year

Not synchronize

dPossibly



d1998 92 5 4 <11999 88 6 6 <12000 85 6 9 <12001 82 7 10 12002 80 7 12 12003 78 7 14 12004 74 8 17 22005 70 8 19 32006 67 8 22 42007 64 8 24 52008 61 7 25 6

U.S. herd synchronization (%)


U.S. herd synchronization (%)

0

25

50

75

100

98 00 02 04 06 08Breeding year

Her

ds

(%)

Not synchronizedPossibly synchronizedProbably synchronizedSynchronized


Year

Not synchronize

dPossibly



d1998 91 5 4 <11999 85 7 7 <12000 80 8 12 <12001 75 9 14 12002 70 10 19 12003 65 9 24 22004 58 10 28 42005 52 9 33 52006 47 9 36 82007 45 9 37 82008 42 9 39 11

U.S. cows by herd synchronization (%)


Synchroni-zation status

Days to 1st

breeding (days)

Concep-tion rate

(%) Services

(no.)

CaIving interval (days)

Not synchronized

88 31 2.4 419

Possibly synchronized

79 29 2.6 413

Probably synchronized

75 29 2.6 412

Synchronized 77 30 2.6 414

U.S. Holstein synchronization and reproduction*

*2008 breedings


U.S. sexed-semen use

PopulationBreeding

yearBreedings

(no.)

Percentage of total breedings

Heifers 2006 5,550 1.42007 41,340 9.52008 81,812 17.8

Cows 2006 1,962 0.12007 7,779 0.22008 16,169 0.4


U.S. sexed-semen conception rates

Conception rate (%)

PopulationBreeding

yearConventiona

l semenSexed semen

Heifers 2006 55 322007 56 422008 55 39

Cows 2006 30 302007 30 262008 31 24


Conclusions

Large decline in U.S. SCC during last decade while herd size and milk yield increased

In spite of less stringent legal standards, U.S. SCC comparable with SCC in other countries (probably because of incentives)

U.S. days to 1st breeding declined partly because of adoption of ovulation synchronization and timed AI


Conclusions (continued)

Units of semen per conception increased somewhat in the U.S.

U.S. pregnancy rates decreased and calving intervals increased for decades but are improving

Use of synchronized breeding has grown in the U.S.


Conclusions (continued)

Use of sexed semen for heifers has grown in the U.S.

Conception rate with sexed semen 20–30% less than with conventional semen in the U.S.


Thank you!

Animal Improvement Programs Laboratory staff – 2010

Documents

Recent trends in mastitis and fertility indicators in the United States and reasons for change