j. b. cole 1, p. d. miller 2, and h. d. norman 1 1 animal improvement programs laboratory...

J. B. ColeJ. B. Cole11, P. D. Miller, P. D. Miller22, and H. D. Norman, and H. D. Norman11

1Animal Improvement Programs Laboratory Agricultural Research Service, USDA, Beltsville, MD2Department of Dairy Science University of Wisconsin-Madison, Madison, WI

2004

Genetic Improvement of Dairy Cattle Health

Genetic Improvement of Dairy Cattle Health John B. Cole2004

OverviewOverview

• Response to selection using field-recorded traits is efficient and well-documented.

• Herd owners are interested in healthy, longer-lived cows.

• Genetic variability exists for health traits of economic interest.


OverviewOverview

• Statistical and computational tools for genetic evaluation exist.

• Data processing routines can be developed.

• However, data needed for routine evaluations are limited.


Why select for improved health?Why select for improved health?

• Longer-lived (more profitable) cows.

• Decreased cost of production.

• Reduced herd turnover.

• Improved animal welfare.

• Genetic gains are cumulative!


Desirable Properties of Health TraitsDesirable Properties of Health Traits

• Reasonably large genetic variability or heritability.

• Significant economic value.

• Reasonable cost of measurement and recording.

• Consistent methods for measurement and recording.

(Shook, 1989)


ChallengesChallenges

• Low heritabilities for some traits.

• Unfavorable correlations with milk, fat, and protein yield.

• Affected animals have a low frequency of occurrence.

• Diagnoses may be uncertain.

• Data are not collected in a national database.


Heritabilities and Correlations of Heritabilities and Correlations of Composite Health TraitsComposite Health Traits

(Lyons, Freeman, and Kuck, 1991)

Reproduct. Mammary Digestive Locomotive Respiratory

Reproduct. 0.02±0.04 -0.11* 0.38 0.02 -0.23*

Mammary 0.12±0.06 0.52 0.84 0.34

Digestive 0.21±0.08 0.87 0.76

Locomotive 0.16±0.07 0.74

Respiratory 0.02±0.04

* Negative genetic correlations reflect undesirable relationship.


Genetic Correlations Between Genetic Correlations Between Composite Health and Yield TraitsComposite Health and Yield Traits

(Lyons, Freeman, and Kuck, 1991)

Milk Yield Fat YieldReproductive -0.27* -0.25*Mammary 0.18 -0.06*Digestive 0.44 -0.06*Locomotive 0.48 0.45* Negative genetic correlations reflect undesirable relationship.


Genetic Tools Currently AvailableGenetic Tools Currently Available

• Calving Ease: Easier calving, less dystocia, fewer stillbirths (h2=0.022).

• Daughter Pregnancy Rate: Improved female fertility (h2=0.040).

• Productive Life: Longer working life (h2=0.085).

• Somatic Cell Score: Improved resistance to mastitis (h2=0.100).


Holstein Daughter Pregnancy Rate (%)

-2

-1

0

1

2

3

4

5

6

Cow BVSire BV

Holstein Birth Year

Bre

edin

g V

alue


Holstein Productive Life (mos)

-7

-6

-5

-4

-3

-2

-1

0

1

2

Cow BVSire BV

Holstein Birth Year

Bre

edin

g V

alue


Format 6Format 6

• The USDA Animal Improvement Programs Laboratory has drafted a data exchange format to collect health data.

• It includes standard health codes.

• The objective is to collect data for research.

• The goal is to facilitate selection for healthier cows.


Format 6 RecordsFormat 6 Records

• Format 6 records include Animal and herd identification Up to 20 health event segments

• Cow records begin with a calving and end with disposal or the next calving.

• Heifer records begin at birth and end at first calving.


Health Event SegmentHealth Event Segment

• Health event code

• Health event date

• Health event detail (optional)


Standard Health Event CodesStandard Health Event Codes

• Currently, no health event codes are used uniformly in dairy records systems.

• Standard codes have been developed based on frequency of occurrence in field data and consultation with veterinarians.


Health Event CodesHealth Event CodesCystic ovary

Diarrhea/scours

Digestive problem/off feed

Displaced abomasum

Downer cow

Dystocia

Johne’s disease (clinical)

Ketosis/acetonemia

Lameness

Mastitis (clinical)

Metritis

Milk fever/hypocalcemia

Nervous system problem

Other reproductive problem

Respiratory problem

Retained placenta

Stillbirth

Teat injury

Udder edema


Most Frequent Health Events in Most Frequent Health Events in DRMS DataDRMS Data

Frequency Percent of Events*

Mastitis 496,531 19.27

Lameness 128,869 5.00

Metritis 126,269 4.90

Cystic ovary 81,936 3.18

Retained placenta 57,691 2.24

Digestive problem 47,156 1.83

Respiratory problem 39,918 1.55

Ketosis 25,541 0.99

Displaced abomasum 21,908 0.85*Frequency and percent based on 2,577,004 health event observations.


Management EventsManagement Events

• Three management traits are also in Format 6 Body condition score Milking speed Temperament

• The format can accommodate new traits e.g. Locomotion score


Optional Health Event DetailOptional Health Event Detail

• Details of problems of high economic impact (e.g. clinical mastitis) There is one mastitis event code. Organism and quarter may be

reported.

• Other codes may also use this field Dystocia: scores of 1 to 5. BCS: scores of 1.00 to 5.00.


Research NeedsResearch Needs

• Data quality edits

• Individual versus composite traits

• Environmental factors affecting records

• Relationships among traits

• Variance components estimation

• Genetic evaluation models


SummarySummary

• Format 6 provides the framework for a national health database.

• Selection for improved health is possible and desirable.

• Selection complements advances in management and veterinary care.

j. b. cole 1, p. d. miller 2, and h. d. norman 1 1 animal improvement programs laboratory...

Documents

health data

improved health

genetic tools

genetic evaluation

genetic gains

health traits of economic

negative genetic correlations

large genetic variability