2008 ADSA-ASAS Joint Annual Meeting

Indianapolis, July 7-11

Genetic Parameters of Saturated and Monounsaturated Fatty Acids

Estimated by Test-Day Model in Walloon Dairy Cattle

H. Soyeurt1, C. Bastin1, P. Dardenne2, F. Dehareng2, and N. Gengler1,3

1 Gembloux Agricultural University, Animal Science Unit, Belgium2 Walloon Agricultural Research Centre, Quality Department, Belgium

3 National Fund for Scientific Research, Belgium

Introduction

Interest for human health Milk fatty acid composition:

Saturated (SAT): 70% Monounsaturated (MONO): 25% Polyunsaturated : 5%

Introduction

Interest for human health Milk fatty acid composition:

Saturated (SAT): 70% (vs. 30%) Monounsaturated (MONO): 25% (vs. 60%) Polyunsaturated : 5% (vs. 10%)

Introduction

Interest for human health Milk fatty acid composition:

Saturated (SAT): 70% (vs. 30%) Monounsaturated (MONO): 25% (vs. 60%) Polyunsaturated : 5% (vs. 10%)

Modifying the milk fatty acid profile

General Objective

Sources of variation: Feeding Genetic:

• Previous studies: Moderate heritability estimates• Constant genetic parameters throughout the

lactation?

Aim of this study: Estimate the genetic parameters for SAT and

MONO in bovine milk using multi-trait random regression test-day models

Materials & Methods

Data set: 4 < DIM < 366 100,799 TD records (1991-2007)

• Including 4,666 spectra (March 2005 – July 2007)

11,626 primiparous Holstein cows 18,573 animals in the pedigree

Materials & Methods

Estimation of SAT and MONO contents New PLS calibration equations 114 milk samples in the calibration set

Indicator of butter hardness = SAT:UNSAT

g/dL of milk R²cv RPD

SAT 0.97 5.78

MONO 0.93 3.65

Studied traits

10

20

30

40

50

60

70

80

90

100

10 20 30 40 50 60 70 80 90 100

Chromatographic values

MIR

val

ues

pp

p

Saturated (g/dl of milk)

Monounsaturated (g/dl of milk)

Validation on 14 milk samples

R=0.92

R=0.92

R= correlation between reference and MIR data

Studied traits

  N Mean SD

Milk (kg/day) 100,799 22.54 6.13

Fat (g/100g of milk) 100,799 4.05 0.68

Protein (g/100g of milk) 100,799 3.32 0.34

SAT (g/100g of milk) 4,666 2.63 0.54

MONO (g/100g of milk) 4,666 1.08 0.26

SAT (g/100g of fat) 4,666 66.26 6.15

MONO (g/100g of fat) 4,666 27.55 4.80

SAT:UNSAT 4,666 2.06 0.55

Studied traits

  N Mean SD

Milk (kg/day) 100,799 22.54 6.13

Fat (g/100g of milk) 100,799 4.05 0.68

Protein (g/100g of milk) 100,799 3.32 0.34

SAT (g/100g of milk) 4,666 2.63 0.54

MONO (g/100g of milk) 4,666 1.08 0.26

SAT (g/100g of fat) 4,666 66.26 6.15

MONO (g/100g of fat) 4,666 27.55 4.80

SAT:UNSAT 4,666 2.06 0.55

Studied traits

  N Mean SD

Milk (kg/day) 100,799 22.54 6.13

Fat (g/100g of milk) 100,799 4.05 0.68

Protein (g/100g of milk) 100,799 3.32 0.34

SAT (g/100g of milk) 4,666 2.63 0.54

MONO (g/100g of milk) 4,666 1.08 0.26

SAT (g/100g of fat) 4,666 66.26 6.15

MONO (g/100g of fat) 4,666 27.55 4.80

SAT:UNSAT 4,666 2.06 0.55

Materials & Methods

Models: Fixed effects:

• Herd x date of test• Class of 15 days in milk• Class of age

Random effects:• Herd x year of calving• Permanent environment• Additive genetic effect• Residuals

Materials & Methods

Models: Fixed effects:

• Herd x date of test• Class of 15 days in milk• Class of age

Random effects:• Herd x year of calving• Permanent environment• Additive genetic effect• Residuals

Second order Legendre Polynomials

Results: Lactation Effect

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

0 40 80 120 160 200 240 280 320 360

Days in milk

Est

imat

es

ppp

SAT:UNSAT MONO (g/100 g of milk)

SAT (g/100 g of milk) Fat (g/100 g of milk)

Results: Season Effect

0

0.5

1

1.5

2

2.5

3

3.5

1 2 3 4 5 6 7 8 9 10 11 12

Month of test day

Est

imat

es

ppp

SAT:UNSAT MONO (g/100g of milk)

SAT (g/100g of milk)

0

0.1

0.2

0.3

0.4

0.5

0.6

1 3 5 7 9 11 13 15 17 19 21 23 25

Class of 15 days in milk

He

rita

bil

ity

Fat (g/100g of milk) SAT (g/100g of milk) MONO (g/100g of milk) SAT:UNSAT

Results: Heritability (milk)

0

0.1

0.2

0.3

0.4

0.5

0.6

1 3 5 7 9 11 13 15 17 19 21 23 25

Class of 15 days in milk

He

rita

bil

ity

Fat (g/100g of milk) SAT (g/100g of milk) MONO (g/100g of milk) SAT:UNSAT

Results: Heritability (milk)

0

0.1

0.2

0.3

0.4

0.5

0.6

1 3 5 7 9 11 13 15 17 19 21 23 25

Class of 15 days in milk

He

rita

bil

ity

Fat (g/100g of milk) SAT (g/100g of milk) MONO (g/100g of milk) SAT:UNSAT

Results: Heritability (milk)

Results: Heritability (fat)

0

0.1

0.2

0.3

0.4

0.5

5 35 65 95 125 155 185 215 245 275 305 335 365

Class of 15 days in milk

Her

itab

ility

SAT (g/100g of fat)MONO (g/100 g of fat)

0

2

4

6

8

10

12

14

16

0 50 100 150 200 250 300 350

Days in milk

Va

ria

nc

es (

g²/

100

g o

f fa

t²)

Herd x calving date Permanent Environment Genetic

Results: Variances (%SAT)

Mobilization of lipids from adipose tissue ???

Results

-1

-0.5

0

0.5

1

5 80 155 230 305

Days in milk

Gen

etic

corr

elat

ion

ppp

Milk (kg/day) - SAT (g/100g of milk) Fat - SAT (g/100g of milk) Protein - SAT (g/100g of milk)

SAT - MONO (g/100g of milk) SAT (g/100g of milk) - SAT:UNSAT

Conclusion

Results confirm the genetic variability of fatty acids

Genetic parameters of fatty acids change throughout the lactation: Highest heritability and additive genetic variance at

the beginning and at the end of the lactation Correlations between SAT and MONO change within

the lactation

Partly influenced by the fatty acid production??

Thank you for your attention

soyeurt.h@fsagx.ac.be

Acknowledgments

FNRS grants:

2.4507.02

F.4552.05

2.4623.08

Walloon Breeding Association

Milk Committee of Battice