Within and Across Breeds Differences in Fatty
Acids Profiles of Milk and Milk Fat in Dairy Cows
H. Soyeurt1,2, P. Dardenne3, P. Mayeres1,4, C. Croquet1,5, S. Vanderick1, C. Bertozzi4
and N. Gengler1,5
1 Gembloux Agricultural University, Passage des Déportés 2, B-5030 Gembloux, Belgium,
E-mail: soyeurt.h@fsagx.ac.be
2 F.R.I.A., B-1000 Brussels, Belgium
3 Walloon Agricultural Research Centre, Quality Department, B-5030 Gembloux, Belgium 4 Walloon Breeders Association, B-5530 Ciney, Belgium
5National Fund for Scientific Research, B-1000 Brussels, Belgium
Objective
Improving the nutritional quality of milk fat by animal
selection ?
The variability within and across breeds in fatty acid (FA) profile of
cow milk was studied with the
predicted concentrations of FA by Mid-Infrared (MIR) Spectrometry
for each milk sample and with mixed model theory.
Methods
• After calibration, the FA contents of cow milk was predicted by MIR Spectrometry.
• From April to June 2005, 600 milk samples were analysed from 275 cows derived to 6 breeds (Dual
Purpose Belgian Blue (DPB), DPB
Holstein-Friesian (HOL), Jersey HOL
(JER), Montbeliarde (JER MON) and MON
Red and White (RED).RED
• Single trait mixed model :Fixed
effect: herd*test date, number of lactation, stage of lactation and
regressions on breed composition effects as a lot of animals were
crossbred, when FA contents in
fat were analyzed a regression on % of milk fat was added
• The variation within and across breeds in the activity of delta-9
desaturase was also studied with the same mixed model.
Conclusions
• High variability across breeds choice of breed modified the FA profile
• High repeatability potentially high heritability for each FA
Suggest the possibility of
genetic improvement
1
1
2
2
4
4
Results
Fatty acids concentrations in milk
-1.00 -0.50 0.00 0.50 1.00 1.50 2.00 st an da rd d ev ia ti on u n it s DPB RED MON JER
Fatty acids concentrations in milk fat
-0.40 -0.20 0.00 0.20 0.40 0.60 0.80 1.00 1.20 SAT C12:0 C14:0 st an da rd d ev ia ti on u n it s
Activity of delta-9 desaturase
-0.80 -0.60 -0.40 -0.20 0.00 0.20 0.40 C18:1/C18:0 C16:1/C16:0 C14:1/C14:0 st an da rd d ev ia ti on u ni ts Figure 1 : Differences in fatty acids composition in milk (standardized units) compared to Holsteins. Figure 2: Differences in fatty acids profiles in milk fat (standardized units) compared to Holsteins. Figure 3: Differences in activity of delta-9 desaturase (standardized units) compared to Holsteins.
DPB : lowest fat (MG) but C18:1 and C18:2
9-cis, 12-cis
not the lowest concentrations (Figure 1) unsaturated FA proportion in fat might be high In fact, the fat of DPB contained the lowest proportion in saturated FA (SAT) (Figure 2) These observations might be explained by the higher activity of delta-9 desaturase for this breed (Figure 3).JER : very high difference in monounsaturated fatty acids (MONO)
not lowest delta-9 desaturase activity.
RED and MON : high proportion of SAT low delta-9 activity.
To estimate the differences within breed, the repeatability for each studied traits were estimated and the obtained results were high with values between 43 and 61 %. Future studies should show if this is also an indication for reasonable high heritabilities.
