Does growth path influence beef fatty acid composition?

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40 young Alentejana bulls were either fed hay and concentrates ad libitum (CG group) until 18 months of age or subject to food restriction from 9 to 15 months of ...

A.S.H. Costa2, P. Costa2*, S. P. Alves2, C. P. M. Alfaia2, J. A. Simões1, Paula Lopes2, J. F. Hocquette3, C. R. Calkins4, and R. J. B. Bessa1,2

1L-INIAV

Santarém, Instituto Nacional dos Recursos Biológicos, Quinta da Fonte Boa, 2005-048 Vale de Santarém - Faculdade de Medicina Veterinária, Universida de Lisboa, Avenida da Universidade Técnica, Pólo Universitário do Alto da Ajuda, 1300-477 Lisboa, Portugal. UR 1213, Unité de Recherches sur les Herbivores (URH), Theix, F-63122 Saint-Genés Champanelle, France. 4University of Nebraska, Department of Animal Science, Lincoln, Nebraska, USA1A contribution of the University of Nebraska Agricultural Research Division, Lincoln, NE 68583. 2CIISA

3INRA,

Conclusions

Aims Take advantage of the recent progress in genomics to acquire a better knowledge of the biochemical traits and the genes dictating bovine

meat quality.

To investigate the effects of the growth path on gene expression and beef

fatty acid composition.

Background

The results from the present study show that compensatory growth impacts on fatty acid deposition through enhanced fatty acid synthesis and elongation. Lipid

metabolism is affected by growth path to

a transcriptional and molecular level, with beneficial effects on the nutritional quality of meat obtained.

Results and discussion

Discontinuous growth doesn’t impact negatively on IMF deposition

An alternative to these intensive finishing systems is the traditional Mediterranean system in which young bulls are feed-restricted in summer when pasture availability is scarce, and are fed pasture ad libitum during the spring, when grass availability and quality increase [1]. This strategy take advantage of the compensatory growth. In spite of the recent advances in transcriptomics, there is still a shortage of gene expression studies addressing the adaptations in skeletal muscle of cattle in response to compensatory growth, particularly regarding lipid metabolism.

IMF (g/100 g meat)

2,5

Similar levels of intramuscular fat (IMF) were observed in the meats of continuous (CG) and discontinuous growth (DG) groups

2,0 1,5 1,0 0,5 0,0

CG

DG

Growth path impacts on meat fatty acid composition 50

**

45

Feed restricted bulls deposit lower proportions of saturated (SFA) and branched chain fatty acids (BCFA)

Fatty acid partial sums (mol%)

Experimental design

40 young Alentejana bulls were either fed hay and concentrates ad libitum (CG group) until 18 months of age or subject to food restriction from 9 to 15 months of age (only hay was provided), and fed hay and concentrates ad libitum until 24 months of age (DG group).

40 35 30 25

CG DG

Increased 18:1-t10

20 15 10

**

5 0

SFA

Alentejana bulls (n=40)

cisMUFA

TFA

* BCFA

PUFA

n-3 PUFA

Compensatory growth enhances fatty acid desaturation

Material and methods Meat samples were lyophilised to constant weight. The IMF in lyophilised samples was extracted, converted to fatty acid methyl esters and analysed as described by Jerónimo et al. [2]. A new cDNA chip was developed by the INRA to access the expression of more than 3000 genes or bovine EST sequences related to growth, carcass fatness and beef quality including connective tissues, proteolytic activity, metabolic enzymes. Total RNA was amplified and labelled with Cyanine 3 using Agilent’s Low RNA Input Linear Amplification Kit, PLUS, One-Color (Agilent Technologies) following the detailed protocol described by Hocquette et al. [3]. Fatty acid composition Gas Cromatography

Gene expression

microarray

80

Acknowledgements Abattoir staff for their cooperation in carcass collection data and meat sampling  Unidade de Produção Animal, Instituto Nacional de Investigação Agrária e Veterinária (INIAV)staff for assistance in animal management  PTDC/CVT/111744/2009 grant  individual fellowships SFRH/BD/2009/61068 and SFRH/BPD/2008/46135

60

***

50 40 30 20 0

*

*

10 ID14

ID16

ID17

ID18

CG DG

n-6 PUFA

Significance level: *, P

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