Estimation of heritability and genetic correlations for the major fatty acids in bovine milk.

The current cattle selection program for dairy cattle in the Walloon region of Belgium does not consider the relative content of the different fatty acids (FA) in milk. However, interest by the local dairy industry in differentiated milk products is increasing. Therefore, farmers may be interested in selecting their animals based on the fat composition. The aim of this study was to evaluate the feasibility of genetic selection to improve the nutritional quality of bovine milk fat. The heritabilities and correlations among milk yield, fat, protein, and major FA contents in milk were estimated. Heritabilities for FA in milk and fat ranged from 5 to 38%. The genetic correlations estimated among FA reflected the common origin of several groups of FA. Given these results, an index including FA contents with the similar metabolic process of production in the mammary gland could be used, for example, to increase the monounsaturated and conjugated fatty acids in milk. Moreover, the genetic correlations between the percentage of fat and the content of C14:0, C12:0, C16:0, and C18:0 in fat were -0.06, 0.55, 0.60, and 0.84, respectively. This result demonstrates that an increase in fat content is not directly correlated with undesirable changes in FA profile in milk for human health. Based on the obtained genetic parameters, a future selection program to improve the FA composition of milk fat could be initiated.

[1]  P. Garnsworthy,et al.  Seasonal variation in milk conjugated linoleic acid and Δ9-desaturase activity in dairy cows , 2003 .

[2]  R. Veerkamp,et al.  Covariance functions across herd production levels for test day records on milk, fat, and protein yields. , 1998, Journal of dairy science.

[3]  D. Barbano,et al.  Feed and animal factors influencing milk fat composition. , 1993, Journal of dairy science.

[4]  E. Mäntysaari,et al.  Multiple trait reduced rank random regression test-day model for production traits , 1999 .

[5]  G. Wiggans,et al.  Within-herd effects of age at test day and lactation stage on test-day yields. , 2003, Journal of dairy science.

[6]  D. Beitz,et al.  Associations among individual proteins and fatty acids in bovine milk as determined by correlations and factor analyses , 1999, Journal of Dairy Research.

[7]  C. J. Wilcox,et al.  Bivariate animal model estimates of genetic, phenotypic, and environmental correlations for production, reproduction, and somatic cells in Jerseys. , 2000, Journal of dairy science.

[8]  M. Doreau,et al.  Ruminant milk fat plasticity: nutritional control of saturated, polyunsaturated, trans and conjugated fatty acids , 2000 .

[9]  R. Grummer,et al.  Effect of feed on the composition of milk fat. , 1991, Journal of dairy science.

[10]  N Gengler,et al.  Estimated heterogeneity of phenotypic variance of test-day yield with a structural variance model. , 2004, Journal of dairy science.

[11]  R. A. Edwards,et al.  A note on the genetic variation in the fatty acid composition of cow milk , 1973 .

[12]  M. Doreau,et al.  Contrôle de la qualité nutritionnelle des matières grasses du lait par l’alimentation des vaches laitières : acides gras trans, polyinsaturés, acide linoléique conjugué , 2001 .

[13]  P. Parodi.  Conjugated linoleic acid and other anticarcinogenic agents of bovine milk fat. , 1999, Journal of dairy science.

[14]  H Soyeurt,et al.  Variation in fatty acid contents of milk and milk fat within and across breeds. , 2006, Journal of dairy science.

[15]  J. L. Querler,et al.  Analyse des acides gras du beurre par chromatographie en phase gazeuse couplee avec la spectrometrie de masse. Etude preliminaire. , 1988 .

[16]  U Emanuelson,et al.  A simple method for weighted bending of genetic (co)variance matrices. , 2003, Journal of dairy science.

[17]  A. Simopoulos.  Importance of the ratio of omega-6/omega-3 essential fatty acids: evolutionary aspects. , 2003, World review of nutrition and dietetics.

[18]  P. Dardenne,et al.  Estimating fatty acid content in cow milk using mid-infrared spectrometry. , 2006, Journal of dairy science.

[19]  J. Manson,et al.  Dietary saturated fats and their food sources in relation to the risk of coronary heart disease in women. , 1999, The American journal of clinical nutrition.

[20]  M. Noakes,et al.  Modifying the fatty acid profile of dairy products through feedlot technology lowers plasma cholesterol of humans consuming the products. , 1996, The American journal of clinical nutrition.

[21]  O. Syrstad,et al.  Sources of variation in composition of milk fat , 1982, Annales de génétique et de sélection animale.

[22]  V. Ducrocq,et al.  Estimation of genetic parameters for test day records of dairy traits in the first three lactations , 2005, Genetics Selection Evolution.

[23]  Robert G. Jensen,et al.  Handbook of milk composition , 1995 .

[24]  H. Hammami,et al.  Multivariate animal model estimates of genetic, environmental and phenotypic correlations for early lactation milk yield and composition in Tunisian Holstein-Friesians , 2004 .