Linear and curvilinear effects of inbreeding on production traits for walloon Holstein cows

in Journal of Dairy Science (2007), 90(1), 465-471

The nonlinear effects of inbreeding were studied by comparing linear and curvilinear regression models of phenotypic performances on inbreeding coefficients for production traits (milk, fat, and protein ... [more ▼]

The nonlinear effects of inbreeding were studied by comparing linear and curvilinear regression models of phenotypic performances on inbreeding coefficients for production traits (milk, fat, and protein yields) of Holstein cows in their first lactation. Three different regression models (linear, quadratic, and cubic) were introduced separately into a single-trait, single-lactation, random regression test-day model. The significance of the different regression coefficients was studied based on a t-test after estimation of error variances and covariances associated with the different regression coefficients. All of the tested regression coefficients were significantly different from 0. The traditional regression coefficients of milk, fat, and protein yields on inbreeding were, respectively, -22.10, -1.10, and -0.72 kg for Holstein cows in their first lactation. However, the estimates of 305-d production losses for various classes of animals based on inbreeding coefficients showed that the effect of inbreeding was not a linear function of the percentage of inbreeding. The 305-d milk yield loss profiles attributable to inbreeding, obtained by the various regression models, were different. However, for inbreeding coefficients between 0 and 10%, these differences were small. [less ▲]

Variation of lactoferrin content predicted by mid-infrared spectrometry (MIR)

in Book of Abstracts of the 58th Annual Meeting of the European Association for Animal Production (2007)

Principal components approach for estimating heritability of mid-infrared spectrum in bovine milk

in Journal of Dairy Science (2007)

Within and across breeds differences in fatty acids profiles of milk and milk fat in dairy cows

Poster (2006, August)

Potential estimation of fatty acid content in cow milk by mid-infrared spectrometry

Conference (2006, June)

Estimation of fatty acid profile in cow milk by mid-infrared spectrometry

Poster (2006, April 03)

Use of Interbull traits as indicators for only locally evaluated traits as milk quality traits

in Interbull Bulletin (2006), 35

Variation in fatty acid contents of milk and milk fat within and across breeds

in Journal of Dairy Science (2006), 89(12), 4858-4865

The aim of this research was to study the potential for selection of cows with a higher nutritional quality of milk fat by studying the differences in fatty acid profiles within and across the following ... [more ▼]

The aim of this research was to study the potential for selection of cows with a higher nutritional quality of milk fat by studying the differences in fatty acid profiles within and across the following breeds: Dual Purpose Belgian Blue, Holstein-Friesian, Jersey, Montbeliarde, and non-Holstein Meuse-Rhine-Yssel type Red and White. Six hundred milk samples from 275 animals were taken from 7 herds. Several types of fatty acids in milk and milk fat were quantified using midinfrared spectrometry and previously obtained calibration equations. Statistical analyses were made using a mixed linear model with a random animal effect. The variance components were estimated by using REML. Results showed breed differences for the fatty acid profile. The repeatability estimate obtained in the present study may suggest the existence of moderate additive genetic variance for the fatty acid profile within each breed. Results also indicated variation for each analyzed milk component in the whole cow population studied. Genetic improvement of the nutritional quality of milk fat based on fatty acid profiles might be possible, and further research and development are warranted. [less ▲]

Qualité nutritionnelle du lait - Etude de la variabilité intra- et inter-races du profil en acides gras du lait

in Le Bulletin (2006), (2), 8-10

Estimation of fatty acid profile in cow milk by mid-infrared spectrometry

in European seminar on infrared spectroscopy (2006)