Milk production

Effect of casein genes - beta-LGB, DGAT1, GH, and LHR - on milk production and milk composition traits in crossbred Holsteins

A. Molee, Poompramun, C., and Mernkrathoke, P., Effect of casein genes - beta-LGB, DGAT1, GH, and LHR - on milk production and milk composition traits in crossbred Holsteins, vol. 14, pp. 2561-2571, 2015.

The objectives of this study were to determine the effects of a single gene and composite genotype of the casein gene family, including the beta-lactoglobulin gene (beta-LGB), acyl-CoA: diacylglycerol acyltransferase 1 gene (DGAT1), growth hormone gene (GH), and luteinizing hormone receptor gene (LHR) on milk yield, milk composition, the percentage of fat, protein, solids-not-fat, and total solid in crossbred Holsteins. A total of 231 crossbred Holstein cows were examined for the study.

Random regression models using different functions to model milk flow in dairy cows

M. M. M. Laureano, Bignardi, A. B., L. Faro, E., Cardoso, V. L., Tonhati, H., and Albuquerque, L. G., Random regression models using different functions to model milk flow in dairy cows, vol. 13, pp. 7528-7541, 2014.

We analyzed 75,555 test-day milk flow records from 2175 primiparous Holstein cows that calved between 1997 and 2005. Milk flow was obtained by dividing the mean milk yield (kg) of the 3 daily milking by the total milking time (min) and was expressed as kg/min. Milk flow was grouped into 43 weekly classes. The analyses were performed using a single-trait Random Regression Models that included direct additive genetic, permanent environmental, and residual random effects.

Georeferenced evaluation of genetic breeding value patterns in Brazilian Holstein cattle

N. S. Costa, Hermuche, P., Cobuci, J. A., Paiva, S. R., Guimaraes, R. F., Carvalho, Jr., O. A., Gomes, R. A. T., Costa, C. N., and McManus, C. M., Georeferenced evaluation of genetic breeding value patterns in Brazilian Holstein cattle, vol. 13, pp. 9806-9816, 2014.

The aim of this study was to analyze the relationship between environmental and genetic values for milk production and type traits in Holstein cattle in Brazil. The genetic value of 65,383 animals for milk production and 53,626 for type classification were available. Socioeconomic and environmental data were obtained from the Brazilian Institute of Geography and Statistics, the Food and Agriculture Organization of the United Nations, the National Aeronautics and Space Administration, and the National Institute of Meteorology.

Comparison of factor-analytic and reduced rank models for test-day milk yield in Gyr dairy cattle (Bos indicus)

R. J. Pereira, Ayres, D. R., L. Faro, E., Verneque, R. S., Filho, A. E. Vercesi, and Albuquerque, L. G., Comparison of factor-analytic and reduced rank models for test-day milk yield in Gyr dairy cattle (Bos indicus), vol. 12, pp. 4036-4045, 2013.

We analyzed 46,161 monthly test-day records of milk production from 7453 first lactations of crossbred dairy Gyr (Bos indicus) x Holstein cows. The following seven models were compared: standard multivariate model (M10), three reduced rank models fitting the first 2, 3, or 4 genetic principal components, and three models considering a 2-, 3-, or 4-factor structure for the genetic covariance matrix. Full rank residual covariance matrices were considered for all models.

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