The evaluation of the effect of imported semen based on different selection indices on the phenotypic changes of production traits of Holstein cattle in various climates of Iran

The aim of the present study was to investigate the effect of imported semen under different selection indices on phenotypic changes of production traits in Holstein cattle population in various climates of Iran. In the present research, records of first lactation on milk yield, fat and protein percentage of 269786, 216850 and 270566 Holstein cattle derived from imported semen under different selection indices in cold, semi-cold, moderate and warm climates, were used. The data were collected by the Center of Breeding and Improvement of Livestock Production during 1993 to 2017. The data were analyzed using the General Linear Model (GLM) software SAS 9.2. In cold, semi-cold, moderate and warm climates, the means of milk yield (kg) in the progenies of imported semen were estimated, 9597.92, 9654.46, 9718.34 and 8985.37, the means of fat percentage were estimated, 3.13, 3.07, 3.08 and 3.15 percent, and the means of protein percentage were estimated 3.10, 3.25, 3.14, and 3.16 percent, respectively. In the present study, the highest least square means of the phenotypic value of Holstein cattle derived from imported semen based on different selection indices in cold, semi-cold, moderate and warm climates were according to countries of France 2001-2011, Italy 1993- 2001, Netherlands 2001-2006, France 2001-2011 for milk yield, Netherlands 1999-2000, United States 1987-1988, United States 1992-1993, and Canada 1998-2000 for fat percentage and Canada 1991-1992, France 2012-2013, Sweden 2008-2012 and Germany 2002 -2007 for protein percentage, respectively.