Comparison of preweaning growth traits of six beef cattle breeds in the Czech Republic

In the years 1992 to 1998 six beef cattle breeds (Angus, Czech Pied, Herefo rd, Charolais, Limousin and Piemontese) were tested and the data on the fol lowing traits of calves were analyzed: birth weight, 120-day and 210-day we ight and average daily gains (birth - 120 days, birth - 210 days and 120 - 210 days). The comparison of breeds and traits was based on the overall mea ns (mu) and phenotypic standard deviations (sigma (p)). Both phenotypic par ameters were obtained in the preceding analyses of these breeds by the gene ralized least squares method. The traits were analysed with respect to year of birth (1992-1998), herd, sex (male, female), calf number (single, twin) , parity and sire. The phenotypic standard deviations of traits were transf ormed into genetic standard deviations (sigma (o)) by multiplication by the square root of the corresponding heritabilities. Genetic standard deviatio ns were used to compare the genetic variability of breeds. The Hereford cat tle showed the lowest overall means and a very low phenotypic and genetic v ariability in all traits. The variability was also very low in the Limousin for all growth traits. High overall means for all growth traits were recor ded in the Charolais. The Piemontese exceeded the Charolais slightly in bir th weight and the Czech Pied cattle showed a higher daily gain from 120 to 210 days than the Charolais. The Charolais had high standard deviations (ph enotypic and genetic) with respect to all preweaning growth traits. Similar high standard deviations were also recorded in the Piemontese breed for we ight at birth, 120 days and for the average daily gains from birth to 120 d ays and in the period of 120-210 days. In the 120-day and 210-day weights, and daily gains (birth - 120 days, birth - 210 days) a similar ranking of b reeds was found. For the majority of traits the Piemontese breed showed ave rage values. The other breeds (with the exception of Angus for the 120 day weight) were located above the average of the extremes. Theoretical frequen cy curves based on the normal distribution and the genetic standard deviati ons (mu +/- 3 sigma (o)) were used for comparing the weights from birth to weaning for three breeds representing the average and both extremes. Freque ncy curves for birth weight of Hereford and Charolais do not overlap, the A ngus breed is in the middle of both these breeds. For the weights at 120 an d 210 days differences between frequency curves are much less pronounced an d show stronger overlapping between Hereford, Piemontese and Charolais bree ds.