FACTORS AFFECTING ACTUAL AND ADJUSTED 90-DAY, 205-DAY AND 365-DAY WEIGHT OF CHAROLAIS CALVES

Body weights on 90 ± 45 days and 205 ± 45 days are body weights used for selection in suckler herds, likewise body weight on 365 ± 45 days are used for selection in performance test according to the Slovenian rules for recording in animal production, which is based on the International Committee for Animal Recording - ICAR. Dilemma which body weights are more suitable: the actual, or the adjusted ones at the recommended age of calves is often present. Comparison between fixed effects on actual and on adjusted 90-day, 205-day and 365-day weights of Charolais calves have been studied. Calves (320) were born from 1995 to 2005 on Educational and Research Animal Husbandry Centre Logatec (Slovenia). Fixed effects of sex, parity, year of birth and birth weight were included in a model for the actual and adjusted body weights. Birth weight was included as linear regression. It has been concluded that parameters affected the actual body weights affected adjusted body weights, too. Birth weight and year of birth influenced 90-day, 205-day and 365-day weight. Parity influenced only 90-day weight, while sex influenced 205-day and 365-day weight. Coefficients of determination for adjusted 90-day weight (0.38), 205-day weight (0.38) and 365-day weight (0.73) were higher than for actual body weights (0.20, 0.30 and 0.60, respectively)