BEEF-PRODUCTION THROUGH THE DAIRY-HERD .2. GROWTH UNTIL 1-YEAR OF AGE OF FEMALE AND MALE HYBRIDS

Growth rate until year of age was analysed in 345 hybrids from crosses of beef bulls (Zebu, Charolais, Santa Gertrudis and 3/4 Limousin 1/4 Criollo) with females 3/4 H 1/4 Z and 5/8 H 3/8 Z through two linear models of fixed effects. The first model included the paternal genotype (4), the maternal genotype (2), sex (2), the birth contemporary group (13), the quadratic regression for calving age and the interaction of the paternal x maternal genotype. The second model considered the genetic group (calf genotype, 8) and also included the interaction of the genetic group x sex. The variables studied were light weight and age on entering the rearing unit and the adjusted weight and the average daily gain (ADG) at 120 and 365 days of age. The interactions of paternal x maternal genotype and genetic group x sex significantly affected the weight and the ADG ant 120 days. The effects of the contemporary group was significant in all measurements studied. The hybrids from Zebu bulls with 3/4 H 1/4 Z females surpassed the remaining crosses by 11.6 kg and 115 g/day for weight and ADG at 120 days, respectively. Results indicated only genetic differences in the rearing stage, which could be associated to management and feeding variations.