Effect of genetic group of bovine crossbreeding Holsstein Gyr on the females weight gain at different ages
Keywords:
adaptability, crossbreeding, gir, growing, holsteinAbstract
The objective of this work was to evaluate the influence of the genetic group of crossbreeding from birth up to 330 kg of liveweight on the average daily gain (ADG). The herd was constituted by crossbreeding Gyr Holsteins animals and the crossing system was rotational crossings with repetitions of Holstein sires. The data used was collected in the herd during 6 years. Analyses of variance were carried out by the least square method, with models wich included the effects of year, seasons of calving, genetic group and their interactions. Females were assigned to genetic groups according to percentage of Holstein in their breed composition: G1 (53 to 62.5), G2 (62.5 to 81) and G3 (84 to 94). Animals were weighted monthly and the ADGs were calculated from birth to 2 months, from 2 to 6 months, from 6 to 12 months and from 12 months to 330kg of liveweight. There were no effects of genetic group (P > .05) on the ADG from birth to 2 and from 2 to 6 months of age. There was no interaction between the genetic group and season of birth. Considering animals from 6 to 12 months of age, the genetic group by season interaction was significant (P < .05): animals G1 born from October to March had higher daily gain than animals born from March to September. Considering animals from 12 months of age to 330kg of liveweight, there was significant difference between ADG within different genetic groups and there was interaction effect between year of birth and genetic group. However, there was no effect or interaction of birth season. The ADGs of heifers G3 were lower than of heifers G1.
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