Influence of the calving season of Girolando calves on development in the initial phase after birth, reproductive performance, and productive performance

Abstract

Raising heifers is one of the most important activities in dairy farming because heifers
eventually replace the herd. This study was performed to evaluate how the calf’s birth season affects its
early development and its reproductive and productive performance. The experiment was conducted
at the Glória Experimental Farm of the Federal University of Uberlândia, Minas Gerais, Brazil. In total,
74 female calves born from January 2018 to March 2020 were evaluated from the first day of life to
the end of their first lactation. The animals were classified according to their season of birth: spring/
summer (October–March) or fall/winter (April–September). During the initial phase of life, the animals’
weights were assessed on days 0, 30, and 60 after birth and at weaning. The rectal temperature, fecal
score, feed intake, and animal behavior were recorded daily. In the mature phase of life, the dates of
conception and calving were evaluated, and milk production during the first lactation was monitored.
The following variables were analyzed according to season of birth: weight gain and occurrence of
diseases during the initial phase, percentage of heifers that calved, age at first calving, and average
milk production during the first lactation. Continuous variables were analyzed by analysis of variance,
and binomial variables were analyzed by logistic regression using the Minitab software program.
Calves born in fall/winter had a higher weight at 30 days; however, this difference was compensated
for during the initial phase and did not interfere with reproductive and productive performance.