Potential risk of thermal stress for Bradford bulls in Brazilian tropical and subtropical regions
Silvio Renato Oliveira Menegassi
Carolina Gabriela Becker Berlitz
Marcela Kuczynski da Rocha
Gabriel Ribas Pereira
Celso Koetz Jr
Júlio Otávio Jardim Barcellos
10.6084/m9.figshare.5176885.v1
https://cbbiomet.figshare.com/articles/journal_contribution/Potential_risk_of_thermal_stress_for_Bradford_bulls_in_Brazilian_tropical_and_subtropical_regions/5176885
<p>Thermal stress imparts physical and economical losses to
livestock production in temperate, subtropical and tropical regions of the
world. The Temperature and Humidity Index (THI) was brought as an option to
evaluate the morphological changes from bull semen according to environmental
stress. The objective of this work was to evaluate the reproductive performance
in Braford bulls, through the seminal quality, using THI as an environmental
stress in the tropical and subtropical regions in Brazilian. We used Braford
bulls from 5 different experiments, three farms located at the subtropical
Brazilian region and two at the tropical. Semen collections were performed at
least once a month through the experimental periods. Climate data was analysed
18 and 12 days prior to sampling corresponding to the spermiogenesis and the
epidydimal transit period. The data was analysed through ANOVA, means
differentiated through Tukey test and p-value was set at >0.05. The
subtropical and tropical region presented significant differences within the
area studied and specially when suggesting a climate zoning for animal
production. The percentage of days categorized as harmful was significant for
both regions and its correlated to the total and major sperm defects,
representing the importance of environmental changes as a stressor to sperm. Both
regions showed a significant variation between seasons that classified the
summer and the hot humid period as more stressful impact on the animal growth
and well-being. The Braford genetic, being a mixed of <i>Bos taurus indicus</i> and <i>Bos
taurus taurus</i>, would be a potential breed to be adapted to the tropics,
however a quantification of weather effect
is difficult to achieve accuracy on the acclimatization process, variance
between individuals, different farm management and changes in the combination
of environmental factors. </p>
2017-08-08 14:36:45
Braford bulls
temperature-humidity index
seminal defects
Environmental Management