Elsevier

Journal of Thermal Biology

Volume 81, April 2019, Pages 128-136
Journal of Thermal Biology

The dynamic adaptation of Brazilian Brahman bulls

https://doi.org/10.1016/j.jtherbio.2019.02.016Get rights and content

Highlights

  • The dynamic adaptation of beef cattle was evaluated in this study.

  • The techniques of multivariate analysis were fundamental to reach the objective of the investigation.

  • Brazilian Brahman steers exhibited physiological and morphological traits that promote dynamic adaptation according to season in savanna biome conditions.

Abstract

Heat stress is one of the most important factors that affect the performance of some Bos taurus breeds and crosses in tropical regions. The Brahman breed was developed in hot regions of the world and often has genes that confer resistance to heat stress compared to other breeds of beef cattle. The goal of this work was to evaluate the adaptive responses of Brahman bulls, based on physiological, hormonal and hair characteristics according to season. The physiological, hormonal and hair characteristics were rectal temperature (RT), respiratory rate (RR), sweating rate (SR), triiodothyronine (T3), thyroxine (T4), cortisol concentrations (CO), coat thickness (CT), hair length (HL), hair diameter (HD) and hair density (ND). These were recorded in Brahman bulls from a Cerrado biome during four seasons: spring (21 September to 20 December), summer (21 December to 17 March), autumn (18 March to 20 June) and winter (21 June to 20 September). Data was analyzed using a general linear model that included season as a fixed effect; in addition, multivariate tests and logistic regression were also used to characterize the animals within each season. The meteorological variables defined the four seasons, besides identifying climatic differences between them. Significant differences (P > 0.05) were found for most of the physiological, hormonal and hair characteristics according to season. The Brahman bulls presented particular adaptive characteristics in each season. Individually, most of the Brahman bulls presented the same adaptive reaction in each season; particular similarity occurred for the summer and autumn. This pattern is a reflection of the inter-relationships between physiological responses and hair characteristics.

Introduction

Environmental high temperatures are detrimental to the productivity of the livestock industry because animals of genotypic desired characteristics for beef production normally have higher endogenous heat due to their metabolic activity. Heat stress (HS) is one of the most important factors that affect the performance of some Bos taurus breeds and their crosses in tropical regions, especially when they are managed in extensive conditions (Silanikove, 2000, McManus et al., 2011). In Brazil, the search for heat tolerant genotypes has increased over the years because of their ability to adjust to climatic changes (Urbano et al., 2015). The Bos indicus cattle are particularly adapted to hot climates and possess superior ability to regulate body temperature (Hansen, 2004). According to Dikmen et al. (2018), the Brahman breed were developed in hot regions of the world and often have genes that confer resistance to HS, compared to Angus and Hereford breeds of beef cattle.

Individual susceptibility to HS is influenced by many factors, including its species, fat score, skin and coat color, temperament, sex, and skin thickness (Scholtz et al., 2013). The capacity of the animals to maintain equilibrium with the thermal environment is directly associated with their ability to trigger thermoregulatory mechanisms. This depends on a pool of morphological, physiological and hormonal traits acquired during the evolutionary process, in order to guarantee the efficiency of thermoregulation (Façanha et al., 2016).

Brahman cattle have strong skin pigmentation which filters the intense shortwave radiation as well as keeping the breed free of cancer. A special feature of the Brahman breed is their ability over other breeds to sweat freely, which contributes greatly to their heat tolerance, as found in the research by Silva et al. (2017). Other adaptive advantages that make the Brahman well suited to many environmental conditions include the ability to consume lower-quality food, to walk longer distances for feed and water, to be resistant to internal and external parasites and the ability to reproduce on a regular basis in a stressful environment (Hoffmann, 2010, Mu et al., 2013). A factor which contributes to the Brahman's unique ability to withstand extreme temperature is a short, thick, glossy coat, which reflects much of the sun rays, allowing them to graze in midday sun without suffering.

The goal of this work was to evaluate the adaptive responses of Brahman bulls, based on physiological, hormonal and hair characteristics according to season. The hypothesis is that there is a specific adaptive trait profile for each season.

Section snippets

Material and methods

The study was performed in a commercial farm located in Uberlândia city in Minas Gerais state, Brazil, at 18°55′S, in the Cerrado biome. Sixty-three Brahman bulls were used, whose initial age ranged from 233 to 264 days and initial body weight (BW) was 193.5 ± 54 kg.

The physiological, hormonal and coat variables were collected from spring to winter, marked by the following dates: spring (21 September to 20 December), summer (21 December to 17 March), autumn (18 March to 20 June) and winter (21

Results

Air temperature (AT) presented variation close to 5.4 °C between seasons, ranging from 22.8 ± 2.7 °C to 28.2 ± 2.5 °C in the winter and summer seasons with significant difference (P < 0.05), respectively (Fig. 1). In addition, minimum and maximum relative humidities (RU) were observed between 44.0 ± 2.1% (spring) and 71.2 ± 5.6% (autumn) with significant difference between seasons (P < 0.05). In these circumstances, minimum and maximum wind speed (WS) ranged from 0.4 ± 0.8 m s-2 (autumn) to

Discussion

The present investigation is the first to describe the adaptive responses of Brahman bulls, based on physiological, hormonal and hair characteristics according to season using a multivariate approach, specifically canonical analysis. Empirically, it is expected that some periods of the year will be more stressful for animals; however, phenotypic plasticity allows them to overcome these moments. The associated effects of high AT, RU and solar radiation can result in a more stressful environment,

Conclusion

We concluded that Brazilian Brahman bulls exhibited physiological responses, hormonal and morphological characteristics that promote dynamic adaptation according to season in Cerrado biome conditions.

For that reason, this breed can be indicated for meat production in an extensive system. However, special attention must be paid to heat stress management during the hottest and humid months, in this case January to June, corresponding to the summer and autumn seasons.

Multivariate analysis was

Authorship statement

The idea for this paper was conceived by D. Façanha and J. Ferreira. The experiments were designed by J. Ferreira. The experiments were conducted by D. Façanha, J. Leite, W. Costa and A. Vasconcelos. The data were analyzed by J. Ferreira, R. Silveira, J. de Sousa and L. Asensio. The paper was written by D. Façanha and J. Ferreira.

Acknowledgement

The authors acknowledge the Uberbrahman Group, specially Dr Thiago Camargo and Dr Aldo Valente, that supported the present study.

Dra Débora Andréa Evangelista Façanha is an associate professor at Department of Animal Science – Federal University of Semiarid (UFERSA), Brazil. Her research program is focused in thermotolerance and physiologic adaptation to semiarid environment. Her interests include molecular markers, omic tools and improvement of locally adapted breeds, especially in ruminants.

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    Dra Débora Andréa Evangelista Façanha is an associate professor at Department of Animal Science – Federal University of Semiarid (UFERSA), Brazil. Her research program is focused in thermotolerance and physiologic adaptation to semiarid environment. Her interests include molecular markers, omic tools and improvement of locally adapted breeds, especially in ruminants.

    Josiel Borges Ferreira is Ph.D. candidate in the Graduate Program of Animal Science at Federal University of Semiarid (UFERSA), Mossoró, Rio Grande do Norte, currently conducts research in the area of animal conservation, genetic improvement and innovative methods for statistical analysis and is an editorial member of Journal of Veterinary Science and Research.

    Dra Jacinara Hody Gurgel Morais Leite is Ph.D. in the Graduate Program of Animal Science PPGCA) at Federal University of Semiarid (UFERSA) and post-doc position in the PPGCA, Brazil. She has extensive experience in studios with assessment of adaptive capacity in animals managed in a tropical region.

    Dr José Ernandes Rufino de Souza received his undergraduate degree in agronomy engineering from the Federal University of Ceará (UFC). He received his doctorate in Animal Science from Federal University of Minas Gerais (UFMG), currently professor genetic improvement in Federal University of Semiarid (UFERSA), Mossoró, Rio Grande do Norte. His interests include the animal conservation and genetic improvement of locally adapted breeds.

    Dra Magda Maria Guilhermino is a received her doctorate in University of Reading in England, UK. Currently is an titular professor at Federal University of Rio Grande do Norte (UFRN), Brazil. Her interests include sustainable production systems, agricultural familiar systems and polices for agriculture development.

    Dr Wirton Peixoto Costa received his a DVM from the Federal University of Semiarid with a doctorate in Federal University of Paraíba (UPB), Brazil. Currently is an professor at UFERSA and his interests include adaptability, veterinary anatomy and diagnostic imaging. He is currently president of the Council of Veterinary Medicine of the State of Rio Grande do Norte.

    Dr Luis Alberto Bermejo Asensio is professor of University of La Laguna (Spain) in the Department of Agrarian Economy, Sociology and Policy and his research and teaching are focused on rural development, land planning, grazing management and management of breeding programs of local breeds in the context of farmer organizations.

    Dra Angela Maria de Vasconcelos is a received her doctorate in Animal Science from Federal University of Viçosa (UFV), currently professor in University of Vale Acaraú (UVA), Sobral, Ceará. Her interests include animal production and nutrition, adaptability and livestock.

    Robson Mateus Freitas Silveira is a Master candidate in the Graduate Program of Animal Science at University of Vale Acaraú (UVA), Sobral, Ceará, currently conducts research in the area of animal nutrition and livestock science.

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