Effects of thermal environment on dairy cattle under a grazing system in the Western Amazon, Brazil

Oliveira, Antonia Valcemira Domingos de; Reis, Eduardo Mitke Brandão; Ferraz, Patrícia Ferreira Ponciano; Barbari, Matteo; Santos, G.S.; Cruz, M.V.R.; Silva, G.F.; Silva, A.O.L.

doi:10.1590/1678-4162-12743

Cited by 2 publications

(1 citation statement)

References 14 publications

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“…In an experiment carried out in the municipality of Sena Madureira-Acre, from January to March 2020, it was observed that the THI values were ≥72, and a similar result was also evidenced in this study in Rio Branco (Acre), which indicated a minimum THI of 72 in January (45). According to Soares et al ( 46), the high rates of THI favor the stimulus of thermal stress and, consequently, influence the reduction of milk production, reproduction, and low animal welfare performance in dairy cows (15, 31).…”

Section: Discussionsupporting

confidence: 87%

Evaluation of the temperature and humidity index to support the implementation of a rearing system for ruminants in the Western Amazon

Silva,

Printes,

Lima

et al. 2023

Front. Vet. Sci.

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The good productive and reproductive performance of the animals depends on multiple factors, including favorable climatic conditions, which are responsible for causing changes in the physiological and behavioral responses. Thus, the objective of this study was to evaluate the temperature and humidity index (THI) to support the implementation of a rearing system in ruminants in the Western Amazon, Brazil. Monthly temperature and relative humidity data were obtained from the Database for Teaching and Research (BDMEP) for the capitals Manaus (Amazonas), Boa Vista (Roraima), and Rio Branco (Acre), considering a historical series of 27 years (1993 to 2020), referring from January to December. In the capital Boa Vista, the months of January, February, May, June, and July showed an indication of mild stress and the months of March, April, August, September, October, November, and December had moderate stress. In Rio Branco, all months of the year presented the average THI in mild stress with variations of lower THI (73) and higher THI (77). In the capital Manaus, the months from January to July signaled mild stress, but from August to November, there was moderate stress, and in December, there was mild stress. It is possible to observe significant climatic variations during the months as well as the years of study, with the animals under thermal stress with THI > 72 or in a warning signal, with a gradual increase in temperature and humidity indices over the last 10 years. The importance of the breeding system and the consideration of environmental factors, such as the THI, are fundamental for the wellbeing and performance of cattle raised in the field. Our results support the adoption of heat stress mitigation strategies for ruminants in Western Amazon.

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Section: Discussionsupporting

confidence: 87%

Evaluation of the temperature and humidity index to support the implementation of a rearing system for ruminants in the Western Amazon

Silva,

Printes,

Lima

et al. 2023

Front. Vet. Sci.

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Impact of Heat Stress on Oocyte Developmental Competence and Pre-Implantation Embryo Viability in Cattle

Gómez-Guzmán,

Parra-Bracamonte,

Velazquez

2024

Animals

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Rectal and vaginal temperatures are utilised in both in vivo and in vitro models to study the effects of heat stress on oocyte competence and embryo viability in cattle. However, uterine temperature increases by only 0.5 °C in heat-stressed cows, significantly lower than simulated increases in in vitro models. Temperature variations within oviducts and ovarian follicles during heat stress are poorly understood or unavailable, and evidence is lacking that oocytes and pre-implantation embryos experience mild (40 °C) or severe (41 °C) heat stress inside the ovarian follicle and the oviduct and uterus, respectively. Gathering detailed temperature data from the reproductive tract and follicles is crucial to accurately assess oocyte competence and embryo viability under realistic heat stress conditions. Potential harm from heat stress on oocytes and embryos may result from reduced nutrient availability (e.g., diminished blood flow to the reproductive tract) or other unidentified mechanisms affecting tissue function rather than direct thermal effects. Refining in vivo stress models in cattle is essential to accurately identify animals truly experiencing heat stress, rather than assuming heat stress exposure as done in most studies. This will improve model reliability and aid in the selection of heat-tolerant animals.

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Effects of thermal environment on dairy cattle under a grazing system in the Western Amazon, Brazil

Cited by 2 publications

References 14 publications

Evaluation of the temperature and humidity index to support the implementation of a rearing system for ruminants in the Western Amazon

Evaluation of the temperature and humidity index to support the implementation of a rearing system for ruminants in the Western Amazon

Impact of Heat Stress on Oocyte Developmental Competence and Pre-Implantation Embryo Viability in Cattle

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