Abstract Heat stress induces failures in the physiological mechanisms that regulate the body temperature of farm animals and causes a loss in their productive and reproductive potential. Thus, we performed a scoping review to systematically map, describe, and classify primary research that assessed the effect of heat stress on the reproductive, physiological, and productive parameters of livestock. Electronic databases were searched to retrieve full text, peer-reviewed experimental or cohort studies published from 1980 to August 2018. We included in vivo and in vitro studies exposing animals or cells to heat stress conditions and used a control group. Studies were evaluated based on title and abstract and then selected for final inclusion based on full text. We performed data charting to describe and visualize the evidence. In total, we included 466 studies, among which bovines and pigs were the most frequent species studied. Reproductive and physiological parameters were the main groups of outcomes assessed, and studies using adult females predominated. Seventy percent of the studies were experimental, and almost half of the studies used natural environmental conditions to assess the effect of heat stress in animals. Most of the studies were performed in the Americas and Asia, and three journals provided one-third of the publications. The systematic evidence synthesis presented herein outlines the trends of research performed to assess the effect of heat stress on livestock and allowed us to define future secondary studies to extend our knowledge about the negative impact of heat stress on the productivity of farm animals.

O objetivo deste trabalho foi estudar a conduta reprodutiva de duas cepas de R. (B.) microplus, uma coletada no campo (Nativa) e outra de referência (Média Jóia), por dois anos, calculando o índice de eficiência reprodutiva (REI) e o índice de aptidão reprodutiva (RAI). Foram coletados mensalmente carrapatos fêmeas engurgitadas de cada cepa no período de Fevereiro de 2002 a Fevereiro de 2004. Estas foram pesadas e conservadas no laboratório até ovipositar. As massas de ovos foram pesadas individualmente e incubadas até a eclosão das larvas. O REI e o RAI foram calculados para cada coleta, agrupando os carrapatos em classe de peso de 100 mg. Os dados foram submetidos a uma análise de variância e prova de classe múltipla de Duncan (P < 0,05). Foram calculados os coeficientes de correlação de Pearson (P < 0,01) para estimar a associação entre o peso dos carrapatos engurgitados e o peso e número de ovos postos e eclosionados. A cepa Nativa mostrou um peso ao engurgitamento mais alto do que a cepa Média Jóia. Os valores de REI e de RAI em ambas cepas foram similares em todos as classes de peso, mostrando tendência cuadrática na Média Jóia e linear-cuadrática na cepa Nativa (P < 0,05). Ambos os índices por classe de peso no engurgitamento foram sempre mais altos na cepa Nativa (P < 0,05). Os valores de REI e de RAI de ambas cepas ao longo do estudo mostraram diferenças (P < 0,01), sendo a cepa Nativa a de melhor desempenho em ambos índices, incluindo um melhor desenvolvimento durante a estação seca. Observou-se uma correlação altamente significativa em todos os parâmetros, sobressaindo o número de ovos postos com o número de ovos eclodidos, 0,94 e 0,91, para a cepa Média Jóia e a Nativa, respectivamente.

The objective of this work was to study the reproductive behavior of two strains of R. (B.) microplus, one wild-caught (Native) and one reference strain (Media Joya) for two years, measuring the reproductive efficiency index (REI) and reproductive aptitude index (RAI). Engorged ticks from each strain were collected monthly from February 2002 to February 2004. These were weighed and kept in the laboratory until egg-laying. Oogenic masses were individually weighed and incubated until larvae emergence. REI and RAI were calculated from each sample, grouping ticks by weight in 100 mg range classes. An analysis of variance and Duncan's multiple rank tests were carried out on the data (P < 0.05). Pearson's correlation coefficients were estimated (P < 0.01) in order to determine the relationship between engorgement weight and the weight and number of laid and hatched eggs. The Native strain showed a higher engorgement weight than Media Joya strain. In both strains REI and RAI were similar in all weight classes; with a quadratic tendency in Media Joya and linear-quadratic in the Native strain (P < 0.05). Significant differences where observed when REI and RAI of both strains were compared along the duration of the study (P < 0.01) with the Native strain performing better in both indexes, including better performance during the dry season. All parameters studied showed highly significant correlation; eggs laid and eggs hatched were notably highly correlated, 0.94 and 0.91, for Media Joya strain and Native strain respectively.